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Chemotherapy in dogs and cats: indications, medications and side effects

Chemotherapy as a method of treating a cancer of a dog or a cat, we associate it with suffering.

Chemotherapy for dogs and cats

When we hear the word "chemotherapy ", We almost automatically imagine the sight of hospital beds, exhausted people with dark circles under their eyes, hiding hairless heads under scarves or caps, attached to infusion pumps, pulse oximeters and cardiac monitors.

This vision gives us an overwhelming feeling of sadness and hopelessness. No wonder that until the real necessity of chemotherapy appears in our immediate surroundings, we do not want to know anything about it and we avoid discussing this extremely difficult topic.

However, it happens - quite often, contrary to appearances - that chemotherapy breaks into our orderly life in a completely unexpected way - as a treatment option for our four-legged friend.

We learn that our dog or cat suffers from a malignant tumor, and one of the treatment options is precisely chemotherapy.

At first we are devastated by the diagnosis itself and instinctively defend ourselves against talking about administering chemistry, associating it as a necessary evil.

After a while, however, the first emotions subside, the shock passes, and a lot of questions are swirling in your head, such as, for example:

  • “How can I help my pet? "
  • "What are the treatment options for my dog ​​/ cat with cancer? "
  • “Can only chemotherapy really help?? "
  • "Are there no other - less drastic - treatments?? ".

Yes, in many cases surgery is the treatment of choice.

However, there is a fairly large group of neoplastic diseases for which surgery is not recommended because - for anatomical or functional reasons - it is simply impossible to perform. Therefore, in the case of such malignant diseases as, for example, lymphoma, leukemia, myeloma or tumors of the genital organs (venereal tumors), the only chance to stop or even cure the neoplastic process is chemotherapy or radiotherapy.

Chemotherapy is also used as adjunctive therapy after surgery, or before and after surgery to remove highly metastatic tumors (such as osteosarcoma, angiosarcoma, milk strips adenocarcinoma).

Sometimes, unfortunately, the only alternative is to euthanize the animal in order to reduce its suffering from cancer.

Because the subject of chemotherapy in an animal triggers a huge variety of emotions in their caregivers, which are usually difficult for them to deal with, it often happens that there is little time for a substantive conversation with the doctor, or many key information is lost to the owners due to strong agitation.

They also often forget to ask about matters that may play a significant role in making decisions about how to deal with a sick pet, or they simply do not know what to ask about.

Of course, the veterinarian will explain all these essential issues in an understandable manner and make sure that owners are aware of both the diagnosis and prognosis and further treatment options, and provide this information in writing. However, I know from experience that sooner or later doubts arise and a lot of questions arise that have not been asked before, and each new piece of information raises new questions

This study is about chemotherapy in dogs and cats.

Presenting this issue in the form of questions and answers is a deliberate procedure aimed at finding interesting content quickly.

If you are a carer of an animal that is receiving or will receive chemotherapy, I invite you to read this article. I believe that it will help you get through this time, which - contrary to appearances - does not have to be difficult and depressing at all. But more on that later.

  • What is chemotherapy?
  • What are the types of chemotherapy used in dogs and cats?
  • How chemotherapy works?
    • The cell cycle
  • When we use chemotherapy to treat dogs and cats?
  • How chemotherapy affects the dog / cat's chances of survival?
  • How can I determine what is best for my dog ​​/ cat?
  • Are there studies qualifying for the administration of chemotherapy in the dog / cat??
  • How is chemistry administered?
  • How is chemotherapy administered in a dog / cat?
  • What drugs are used for chemotherapy in dogs and cats?
    • Alkylating drugs
    • Antimetabolic drugs
    • Anticancer antibiotics
    • Plant alkaloids (rosacea alkaloids)
    • Platinum derivatives
    • Other anti-cancer drugs
  • Are there any studies on anti-cancer drugs?
  • What is monotherapy and combination chemotherapy?
  • What are chemotherapy protocols / regimens?
  • Will the chemotherapy make my dog ​​/ cat feel unwell??
  • What are the common side effects of chemotherapy?
    • Urinary tract disorders (kidneys, bladder)
    • Heart muscle damage
    • Chemotherapy neurotoxicity
    • Hepatotoxicity
    • Anaphylactic reaction
    • Lethargy
    • Increased hunger / thirst / urination
  • How to prevent side effects from chemotherapy?
    • Prevention of nausea and vomiting
    • Prevention of infection
    • Prevention of thrombocytopenia
    • Prevention of extravasation of the cytostatics
    • Prevention of nephrotoxicity during chemotherapy
    • Prevention of hemorrhagic cystitis
    • Prevention of cardiotoxicity
    • Prevention of hepatotoxicity
    • To prevent an anaphylactic reaction
  • How to treat the side effects of chemotherapy?
    • Management of loss of appetite
    • Management of weight loss
    • Treatment of nausea and vomiting
    • Treatment of gastrointestinal motility disorders
    • Management of neutropenia
    • Management of thrombocytopenia
    • Management of cytostatics extravasation
    • Treatment of hemorrhagic aseptic cystitis
    • Management of an anaphylactic reaction
  • What should I do if I notice something very disturbing?
  • How long will my pet receive chemotherapy?
  • Is it safe for me to stay around my pet while on chemotherapy?
  • What precautions should be taken when administering oral chemotherapy drugs to the dog / cat?
  • How to handle chemotherapy drugs at home?
  • How can I support my pet during chemotherapy?
  • What happens after chemo treatment ends?
  • How much does chemotherapy cost for a dog / cat?
  • How my pet responds to chemotherapy?

What is chemotherapy?

What is chemotherapy?

The most general definition of chemotherapy is simply to treat ailments with chemotherapy. In this sense, we use chemotherapy every day:

  • antibiotics,
  • non-steroidal anti-inflammatory drugs,
  • painkillers,
  • vitamins,
  • dietary supplements.

They are mostly synthetic compounds, produced in laboratories as a result of various chemical reactions.

However, we are interested in the oncological definition - chemotherapy in a specific treatment of cancer involves the administration of drugs to the animal or human body (or a specific place in the body) with strong cytotoxic properties (i.e. destroying cells, mainly cancerous), with the assumption of causing as little damage as possible to normal, healthy cells.

The goal of chemotherapy is to achieve complete or partial remission, i.e. regression of lesions and maintain it for as long as possible without exposing the animal to additional suffering. Put simply - Chemotherapy is a therapy that helps to eliminate or slow down the growth of the cancer.

Chemotherapy was developed in the 1940s. In the 1980s, scientists learned about the effects of mustard gas, used in chemical warfare.

It has been found that people exposed to the gas have a very low white blood cell count.

Researchers have argued that if a substance has an effect on rapidly growing leukocytes, it may also affect rapidly growing cells in some blood cancers. This led to further research and development of various drug protocols.

Many different groups of chemotherapeutic drugs are used in the treatment of cancer in veterinary oncology. The use of a particular drug or combination of drugs depends on many factors, including the type of cancer being treated and the overall health of the animal.

Once chemotherapy treatment is started, protocols can be modified to ensure the most effective treatment with the fewest side effects. Therefore, each chemotherapeutic regimen is closely tailored to the specific needs of a particular patient.

What are the types of chemotherapy used in dogs and cats?

Types of chemotherapy used in dogs and cats

Chemotherapy covers a wide range of therapeutic procedures.

Terms such as "adjuvant", "neoadjuvant", "consolidation" and "palliative" often cause anxiety and consternation in caregivers of animals to be treated; if these concepts are not properly defined and explained, they may even be the reason for giving up chemotherapy because it is considered too complicated and involving a method of treatment.

However, these terms are only apparently confusing.

  • Adjuvant chemotherapy it's just adjuvant chemotherapy. It is used to destroy microscopic debris of cells that may be present after surgical removal of the tumor. Its purpose is to destroy possible micrometastases and reduce the risk of recurrence of the neoplastic disease. So it is, in a way, an enhancement of another type of treatment.
  • Neoadjuvant chemotherapy it is given before surgery to remove the tumor. It is used before surgery to reduce the size of a large tumor. This reduction in the mass and size of the neoplastic lesion makes it possible to perform a radical, but definitely less extensive surgery.
  • Combination chemotherapy is chemotherapy that uses many drugs according to a specific administration schedule.
    These drugs differ in their mechanisms of action and toxicity.
  • Induction chemotherapy is chemotherapy given to induce remission.
  • Consolidation chemotherapy is chemotherapy given after remission has been achieved. The purpose of its administration is to maintain remission. Intensifying chemotherapy is also given to maintain remission, but is given a different medication than the medication used to maintain remission.
  • Maintenance chemotherapy - chemotherapy given in lower doses to prolong remission. It is only used for certain types of cancer, mainly acute leukemia. Terms such as induction, consolidation, intensification and maintenance are mainly used in the treatment of acute human leukemia.
  • First-line chemotherapy - chemotherapy, which, thanks to research and clinical trials, has been recognized as the most effective in the treatment of a given type of cancer. You can name her standard chemotherapy.
  • Second-line chemotherapy - chemotherapy given when the disease has not responded to treatment or has come back after first-line chemotherapy. In some situations it is called emergency chemotherapy.
  • Palliative chemotherapy is a type of chemotherapy that is given specifically to combat symptoms, with no hope of significantly shrinking the tumor. It cannot cure the disease, it only reduces the clinical symptoms associated with cancer and prolongs survival. This chemotherapy is significantly less toxic. In the vast majority of cases in veterinary medicine, chemotherapy is of a palliative nature.
  • Metronomic chemotherapy - is the administration of a cytostatic drug in very low doses, usually daily or every other day by mouth. It can be used in cases of inoperable tumors, such as soft tissue sarcomas, angiosarcomas, osteosarcomas, carcinomas and melanomas. It is also a palliative alternative to standard chemotherapy. Currently, it is most often a type of adjuvant chemotherapy after tumor removal, its incomplete resection or with radiotherapy and standard chemotherapy. Since the doses of cytostatics are even lower than with conventional therapy, the risk of side effects is minimal, and when they do occur, they are usually mild. An additional advantage is that the animal does not need to be hospitalized, because the owner administers the medicines himself at home. This results in a low cost for the treatment and monitoring of the animal. The most important disadvantage of metronomic therapy is that the chance of achieving complete remission with this method of treatment is really small.
  • Electrochemotherapy. It is used for tumors that occur on the surface of the skin or under the skin, and is especially used for squamous cell carcinoma, melanoma, sarcoma, mast cell tumor, adenocarcinoma, lymphoma and sarcoids. The mechanism of its operation uses the phenomenon of reversible destabilization of cell membranes under the influence of external electric field pulses of appropriate intensity. The neoplastic lesion is injected with a chemotherapeutic agent (most often bleomycin or cisplatin), and after about a minute the tumor is exposed to electricity using contact or puncture electrodes. Thanks to this, the molecules of the chemotherapeutic agent can cross the cell membrane barrier and penetrate inside the cancer cell, destroying it. The entire procedure is performed under general anesthesia.

How chemotherapy works?

How chemotherapy works?

Under normal conditions, cells live, grow, and die predictably.

Cancer occurs when certain cells in the body get out of control, divide, and make more cells without being able to stop the process.

To remove cancerous lesions and prevent them from spreading, chemotherapy is introduced to attack these rapidly dividing and growing cells. However, cells are attacked by cytotoxic drugs whether they are cancerous or not.

Chemotherapy drugs target all cells that grow and divide.

Individual drugs can work by many different mechanisms, such as damaging the cell's genetic material (DNA) or preventing the cell from dividing.

However, cytotoxic drugs cannot distinguish between malignant cancer cells and normal ones. This means that all rapidly dividing cells are potentially sensitive to chemotherapy.

This toxic effect on healthy, rapidly growing, or self-renewing cells and tissues in the body is the cause of most of the side effects seen with chemotherapy.

Fortunately, normal tissue continues to grow and repair itself, so damage from chemotherapy is rarely permanent.

The cell cycle

Cells that divide, both healthy and cancerous, undergo an orderly process of division known as the cell cycle.

It is important from an oncological point of view as it helps to plan and administer chemotherapy.

Cell growth takes place in several phases:

  • The mitosis (M) phase is the beginning of the cell cycle. This is when the chromosomes attach to the mitotic spindle and the cell divides into two daughter cells. The M phase lasts 30 to 90 minutes.
  • The G1 phase (with. Gap (break) has a variable duration and may be hours or days. In this phase, the synthesis of proteins and RNA takes place.
  • The S-synthesis phase lasts 6 to 8 hours during which DNA is synthesized.
  • The G2 phase is the second period of RNA and protein synthesis lasting 2 hours.
  • The last phase of G0 is the resting period in which cells are inactive. They can stay in this phase for a long time.

The goal of chemotherapeutic drugs is to kill cancer cells, but with the simultaneous administration of a dose of cytostatics that will cause "tolerated " damage to normal body tissues.

A clear feature of cancer cells is that they grow faster than most healthy cells.

Therefore, chemotherapy drugs usually affect the replication process of these rapidly dividing cells by interfering with DNA or RNA synthesis at the cellular level. The drug binds to DNA and changes the replication process, cellular activity is thus stopped and the cell dies.

There is a balance between destroying as many malignant cells as possible and leaving enough healthy cells to regenerate.

A cytotoxic drug can act in one or more phases of cell division (depending on the type of medication), for example:

  • Alkylating drugs, cytostatic antibiotics and platinum derivatives disrupt DNA replication (i.e. they work in the S phase of the cell cycle).
  • Antimetabolic drugs, in turn, disrupt the synthesis of purine and pyrimidine bases (G1 and G2 phases).
  • Vinca alkaloids interrupt mitosis (i.e. act in the M phase).

Anticancer drugs can be classified into three categories according to their cellular effects.

  1. Non-cell cycle specific drugs act on cells whether they divide or not.
  2. In contrast, cell cycle-specific drugs kill cells at all stages of the cycle.
  3. Finally, the most specific factors are cell cycle phase-specific drugs - they kill cells that are only found in one (specific) phase of the cycle.

Thus, cells that divide rapidly are the most susceptible to the effects of anti-cancer drugs.

Therefore, rapidly growing tumors are the most sensitive to chemotherapy, while slow-growing tumors are poor candidates for this type of treatment.

Cells in the G0 phase are not damaged by most drugs and remain viable during chemotherapy. After its completion, they can re-enter the cell cycle to proliferate.

Small tumors have a higher percentage of dividing cells and have a short double-volume time. As tumors grow, the percentage of dividing cells decreases, the time to double in volume increases, and spontaneous cell death occurs.

Increased tumor growth after relieving surgery (cytoreductive surgery to remove as much of the tumor as possible) should be used in treatment, because at this stage the tumor is theoretically most sensitive to chemotherapy.

When we use chemotherapy to treat dogs and cats?

Indications for anti-cancer therapy

Chemotherapy may be used as the sole treatment for certain cancers or may be used in conjunction with other therapeutic modalities such as surgery and radiation therapy, immunotherapy, complementary therapies, or a combination of therapies.

In dogs and cats, chemotherapy is usually recommended in the following situations:

  1. The animal was diagnosed with a malignant tumor and removed.
    • Chemotherapy is often prescribed after the surgical removal of a malignant tumor. In such cases, its aim is not only to prevent or delay the recurrence of the cancer at its original site, but also to prevent or delay the spread of the cancer. Examples of tumors where chemotherapy is routinely used include:
      • mast cell tumors,
      • spleen tumors,
      • malignant bone tumors.
  2. The animal has been diagnosed with a malignant tumor that is either inoperable (cannot be surgically removed) or has not been completely removed. Surgery has always been the method of choice for most solid tumors in domestic animals. However - although many cancers can be treated this way - it is not uncommon for surgery to be merely a palliative measure. When the tumor is considered inoperable or the surgical excision is incomplete, radiation therapy can be used.
    • Chemotherapy can be used after surgery or radiation therapy to eliminate certain types of microscopic cells that cannot be removed or are not completely removed during surgery. The administration of chemicals in these situations is intended to stop the growth of cancer cells elsewhere in the body and prevent metastasis.
    • Occasionally, chemotherapy can be used alone to treat tumors that are not amenable to surgical removal or radiotherapy, or that have already metastasized. In most of these cases, the goal of treatment is not to cure the cancer but to improve the patient's quality of life.
    • In some cases, chemotherapy can be used to shrink large tumors before surgery.
    • Chemotherapy may also increase the effectiveness of other methods of destroying cancer. In some animals, radiation therapy may also be used to treat cancer during chemotherapy. Some chemotherapy drugs are effective in these situations because they increase the ability of radiation to kill cancer cells.
  3. The animal has multifocal disease - the tumors are present in more than one location.
    • Many cancers are not limited to one location, but are systemic diseases. All leukemias, most lymphosarcomas, and most myelomas are systemic diseases, and chemotherapy is the most effective treatment for these diseases. It gives the greatest chance of remission while maintaining a good quality of life.
  4. The animal has metastatic disease: the tumor has spread to other areas of the body.
    • There are also cancers with micrometastases already at diagnosis. Osteosarcoma, sarcoma hemangioma, mammary cancer, and oral melanoma have a very high incidence of undetected metastasis at diagnosis. These tumors can be treated with multicomponent therapy using surgery, chemotherapy, radiotherapy, and / or immunotherapy.

How chemotherapy affects the dog / cat's chances of survival?

Many factors influence the chance of survival. They include:

  • the type and stage of the tumor,
  • selected chemotherapy protocol and additional treatment regimen,
  • other important components, such as:
    • overall health,
    • age,
    • accompanying diseases and much more.

The animal has the best chance of survival if the disease is detected at an early stage. Early diagnosis can help heal, regenerate and prolong your dog or cat's life in comfort.

Unfortunately, malignant tumors are often incurable in animals.

In such cases, chemotherapy is still recommended as a way to relieve the clinical symptoms of cancer.

How can I determine what is best for my dog ​​/ cat?

Cancer diagnosis and the prospect of chemotherapy can be overwhelming and raise questions for good reason.

Most caregivers have serious doubts as to whether their pet will consent to chemotherapy or whether to undertake palliative treatment.

Still others consider euthanasia of the pet in such situations.

This is a very difficult situation as the pressure of having to make a quick decision causes additional stress and makes many owners go blank.

To get answers to your questions and understand the essence of further actions, try to systematize everything:

  1. First of all, make sure you get the final diagnosis. It will be preceded by a number of tests (imaging tests, biopsy, sometimes magnetic resonance imaging).
  2. Get the information you need. Your veterinarian will be sure to tell you everything you need to know, including statistics on prognosis, length of animal survival, treatment options, etc. Don't hesitate to ask questions if something is unclear to you or you need more data.
  3. Find out what your dog's or cat's quality of life will be - whether your pet has other health problems, such as heart or kidney disease? Ask about these and other factors that may affect the patient's comfort of life.
  4. Learn from others going through the same.
    Find online support groups for owners of dogs and cats with cancer. If there are none, try to create it yourself. It is an invaluable help for people who are going through the hell of cancer and chemotherapy (whether it concerns humans or animals).

Chemotherapy questions to help you decide what to do next:

What to ask your vet before chemotherapy?

  1. What is the life expectancy without treatment?
  2. What is life expectancy with treatment?
  3. What chemotherapy drugs will my dog ​​/ cat receive?
  4. How are they served?
  5. What is the administration of a chemotherapeutic drug like??
  6. How efficacy is assessed with different chemotherapeutic protocols?
  7. How often treatment will be given?
  8. How long will my pet receive treatment?
  9. What is the estimated cost of treatment?
  10. What side effects might my dog ​​/ cat experience?
  11. What clinical symptoms should I be concerned about?
  12. What symptoms require me to immediately see a doctor with the animal?
  13. Who should I contact after office hours if my dog ​​has symptoms that concern me?

What should you ask yourself?

  • Is the treatment for me or my pet worse than the cancer for any reason? Will the pet cooperate when it is necessary to take medications orally, draw blood, put on a cannula, etc.?
  • How my dog ​​/ cat handles trips to the vet? Will the stress related to visits not be too much of a burden for him??
  • What condition is my pet in?? Does he have any health problems apart from cancer?? Does he have any chronic disease?
  • Do I have any emotional, financial, and / or time blockages that will limit my ability to fully commit to treating my pet??
  • Are there any objective factors that may influence the decision to start treatment with chemotherapy (e.g. a small child at home, a nursing or pregnant woman)?

Making the decision to start chemotherapy treatment can be really difficult.

This process is heavily influenced by medical information, practical matters (such as the need for multiple visits, your pet's temperament, etc.) and the financial capacity of the pet's guardian.

Confront your concerns and thoughts with a veterinary oncologist. Doing so will allow you to make an informed and responsible decision.

Chemotherapy is not a standard treatment introduced to cure a given disease.

Unfortunately - in pets, oncological treatment is most often palliative.

Many owners struggle with their thoughts, associating the negative aspects of chemotherapy with human oncology. It is quite different with animals.

  • There is no long-term stay in the hospital, in isolation, away from loved ones, but rather regular visits to the oncology facility.
  • There are no numerous cables and drips, and there are single intravenous infusions or timed injections.
  • There is no baldness, but hair thinning is possible.
  • There is no persistent vomiting, nausea, loss of appetite or weight loss lasting months, but there is only a short-term deterioration in well-being and usually mild symptoms such as vomiting, diarrhea or lack of appetite, which usually disappear after 2-3 days.
  • There is no pain and suffering, and there is comfort in life.

Where do such differences come from? In veterinary medicine, the goals of cancer treatment are different.

There is no fight at all costs - in fact, at the beginning of the therapy, we make it clear that we are not fighting to cure the animal.

In the vast majority of cases, we cannot win over a malignant tumor in a dog or cat.

We are fighting for something completely different: for the quality of life.

That the time left to our ward should be painless time. So that the animal can enjoy life in good comfort for a while.

The added value of chemotherapy is extending the life of the dog or cat, which would have ended much faster without this type of treatment.

Unfortunately, not all animals react to chemistry as we would like them to.

Not all patients endure the poison in their veins without major perturbations.

Also, not everyone responds adequately to the drug


In many cases, we are unable to cure our veterinary cancer patients.

Therefore, our goal is to improve the quality of your pet's life. This is why chemotherapy is introduced - to minimize the discomfort caused by the cancer and - if it succeeds - to slow the progression of the disease.

Unfortunately, the statistics are inexorable. Complications occurring during the administration of chemotherapy will occur in 1/4 of patients, and in about 5% hospitalization will be necessary for this reason.

The consequences of this are clear, but not so obvious at the beginning: periodic deterioration of the patient's quality of life, extension or modification of the treatment protocol, financial burden on the owner, the need to commit and devote more time, etc.

All these factors may not be able to be borne by the caregiver and, as a result, the caregiver may choose not to continue treatment.

What are we fighting for?

As veterinarians, we are aware that we are fighting an unequal fight against cancer. We know that in most cases we are destined to fail.

For this reason, the basic question that guides us when choosing the treatment option for an animal with cancer is:

“What are the benefits for the patient if we introduce cancer treatment? "

Cancer patients benefit in three ways:

  1. The animal is cured. Aggressive therapy is usually required to cure patients with advanced cancer. It carries the risk of significant complications and side effects, and because in veterinary medicine we strive primarily to ensure the comfort of the animal and a good quality of life, cure usually (with some exceptions) cannot be obtained. So what remains is palliative treatment, which can be radiotherapy, chemotherapy, and even surgery. The aim of this procedure is to minimize the risk of complications related to the cancer and its treatment. Inevitably, this happens at the expense of the chances of curing the patient or extending his life.
  2. The tumor is not cured but the animal's life is extended with the same or better quality of life.
  3. The tumor cannot be cured, nor is it possible to extend the life of the animal, but the quality of life is better.

The veterinarian must objectively assess whether a patient would require chemotherapy or a more sensible and - most importantly - in the best interest of the animal - palliative treatment.

In such situations, the results obtained after the entire diagnostic process, including the stage of the disease and the degree of malignancy of the neoplasm, are extremely important:

  • Low-grade lesions grow slowly and rarely metastasize, and are treatable with extensive surgical resection.
  • High-grade tumors grow quickly and metastasize readily, and are rarely cured even with extensive surgical excision.

If the animal has low-grade tumors, no other disease, removable tumor and no metastasis, the patient undergoes aggressive surgery.

Cure may be obtained with complete excision.

If the tumor has not been completely resected, the procedure may be two-fold:

  • Regular inspection of the excision site and observation that the neoplastic process does not resume.
  • Radiotherapy.

High-grade tumors have a much worse prognosis.

The likelihood of a cure is much lower, even with aggressive multi-path therapy.

In such a situation, consideration should be given to whether aggressive therapy could significantly extend the life of the dog or cat compared to palliative care.

  • If aggressive treatment does show a significant advantage in extending the patient's life compared to palliative management, and the owner is confident that he or she wishes to receive such treatment, aggressive surgery, chemotherapy and / or radiation therapy should be considered.
  • If, on the other hand, aggressive cancer management does not substantially extend the patient's life, and adverse effects worsen his quality of life, the management should be palliative. Treatment of a disease should never be allowed to be more burdensome for an animal than the disease itself.

Are there studies qualifying for the administration of chemotherapy in the dog / cat??

Before starting the administration of chemotherapeutic drugs, it is necessary to determine several important parameters.

  • Determining the type of tumor. This information is important not only from a diagnostic point of view. The type of tumor predicts how it will respond to cytotoxic drugs. Histopathological examination of the examined tumor informs us about the nature of the changes, the degree of malignancy, metastatic potential and the susceptibility of neoplastic cells to the action of cytotoxic drugs. Not every cancer is chemically sensitive, so the use of drugs that put a heavy burden on the patient's body, suffering from chemoresistant tumors (e.g. sarcoma, cancer or melanoma) not only will not bring the expected results, but may also cause side effects. Neoplasms that respond fairly well to the action of chemotherapeutic agents are, for example,. hematopoietic malignancies (e.g. lymphomas) or venereal tumors.
    • Certain cancers, such as. Low-grade fibrosarcomas with low metastatic potential do not require administration of chemotherapeutic drugs.
      Their use in such cases may even worsen the prognosis.
    • Other neoplasms (e.g. melanomas) can be completely resistant to chemotherapy, so administration of cytotoxic drugs does not make sense.
  • The stage of the neoplastic disease (stage), the presence of possible paraneoplastic syndromes.
  • The clinical condition of the patient with particular emphasis on his condition and the capacity of internal organs, such as the liver, kidneys, pancreas, heart.
    • Before starting chemotherapy, blood chemistry tests are performed to assess the efficiency of internal organs, as well as to detect possible paraneoplastic syndromes.
    • A complete blood count is also performed. The hemogram will be a reference point for tests performed before each subsequent administration of chemotherapy in order to assess the degree of drug-induced myelosuppression (in other words: whether and to what extent the cytostatics suppressed the bone marrow function).
    • Imaging tests, such as chest X-rays or abdominal ultrasound, are used to detect possible metastases.
    • Electrocardiography and echocardiography are recommended when doxorubicin is included in the chemotherapeutic protocol.
    • All these tests are intended to determine whether there are objective contraindications for administering chemotherapy in a particular patient.
  • If the results of tests qualifying for administration of chemotherapy are satisfactory, it is possible to use chemotherapeutic drugs. The next step is to determine what drugs and in what regimens will be administered to the animal.

How is chemistry administered?

How is chemistry administered?

Chemotherapy can be used alone or in combination with other therapeutic interventions, such as radiation therapy or surgery, as a complement to them.

In animals, it is most often administered intravenously, orally, intraperitoneally or directly into the tumor.

  • The route of administration of a chemotherapeutic drug depends on the type of drug, the location of the tumor and the general condition of the patient.
  • Most cytostatics are administered by the intravenous route. However, some drugs may cause shock after intravenous administration, so they are recommended to be administered by the intramuscular route (e.g. asparaginase) or subcutaneously (cytosine arabinoside). These drugs cannot be used at home, but must be administered at a reference cancer facility.
  • Some drugs used in chemotherapy are oral preparations (dragées, tablets). They can be given at the clinic, but they can also be applied by the pet's caregiver at home.
  • For lesions in the spinal cord (lymphomas), drugs may be administered into the spinal canal.
  • In cats - due to the difficult intravenous access - it is possible to administer drugs intraperitoneally.

The method of administering a chemotherapeutic drug, the frequency of its administration, the number of drugs used, and the duration of chemotherapy in an animal depend on several factors, the most important of which are:

  • type of cancer,
  • the extent of the disease,
  • overall health of the animal.

The duration of chemotherapy depends on the type of cancer you have, the extent of the disease, and how the tumor responds to treatment. Treatment periods may vary from weeks to years.

The prospect of administering chemotherapy over the years may be daunting, but it should be viewed from the other hand - long treatment periods are not a cause for concern, on the contrary - it means the treatment is working.

Some animals require chemotherapy for the rest of their lives. For others, treatments may be phased in or discontinued after weeks or months, provided the tumor is in remission, i.e. there is no detectable evidence of its presence in the body.

If the cancer comes back, chemotherapy can be restarted.

In some cases, slow infusions or repeated treatments throughout the day may require your pet to spend the day in the hospital. Treatments are usually repeated weekly to every 3 weeks.

Antineoplastic drugs are given on the basis of the body surface area (unlike "regular" drugs, which are dosed according to body weight).

However, in dogs weighing less than 10 kg, the dose of some cytostatics may be converted based on body weight.

The specific dose of the drug for a patient also depends on general health and drug sensitivity. The dose must be high enough to be medically effective, but not so high as to cause unnecessary damage to healthy cells.

Most chemotherapy regimens begin intensive therapy with higher and more frequent doses of the drug to stop the disease.

The frequency of administration of chemotherapeutic agents is related to the time during which they exert the strongest toxic effects on tissues and organs, especially the bone marrow.

This is called. nadir and is observed with most drugs between 5 and 14 days after administration. Therefore, drugs are administered in a pulsed manner, which protects healthy cells (especially in the gastrointestinal tract) and allows them to regenerate.

The type of cancer, the extent of the disease, and the overall health of the animal help oncologists develop a treatment protocol that is appropriate for the individual patient.

The oncologist presents the owner with the planned chemotherapy regimen - it includes the type of drugs, their dose and the schedule of administration.

How is chemotherapy administered in a dog / cat?

The mere administration of chemotherapy to a dog or cat, contrary to appearances, is not particularly complicated, provided that everything has been properly planned and prepared.

Upon qualification for chemotherapy, the pet owner is usually given a chemotherapy drug regimen.

It shows the dates of the planned administrations along with the names and doses of cytostatics, and often also lists the tests expected to be carried out on a given day.

  1. There is a routine check-up at each visit. Before administering the dose of the chemotherapeutic agent, an interview with the owner is made regarding the animal's well-being and any symptoms that alarm the caregiver. You should report any changes, no matter how minor they may seem.
    It is important to provide your doctor with the following information:
    • general well-being of the dog / cat,
    • medications given,
    • any changes in eating / drinking / defecation habits,
    • any signs of illness,
    • behavioral changes,
    • tumor change (if visible).
  2. Then a physical examination is performed, the patient is weighed, an intravenous cannula is inserted, and blood is drawn for laboratory tests.
    • Complete blood counts should be performed before each administration of the cytostatics.
      A determination of the number of white and red blood cells and platelets is necessary to ensure that the treatment is safe and that the animal can be given another dose of chemotherapy. In some cases, your pet's treatment may be delayed for several days because of a low white blood cell count.
    • Since many drugs also affect healthy cells and organs, blood chemistry will also be checked prior to administration of chemotherapy. Abnormalities in any of the values ​​may require dose adjustment of the cytostatics or treatment delay.
    • Depending on the type of chemotherapy drugs and the clinical condition of your pet, other tests may also be ordered, such as:
      • urine analysis,
      • determination of a specific lipase (to exclude pancreatitis),
      • electrolyte tests, etc.
        However, these are not tests carried out at every visit.
    • Periodically, additional diagnostics may be needed, such as x-ray, ultrasound, endoscopy, computed tomography, or magnetic resonance imaging to determine if chemotherapy drugs are effective in treating cancer.
    • The other tests that are needed depend strictly on the type of chemotherapy drug used.
      For example:
      • a cardiological examination is performed prior to the administration of doxorubicin,
      • kidney function is checked prior to the administration of cisplatin.
  3.  Once it has been established that the animal is fit for treatment, the drug is administered by an appropriate route (intravenous, subcutaneous or orally).
    • The infusion time for intravenous drugs varies from a few seconds to a full day, depending on the chemotherapeutic agent being administered.
    • Meetings with chemotherapy are often planned in such a way that the pet is left at the clinic for a few hours or for the whole day. This allows sufficient time to evaluate the animal, check the blood, and administer the drug. In some facilities, the owners may stay with the patient at all times.
    • Throughout their stay in the oncology facility, patients are monitored for side effects, and if they occur, remedial measures are immediately taken.
    • Blood or urine tests may also be required in the weeks between treatments. The aim is to monitor the effects of therapy and detect adverse effects early.

What drugs are used for chemotherapy in dogs and cats?

Oncological drugs used in therapy

There are over a hundred chemotherapy drugs used in oncology, and more are under development.

They are substances with a different chemical structure and a different mode of action.

As we already know, the main goal of chemotherapy drugs is to inhibit tumor growth by disrupting the cycle of cell division. Depending on the mechanism of action, chemotherapeutic agents are classified into:

  • alkylating drugs,
  • antimetabolic drugs,
  • plant alkaloids,
  • antibiotics,
  • enzymes,
  • hormones and various other agents.

Alkylating drugs

The mechanism of action of drugs from this group is based on the replacement of a hydrogen atom in the DNA chain with an alkyl group.

This breaks the bonds and breaks the bases again, defective or cross-linking. As a result, DNA replication and RNA transcription are disturbed.

As a result, cell division is stopped and tumor growth is inhibited. This group includes the following groups of drugs:

  • Nitrogen mustard derivatives:
    • cyclophosphamide,
    • chlorambucil,
    • melphalan.
  • Triethylene phosphoramide (thiotepa) derivatives;
  • Sulphonic acid derivatives (busulfan);
  • Triazine derivatives (dacarbazine);
  • Nitrosourea derivatives (carmustine, lomustine).

The most common side effects of this group of drugs are:

  • bone marrow depression,
  • gastrointestinal disorders,
  • aseptic hemorrhagic cystitis,
  • disorders of spermatogenesis,
  • hair thinning or alopecia in dogs characterized by continuous hair growth:
    • schnauzers,
    • yorkshire terriers,
    • Afghan greyhounds.
  • in cats, sensory hair loss - whiskers - often occurs.

Nadir, which is the period in which white blood cells (including neutrophils) damage to the maximum, occurs most often between 7.a 10. one day after drug administration.

These drugs are mainly excreted in the urine, and to a lesser extent in the faeces.

Carmustine and lomustine penetrate the cerebrospinal fluid.

Cyclophosphamide (cyclophosphamide) - Endoxan preparation

Cyclophosphamide is the most common of the group of alkylating agents used in veterinary medicine.

It is a non-specific drug for the cell cycle as it exerts cytotoxic effects at many phases of the cell cycle.

It is available in the form of oral dragees or powder for solution for intravenous infusion.

Cyclophosphamide is used on its own or in combination with other medicines to treat the following diseases:

  • lymphoma,
  • leukemia,
  • myeloma,
  • mast cell tumor,
  • venereal tumors in dogs.

Administration restrictions:

  1. Cyclophosphamide can cause hemorrhagic cystitis and is therefore contraindicated in this condition. When glucocorticoids are administered in a chemotherapeutic protocol, the accompanying polydipsia-polyuria (i.e. increased thirst and urination) reduces the incidence of hemorrhagic cystitis, however, when it occurs, it is necessary to temporarily stop chemotherapy.
  2. It must be activated by hepatic microsomal enzymes, therefore its administration in animals with hepatic insufficiency is avoided.
  3. The tablets must not be divided.
  4. In cats, it can be administered intraperitoneally.


  • 50 mg / m2 orally every other day or 250-300 mg / m2 every 3 weeks.

Chlorambucil - preparation Leukeranhlorambucyl - preparation Leukeran

Available in the form of 2 mg tablets.

Used in:

  • chronic lymphocytic leukemia,
  • lymphoma,
  • polycythemia vera.


  • 2-8 (-10) mg / m2 orally every other day or weighing dogs

Melphalan (melphalan) - Alkeran preparation

Available in the form of 2 mg tablets.

Used in the treatment of:

  • myeloma,
  • lymphoma.


  • 1-5 (-7) mg / m2 orally every other day or weighing dogs < 10 kg 0,1 mg/kg.

Busulfan - Myleran preparation

It is a non-phase specific drug, although it has the greatest inhibitory effect on cell growth in the metaphase.

Available in the form of 2 mg tablets.

Used in:

  • chronic myeloid leukemia,
  • polycythemia vera.

Dosage: 2 (-6) mg / m2 orally once daily.

Ifosfamid - Holoxan (powder for solution preparation)

Used in the treatment of lymphoproliferative processes and some cancers.

Dose: 350-375 mg / m2 intravenously every 3 weeks.

Dacarbazine (dacarbazine) - Dacarbazin (powder for solution for injection)

Used in the treatment of lymphoma.

A dose of 100 mg / m2 intravenously every 7 days.

Antimetabolic drugs

Antimetabolic drugs are analogs of purine and pyrimidine bases.

They disrupt the synthesis of nucleic acids (DNA and RNA) by inhibiting the enzymatic function or by replacing normal nucleotides with abnormal molecules, thus causing the genetic code to be misread.

Antimetabolites are specific drugs for the cell cycle phase because they exert a cytotoxic effect at one stage of the cycle - the S phase.

These include:

  • folic acid antagonists (methotrexate),
  • analogs of pyrimidine bases (fluorouracil, cytosine arabinoside),
  • purine base analogs (mercaptopurine, thioguanine, azathioprine).

Side effects that may arise from the administration of these drugs include:

  • bone marrow depression,
  • gastrointestinal disorders,
  • renal tubular necrosis,
  • damage to the central nervous system (manifested by convulsions).

Most of them are metabolized by the liver and excreted in the urine. Some drugs in this group (methotrexate) are metabolized by the bacterial flora of the gastrointestinal tract.

Nadir in this group of drugs is observed between the age of 6 months. a 9. one day after administration of the chemotherapeutic agent.

Methotrexate (methotrexate sodium) - Methotrexat preparation

It comes in the form of tablets (2 mg, 10 mg each) or a solution for injection.

Methotrexate blocks key enzymes necessary for the production of folic acid, which is needed for the synthesis of DNA acid.

Used in the treatment of:

  • lymphoma,
  • leukemia,
  • a venereal tumor,
  • Sertoli cell tumor,
  • osteosarcoma.

Dose: 0.6-0.8 mg / kg (dogs less than 10 kg) or 2.5 mg / m2 orally, intravenously, subcutaneously daily or according to a schedule.

Side effects include:

  • bone marrow depression,
  • vomiting,
  • diarrhea.

Fluorouracil - 5-fluorouracil pre-apparatus (solution for injection)

Used in the treatment of:

  • mammary gland cancers,
  • basal cell tumor,
  • squamous cell carcinoma.

The drug penetrates very well into the cerebrospinal fluid. It must not be used in cats.

A dose of 150 (200) mg / m2 intravenously every 7 days.

Cytarabine (cytarabine) / cytosine arabinoside - Cytosar preparation (lyophilisate for solution for injection)

Used in the treatment of:

  • lymphoma, especially the central nervous system form,
  • acute leukemia.

Dose: 100 mg / m2 subcutaneously for 3-4 consecutive days or 150 mg / m2 twice a day for 2 days or 600 mg / m2 once a week.

Mercaptopurine (mercaptopurine) - preparation Mercaptopurine (50 mg tablets)

Used in the treatment of:

  • lymphoma,
  • leukemia.

Dose: 50 mg / m2 orally every other day.

Tioguanine (thioguanine) - Lanvis preparation (tab. 40 mg)

Used in the treatment of:

  • lymphoma,
  • leukemia.

Dose: 50 mg / m2 orally 2 times a day.

Azathioprine (azathioprine) - Azathioprine preparation (50 mg tablets)

It is administered to induce immunosuppression at a dose of 1-2 mg / kg orally every 24-48 hours.

Anticancer antibiotics

They are natural substances isolated from soil fungi.

They permanently bind to DNA bases, forming stable complexes and leading to the inhibition of further DNA and RNA synthesis.

These include:

  • doxorubicin,
  • epirubicin,
  • mitoxantrone,
  • actinomycin,
  • bleomycin.

The most common side effects:

  • bone marrow depression,
  • gastrointestinal disorders (anorexia),
  • cardiotoxicity,
  • nephrotoxicity (cats are especially sensitive),
  • after extravasation, they cause a very strong local reaction that can lead to tissue necrosis,
  • alopecia.

This group of drugs is given as a slow intravenous infusion, as rapid administration can lead to intense vomiting or even shock.

Nadir is seen between 7 months of age. a 10. one day after administration of the chemotherapeutic agent.

Doxorubicin (doxorubicyn hydrochloride) - Adriblastin formulation in the form of a lyophilisate for solution for injection

Doxorubicin is an anthracycline antibiotic with proven anti-cancer activity in the treatment of tumors in humans, dogs and cats.

It inhibits the synthesis of nucleic acids and cytochrome c oxidase and generates the formation of reactive oxygen species.

The factor that limits the dose of doxorubicin is its toxic effect on:

  • heart,
  • kidneys,
  • stomach,
  • bowels.

It is used in the treatment of:

  • lymphoma,
  • leukemia,
  • soft tissue sarcoma,
  • osteosarcoma.

Dose: 1 mg / kg (in dogs

In cats, 1 mg / kg or 20 mg / m2 every 30 days.

The maximum cumulative dose for a dog should not exceed 120 mg / m2 as an increased risk of cardiotoxicity is predicted to occur at cumulative doses greater than approximately 180-240 mg / m2 (lifetime).

Administration restrictions:

  • The drug is highly cardiotoxic. Heart muscle tissue is one of the most susceptible to damage caused by oxygen free radicals in humans and dogs. Cardiac toxicity of doxorubicin may manifest itself as arrhythmia or as irreversible or life-threatening cardiomyopathy, characterized by diffuse myocardial degeneration, vacuolization and fibrosis. Doxorubicin is therefore contraindicated as an anti-cancer drug in dogs previously diagnosed with heart disease.
  • Strong irritant after extravasation.

Epirubicin (epirubicin hydrochloride) - Farmorubicin (injection solution)

Used in treatment

  • lymphoma,
  • leukemia,
  • soft tissue sarcoma,
  • osteosarcoma.

Cardiotoxic drug!

Dose of 1 mg / kg (in dogs

Mitoxantrone (mitoxantrone) - Mitoxantrone (solution for injection)

It is a synthetic antitumor antibiotic belonging to the anthracenediones group. Molecularly, it is similar to doxorubicin, but has a significantly lower cardiotoxic effect.

Therefore, its use is becoming more frequent, especially in the treatment of breast and prostate cancer, leukemias and lymphomas in humans.

In dogs, mitoxantrone has shown some degree of efficacy in the treatment of:

  • squamous cell tumors,
  • transitional epithelial tumors,
  • lymphomas.

The drug is used on its own in most studies of canine lymphoma, often in cases of exacerbation of the cancer.

The use of mitoxantrone in multi-drug protocols is still under research and so far the effectiveness is poorly understood.

Used in the treatment of:

  • lymphoma,
  • leukemia.

A dose of 3-5.5 mg / m2 intravenously every 21 days; in cats, 6.5 mg / m2 intravenously every 3 weeks. In cats, it can cause seizures.

Plant alkaloids (rosacea alkaloids)

Plant alkaloids interfere with the formation of the mitotic spindle and prevent cell division.

They bind to the microtubule protein that forms the mitotic spindle during metaphase. Vinca alkaloids are specific to the cell cycle phase and act in the M phase.

These measures have minimal effect on the bone marrow and can be used with stronger myelosuppressants.

They are very often used in therapy:

  • lymphoma,
  • leukemia,
  • venereal tumor in dogs.

These include:

  • vincristine,
  • vinblastine.

The most common side effects:

  • Strongly irritating effect after extravasation of the drug (local necrosis),
  • a slight myelosuppression is very rarely observed.

Nadir is seen between 4 weeks of age. a 9. one day after drug administration.

Vinca alkaloids are excreted in the inactive form by the liver via the faeces.

Vincristine (vincristine sulphate) - Vincristin preparation (lyophilisate and solvent for solution for injection)

Used in the treatment of:

  • lymphoma,
  • leukemia,
  • a mast cell tumor,
  • a venereal tumor.

It has a strong irritating effect after extravasation.

Administered at a dose of 0.5-0.75 mg / m2 intravenously every 7 or 21 days.

In cats, it can be administered intraperitoneally.

Vinblastine (vinblastine sulphate) - Vinblastin preparation (lyophilisate and solvent for solution for injection)

Used in the treatment of:

  • lymphoma,
  • leukemia,
  • mammary gland cancer,
  • testicular cancer,
  • a mast cell tumor.

Dose 2 (2.5) mg / m2 intravenously every 7 days.

Vinblastine has a greater hematopoietic toxicity than vincristine.

Platinum derivatives

Platinum derivatives cause cross-linking of DNA strands, disrupting cell growth.

This group includes cisplatin and carboplatin.

Side effects:

  • renal tubular necrosis,
  • gastrointestinal disorders,
  • with extravasation, a strong local reaction occurs,
  • very toxic to cats (especially cisplatin) and therefore must not be used in this species.

Platinum derivatives are excreted through the kidneys.

Nadir in dogs seen between 11 weeks of age. a 14. day.

Cisplatin (cisplatin) - Platidiam preparation (powder for solution injection)

It is a phase nonspecific chemotherapeutic agent specific to the cell cycle.

Used in the treatment of osteosarcoma.

It is highly nephrotoxic.

It must not be used in cats.

Dose of 50-70 mg / m2 intravenously every 3 weeks as a slow drip infusion (25 ml / kg / h.).

Carboplatin (carboplatin) - Carboplatin - solution for injection

Used in the treatment of:

  • osteosarcoma,
  • cancer.

A dose of 300 mg / m2 intravenously every 3-4 weeks; in cats, 200-250 mg / m2 intravenously every 3 weeks.

Other anti-cancer drugs

Asparaginase (asparaginase) - Asparaginase preparation (lyophilisate for solution for injection)

It is an enzyme that breaks down asparagine (a product necessary to synthesize protein), thus depleting its reserves in the body.

Malignant cells lack the enzyme asparagine synthetase necessary to make the essential amino acid asparagine, while normal cells have the enzyme needed to synthesize additional asparagine.

Asparaginase used to treat:

  • tumors of the lymphoproliferative system:
    • lymphoma,
    • leukemia,
  • mast cell tumors.

Anaphylactic shock (if the drug enters the blood vessels) may be a side effect of this medication, so it should only be given by intramuscular or subcutaneous injection.

Dose of 400 j.m./ kg or 10,000 (40,000) units.m./ m2 subcutaneously or intramuscularly every 7 days.

Hydroscurea (hydroxycarbamide) - Hydroxyurea preparation (500 mg capsules)

Hydroxycarbamide inhibits ribonucleic reductase, which in turn interferes with DNA synthesis.

It is used in the treatment of:

  • polycythemia vera,
  • chronic leukemia.

A side effect is bone marrow suppression.

50 mg / m2 orally once a day, weekly once a week; 10 mg / kg daily orally in cats.

Mitotane (mitotane) - Lysodren preparation (500 mg tablets)

It is a cytostatic drug that has been used in the treatment of hyperadrenocorticism.

It destroys the band layer of the adrenal cortex by activating cytochrome p450.

It does not affect the primary tumor of the pituitary gland, but the target organ, the adrenal gland.

The dose of 50 mg / kg orally once a day, weekly once a week.

Piroksikam (piroxicam) tablets 10 mg, 20 mg

Piroxicam is a non-steroidal anti-inflammatory drug which has anti-cancer activity.

It is used in cancers of the bladder (transitional epithelial cancer).

The mechanism of the anti-cancer activity is not fully understood. It is known that its inhibitory effect on cyclooxygenase 2 (COX-2), the excessive activity of which has been observed in numerous neoplasms, plays a role.

In the event of vomiting, the chemotherapy drug should be discontinued.

Dose of 0.3 mg / kg orally every other day.

Glucocorticosteroids (prednisone, prednisolone)

In chemotherapeutic protocols, they have the properties of "weak chemistry ". In multi-drug regimens, they prevent the side effects of chemotherapy (e.g.in. tumor lysis effect), but they themselves also show an inhibitory effect on DNA synthesis, thus acting as a cytostatic.

They have a beneficial effect in the treatment of lymphoma and mast cell tumors.

In addition to the chemotherapy itself, it should not be forgotten that cancer treatment also includes:

  1. Eliminating the pain.
  2. Administration of symptomatic drugs.
  3. Prevention of possible side effects of chemotherapy.

Are there any studies on anti-cancer drugs?

Many drugs are available for the treatment of cancer, but only a limited number has been shown to be effective.

Agents with potential anti-cancer effects are evaluated in clinical trials, but before a drug is introduced into therapy, it must pass a standard set of efficacy and toxicity tests.

  • Phase I of drug research concerns the evaluation of new drugs in vitro and in vivo, determining cytotoxicity (preferably cancerous). The dog and cat are not routinely used as experimental models, so even if a drug is approved for human use, the dose and any possible species-specific reactions are often not known for these animals.
  • Phase II involves testing the drug on a wide variety of cancers in hopes of detecting which tumors might respond. Such drugs are often used in animals that have a high tumor burden and conventional therapy has failed.
    It is enough that there is any measurable disease regression to warrant a phase III trial.
  • Phase III is a clinical trial designed to compare the relative value of different treatment regimens. Basically, the new treatment is compared with the currently available standard treatment that serves as a control group. Patients are carefully selected so that differences in response can be attributed to therapy, not differences in the patient population.

Human drugs are used in veterinary oncology, but the doses of chemotherapeutic agents are many times lower than in humans.

In human medicine, there is a struggle to cure the patient or to have a long-term remission of the disease. In animals, chemotherapy is rarely curative, and the comfort of the dog or cat is paramount.

The identification and development of effective new anti-cancer drugs is an ongoing process. There is constant research into new generation drugs with different modes of action.

The greatest attention is focused on such preparations that would be maximally toxic to cancer cells with minimal toxic effects for patients.

Research is currently underway on the use of monoclonal antibodies, anti-cancer vaccines or drugs that inhibit tumor angiogenesis.

What is monotherapy and combination chemotherapy?

Chemotherapeutic drugs can be administered in a variety of configurations.


Monotherapy is the administration of one specific drug. Doing so significantly reduces the risk of toxicity as only one cytostatic is used.

The cost of chemotherapy treatment is also substantially lower.

In fact, monotherapy is often used in animals because of the financial constraints of the owners.

A serious disadvantage of this type of treatment is the fact that when only one drug is administered, there is a significant risk of developing resistance from neoplastic cells, and thus the effectiveness of such therapy decreases.

The use of single agents to treat the tumor may therefore reduce remission and survival time (compared to combination therapy).

Sequential chemotherapy

The inconvenience of monotherapy prompted the use of sequential drug therapy with the administration of single drugs until the tumor does not respond, and then "switching" to another class of anticancer drugs.

Sequential drug therapy is easy to administer and inexpensive, but survival times are short and prolonged remissions are rare.

Combination chemotherapy

Combination chemotherapy is the administration of several cytostatic drugs from different groups according to a specific administration schedule.

By choosing drugs from different classes and using them simultaneously, we hope to kill cells at different stages of the cell cycle.

Such a "circling maneuver" thus reduces the possibility of cancer cells surviving and obtaining resistance to the beneficial effects of agents, and thus maximizes the anti-cancer effect.

No wonder then that combination chemotherapy is recognized as the most effective treatment method.

However, there are situations where this type of therapy is not necessarily better.

For example, in canine venereal tumors, it was shown that the more costly and toxic combination therapy of cyclophosphamide, vincristine and methotrexate was not more effective than vincristine used as a single agent.

Unfortunately, combination chemotherapy also has some disadvantages.

The simultaneous use of many drugs is expensive, and the risk of toxic effects of cytostatics on the body increases significantly.

However, increased therapeutic efficacy and slower development of drug resistance in most cases reward the costs incurred.

When using multi-drug therapy, certain factors are important:

  • Each individual drug should have anti-tumor activity specific to a particular malignant cell line. In other words, the tumor must be sensitive to each of the drugs used.
  • All drugs should be used in the maximum tolerated doses.
  • Drugs from the same group are not combined.
  • The combined effects of multiple doses of chemotherapeutic drugs can cause permanent side effects; treatment should be discontinued if the risks outweigh the benefits.
  •  Certain strong drugs (e.g. Doxorubicin) can only be used a limited number of times before the risk of toxicity to some organs becomes too great.
  • Other medications may not be suitable because of the reactions or debilitating side effects. You need to anticipate possible side effects and prevent them in advance through appropriate medical treatment (e.g. forcing diuresis, prophylactic administration of antibiotics, administration of hepatoprotective drugs, etc.).
  • Sometimes the cancer develops drug resistance, and the list of effective chemotherapeutic agents may decrease as treatment progresses.

What are chemotherapy protocols / regimens?

A chemotherapy protocol (or regimen) is a treatment plan for a specific type of cancer in which drugs are specially selected for their unique and complementary anti-cancer properties and given in a specific sequence and schedule.

There are many factors the oncologist will consider when choosing a protocol for a given patient, including the type and extent of the cancer, the nature of the drugs, published evidence of their effectiveness, any potential side effects, and the animal's medical history and general well-being.

Your dog's breed can also influence the protocol; some breeds with the MDR1 mutation are intolerant of some chemotherapeutic agents.

Cancer affects each animal differently and, in addition, patients sometimes have individual responses to chemotherapeutic agents, so chemotherapy protocols often need to be individualized.

If the physician does not see a response within a certain period of time, the medication may be ineffective and a different protocol or treatment discontinuation may be required.

The oncologist may even develop a protocol that is not standard but is the best way to treat your pet.

Will the chemotherapy make my dog ​​/ cat feel unwell??

Will the chemotherapy make my dog ​​/ cat feel unwell??

Many people initially hesitate to use chemotherapy to treat their pet's cancer because they don't want to lower their quality of life.

The owner may be concerned that the treatment will cause the pet serious side effects and make the pet feel unwell.

These concerns are fully justified.

After all, administering anti-cancer drugs in doses that are sufficient to kill the cancer cells also causes some normal cells to die. Thus, toxicity is a predictable outcome of chemotherapy and to some extent unavoidable.

Answering the question:

yes, chemotherapy can cause side effects in dogs and cats.

However, given that the main goal of oncological treatment in animals is to provide them with a good quality of life for as long as possible, all measures are taken from the very beginning to prevent or alleviate the onset of side effects of chemotherapy.

The tumor is treated as aggressively as possible, but not at the expense of the animal's quality of life.

If a dog or cat begins to experience significant side effects from chemotherapy, the treatment plan is revised.

Fortunately, most animals tolerate chemicals better than humans. By selecting the right drug and dose, as well as protocol planning, the risk of life-threatening toxicity can be avoided.

Generally, dogs and cats receiving chemotherapy feel normal on the day of dosing.

Maybe 3-5 days later, the owner will notice that the pet is feeling worse.

May be lethargic, have poor appetite (most often due to nausea), and may experience temporary vomiting or diarrhea.

As a rule, the animal will feel well within 24 to 48 hours, and symptoms will subside until the cycle is continued with the next dose of the drug.

You should report any symptoms you notice to your doctor with each dose of chemotherapy, as a change in the animal's therapy may be warranted on this basis. If both the doctor and owner agree that the pet's quality of life is good, and there is evidence that the chemotherapy is working, treatment is continued.

However, remember that each animal is different.

A small percentage of pets are more sensitive to chemotherapy, and it is impossible to predict which animals will experience severe chemotherapy toxicity.

If severe toxicity occurs, hospitalization for several days at a veterinary clinic may be required to help the patient recover.

Fortunately, the need for pets to be hospitalized for chemotherapy-related side effects is rare, and some studies show that hospitalization is necessary in less than 10% of patients receiving chemotherapy.

Since the main goal of chemotherapy is to give your pet a good quality of life, if your pet experiences significant drug-induced toxicity, the dose of the drug is reduced or the drugs causing side effects are changed.

In addition, if the side effects associated with chemicals are really bothersome, you can stop treatment at any time.

Many dogs and cats are able to complete chemotherapy protocols without experiencing any toxicity or experiencing only mild symptoms.

What are the common side effects of chemotherapy?

Side effects of chemotherapy

As we already know, rapidly dividing cells are more susceptible to the deadly effects of anti-cancer drugs.

Unfortunately, drugs used in treatment cannot distinguish between neoplastic and healthy cells.

As a result, the destruction of rapidly dividing cells in the bone marrow and the digestive tract becomes a problem.

In addition, some medications can damage the reproductive tract (not a problem in neutered or spayed dogs and cats); others may affect specific organs, such as the heart, liver, kidneys and bladder, and therefore require frequent monitoring.

The cells of the bone marrow, lymphatic system, gastrointestinal tract, epidermis and reproductive organs are particularly sensitive to the damaging effects of cytostatics.

Even if no significant contraindications to the administration of cytotoxic drugs were found at the beginning of the therapy, various complications may arise during the course of treatment.

In such a situation, the first step is to determine whether the animal's symptoms are related to the chemotherapy or are due to the progression of the cancer.

It is also possible that they have no relation to the above and are accidental (e.g. stress or food poisoning).

Once the disorders appear, it is important to determine whether and to what extent they complicate the course of treatment and how their effects can be minimized.

Sometimes they are so serious that the doses of cytotoxic drugs should be reduced, the type of drug should be changed or the administration of chemicals should be withdrawn completely for some time. In other cases, it is enough to introduce symptomatic treatment (e.g. antiemetic, antidiarrheal).

In the event of complications that significantly affect the course of chemotherapy, it may be necessary to reassess the prognosis and plan further treatment.

Fortunately, most animals receiving chemotherapy are usually mild. Animals experience less severe symptoms from drug side effects because lower doses of drugs are used in veterinary medicine and there are not as many different combinations and combinations of many different drugs as in human medicine.

Chemotherapy-related side effects usually occur over a predictable period of time, allowing for an early initiation of treatment to prevent or reduce your pet's clinical symptoms.

In addition, unpleasant symptoms are usually temporary and usually disappear within a few days (this is the period during which chemically damaged cells regenerate).

Side effects can be:

Local, related to the route of drug administration

Local side effects are most often associated with the strong irritation of drugs that leaked outside the vein at the time of administration (this is called. drug extravasation).

These changes can be inflammatory or necrotic, and the drugs causing them include:

  • vincristine,
  • cisplatin,
  • doxorubicin,
  • mitoxantrone.

Depending on how much of the medicine was released into the surrounding tissue, the lesion could be:

  • redness,
  • baldness,
  • ulcers
  • even deep necrosis, reaching the periosteum.

It is accompanied by a very strong pain, the animal is interested in this place and licks it intensively.

Generalized, involving various organs (most often the gastrointestinal tract, but also the urinary system, heart, pancreas, liver).

There is a risk of shock when cytotoxic drugs are administered intravenously or intraperitoneally, therefore it is necessary to observe the animal for several to several dozen minutes after administration of the drugs.

Gastrointestinal side effects

The toxic effects of cytotoxic drugs on the gastrointestinal tract of animals usually include:

  • decreased appetite,
  • nausea,
  • vomiting,
  • altered stool consistency,
  • diarrhea.

These effects can be mild, moderate or severe.

In most cases, these symptoms are mild and usually resolve on their own or with symptomatic treatment by mouth.

Although rare, some dogs and cats may develop more serious symptoms, such as persistent vomiting or severe (even bloody) diarrhea requiring hospitalization and fluid therapy.

In many cases, the side effects of chemotherapy on the gastrointestinal tract are not evident on the day of treatment.

Usually they appear as a result of inflammation of the gastrointestinal mucosa, often in the second year of life. to 5. day after receiving chemotherapy and they disappear within 1-2 days. The exceptions are drugs such as cisplatin and doxorubicin, which can induce vomiting already during the infusion, therefore prophylactic antiemetics are used during their administration.

The most common cause of vomiting is stimulation of the vomiting center in the spinal cord extended by drugs and / or stimulation of peripheral receptors in the gastrointestinal tract and the vestibular apparatus.

The drugs that most commonly cause nausea and vomiting are:

  • cisplatin,
  • doxorubicin,
  • mitoxantrone,
  • methotrexate,
  • cyclophosphamide,
  • and sometimes also vincristine (depending on individual properties).

The use of L-asparaginase may cause pancreatitis with associated gastrointestinal symptoms. Therefore, it is recommended that dogs have specific pancreatic lipase levels checked prior to administration of this drug.

Side effects related to bone marrow suppression

The bone marrow is responsible for the production of white and red blood cells and platelets.

Disorders of the hematopoietic system result from the fact that the bone marrow does not regenerate quickly enough or the blood cells undergo accelerated decomposition.

The reduction in blood cell counts may affect all blood cells or individual cell lines.


Immunosuppression is due to decreased white blood cell counts and impaired humoral and cellular immunity.

After administration of cytotoxic drugs, leukocyte levels may temporarily decrease.

In general, 5 are seen as having the lowest white blood cell count.-7. day after the dose of chemotherapy, but the time may vary depending on the drug used. The fall in leukocyte counts may be mild, moderate or severe.

White blood cells are very important in fighting infection.

Bone marrow suppression by chemotherapy drugs, which causes a drop in the number of white blood cells, can make you more prone to infections.

The infection is usually endogenous, i.e. it comes from the animal's organism (e.g. its source is bacteria, usually found in the intestines, mouth, skin).

Severe infections may require hospitalization for intensive supportive care, including intravenous fluid therapy and antibiotics.

However, not all animals with a low white blood cell count will develop an infection. In fact, most pets with leukopenia may feel fine and not have any clinical symptoms.

However, if an infection does develop, it can cause a fever, the pet may refuse to eat, and be apathetic.

Fortunately, suppression of the immune system is short-lived and is reversible when chemotherapy is stopped. As the body regenerates cells very quickly, even if the animal experiences a very strong drop in their levels, the numbers usually return to normal within 24-48 hours.

White blood cell counts are carefully monitored during treatment in all patients receiving chemotherapy. This allows us to adjust the dose or prescribe antibiotics as indicated to avoid the need for hospitalization.


Leukocytes of great importance are neutrophils, i.e. neutrophils, because they are the first line of defense (they protect against infections and prevent sepsis), and additionally have a very short survival time.

Due to the fact that under normal conditions neutrophils predominate in the blood picture, the decrease in the total number of granulocytes is mainly manifested by neutropenia.

It is of great clinical importance. It is the neutrophil count that is the parameter that the doctor pays special attention to when performing blood tests before administering chemotherapy.

It is not good to have too many of them, as this could be an infection or suggest that chemotherapy is ineffective; in turn, if there are too few of them, it is also a problem - then you need to reduce the dose of the chemotherapeutic agent or even completely postpone its administration, and sometimes even introduce antibiotics prophylactically.

As a rule, the number of neutrophils drops in 5 weeks. - 7. the day after administration of chemotherapy, with some variation from patient to patient and depending on the medications administered.

Nadir - the time when the drug is most active - is variable and can manifest as the strongest neutropenia: with doxorubicin, it is usually between 7. a 10. day, in the case of cisplatin between 6. a 15. day.

The exceptions are, among others, lomustine and carboplatin, after administration of which neutrophil nadir may occur after 2 or 3 weeks.

Thrombocytopenia (thrombocytopenia)

Tombocytopenia occurs when the production of platelets is reduced or their destruction is accelerated.

This is a relatively common side effect of chemotherapy and is not usually of concern as long as the platelet count does not fall below 50 G / l.

Thrombocytopenia can also result from autoimmune processes accompanying tumors (paraneoplastic syndromes).

If a patient experiences a severe drop in platelets (below 10 G / l), he may experience spontaneous bleeding and symptoms of disseminated intravascular coagulation.

In such a situation, it is recommended to determine the concentration of fibrinogen degradation products (FDP), which under physiological conditions should not exceed 10 μg / ml.

Anemia with chemotherapy

Anemia (low red blood cell counts) is a relatively rare complication of chemotherapy and, when it occurs, is usually mild.

As a rule, it also occurs later than neutropenia and thrombocytopenia.

Much more common causes of neoplastic anemia are bone marrow involvement and decreased erythropoiesis (leukemia) or increased blood loss (e.g. due to bleeding into body cavities caused by tumors).

In the course of certain cancers (e.g. adenocarcinomas, lymphomas, mast cell tumors) iron deficiency anemia is possible, which is the result of prolonged asymptomatic gastrointestinal bleeding caused by tumors.

Hair loss during chemotherapy

Unlike people receiving chemotherapy, hair loss in dogs and cats is usually very little.

Cats tend to lose their whiskers, and long-haired cats may lose their coat.

Mild hair thinning may occur in dogs.

Areas where hair is cut or shaved during treatment (e.g. for surgery or cannulation, or for ultrasound examination of the abdominal cavity) may grow back very slowly.

Although severe hair loss is rarely seen in dogs, some dog breeds are at higher risk of hair loss due to chemotherapy.

It is most often seen in breeds with a physiologically significant percentage of hair in the growth phase.

In Poodles, Old English Sheepdogs, Schnauzers, Pot, Lhasa Apso, Shih Tzu, Bichon Frize, Yorkshire Terrier, Maltese, and Wirehaired Dogs such as Airedale Terriers and Welsh Terriers, you can expect your pet to lose much more hair in the early stages of chemotherapy.

This is because hair follicle cells in dogs and wirehair or non-shedding cats may be particularly sensitive to chemotherapy.

Hair loss is often most noticeable on the face and tail.

For all pets, hair lost to chemotherapy will regrow when chemotherapy is complete or when the frequency of treatment is reduced.

Occasionally, hair may regrow in a slightly different color, and occasionally regrowth of down hair may be observed.

Hair usually grows back when the dose of medications is lowered.

Extravasation of a chemotherapeutic drug

Some medications need to be delivered directly into a vein just because they can damage other tissues.

If they leak outside a vein during injection, they can be very irritating to the skin and the tissues under the skin.

The effects of extravasation can be very serious and depend on the type of drug and the volume that has entered the surrounding tissue.

Most often you can observe:

  • edema,
  • sore,
  • inflammation.

After extravasation, some chemotherapy drugs can even cause necrosis of surrounding tissues.

Cytostatics that cause severe irritation after extravasation are:

  • vincristine,
  • vinblastine,
  • doxorubicin,
  • actinomycin,
  • mustargen (mechlorethamine),
  • mitoxantrone.

The clinical signs of extravasation are:

  • itching and being interested in the paw, licking or even biting the place where the cannula was,
  • redness and necrosis of the skin and tissues.

These symptoms are usually noticed a few days after the administration of the drug.

With doxorubicin, this time may be longer, even one week after the infusion.

When such symptoms appear, only symptomatic treatment (anti-inflammatory drugs, painkillers, local antibiotics) and the wearing of a collar to prevent licking the wound remains.

In severe cases, surgical intervention may be necessary, and in extreme cases, it may end with limb amputation.

Fortunately, this complication is very rare as all intravenous medications are given by experienced oncologists.

Change in the color of urine

Administration of doxorubicin may cause your pet's urine to turn reddish brown for a few days after administration.

It does happen, and it is not a cause for concern.

Weight loss and chemotherapy

Careful weight control is essential throughout the chemotherapy period. Firstly, because it affects the dosage of drugs, but it is also a very important parameter for assessing the effectiveness of chemotherapy.

Losing weight and progressive wasting (with concomitant lack of appetite) may indicate a lack of disease remission or be the result of too intensive chemotherapy.

Urinary tract disorders (kidneys, bladder)


Some chemotherapy drugs can be toxic to the urinary tract.

Drugs such as:

  • cisplatin,
  • doxorubicin,
  • mitoxantrone,
  • methotrexate.

Therefore, cisplatin cannot be used in cats (its administration is fatal), but in dogs it should be used with caution.

Haemorrhagic aseptic cystitis

Haemorrhagic aseptic cystitis may occur in dogs (occasionally in cats) following long-term administration of low-dose cyclophosphamide (50 mg / m2 tablets orally every other day).

Cyclophosphamide is metabolized in the liver, and one of the metabolites is acrolein, which, with prolonged contact with the bladder wall, may cause irritation and inflammation, and consequently bleeding.

The most common clinical symptoms are:

  • urge to urinate,
  • blood in urine,
  • dropping.

Sometimes symptoms go on for weeks before you feel better.

Haemorrhagic cystitis occurs in approximately 10% of patients taking cyclophosphamide.

Heart muscle damage

Doxorubicin, apart from the effects on the urinary system, shows mainly high cardiotoxicity.

This drug can accumulate in the heart muscle, leading to its degeneration and fibrosis.

The cardiotoxicity of doxorubicin is found primarily in dogs and results in the development of dilated cardiomyopathy accompanied by congestive heart failure.

This is very serious because cardiomyopathy is incurable.

Toxic effects of doxorubicin on the heart muscle may be acute (i.e. occur at the time of drug administration) or, more often, chronic (i.e. cumulative cardiotoxicity) - then it results from the total amount of doxorubicin ingested by the animal during its entire life.

It is assumed that the total dose of doxorubicin that a dog can ingest in its lifetime without harming the heart muscle is 240 mg / m2 (approximately 8 therapeutic doses).

However, a total cumulative dose of 180 mg / m2 (i.e. 6 doses of 30 mg / m2 each) should not be exceeded.

Chemotherapy neurotoxicity

Very rarely, neurotoxicity (i.e. the damaging effect of a chemotherapeutic agent on the nervous system) has been observed in dogs and cats.

Nervous symptoms are more likely to result from accompanying metabolic disorders (hepatic encephalopathy) or the progression of the neoplastic disease than from the action of chemotherapeutic drugs.

A highly neurotoxic drug (especially for cats) is 5-florouracil.

It causes:

  • loss of sight,
  • cerebellar incoherence,
  • agitation,
  • muscle tremors,
  • eventually death.

Therefore, the drug for this must not be used in cats.

Similar symptoms may appear in dogs after its administration, but much less severe, reversible and not fatal.


Liver cell damage due to chemotherapy has been observed in approximately 7% of patients taking lomustine, and it is this drug that is primarily responsible for side effects related to the liver.

Lomustine is used for:

  • lymphomas,
  • mast cell tumors,
  • histiocytic sarcomas.

Anaphylactic reaction

As with any medication, a severe immediate reaction can occur with chemotherapy, but this is extremely rare.

Drugs in which anaphylactic reactions have been observed include:

  • L-asparaginase,
  • doxorubicin,
  • paclitaxel,
  • cisplatin,
  • cytarabine.

The route of administration largely affects the risk of anaphylactic reaction.

Asparaginase should be administered intramuscularly or subcutaneously - intravenous administration may cause anaphylactic shock. With this medicine, the likelihood of a hypersensitivity reaction also increases with the number of doses administered.

Shock may also occur when the intravenous administration of doxorubicin or cisplatin is too rapid. These drugs are administered as slow drip infusions during which basic parameters are monitored (mucosa color, heart rate and respiration).

Another type of shock reaction is acute tumor lysis syndrome, which may (occasionally) be observed especially when treating lymphoma in dogs.

It usually occurs shortly after the administration of chemotherapeutic drugs (several to several hours) as a result of the rapid breakdown of cancer cells.

The clinical symptoms are:

  • bradycardia,
  • apathy,
  • vomiting,
  • diarrhea (with some blood),
  • shock.

Symptoms of anaphylactic shock include:

  • itching,
  • reddening,
  • swelling of the face or mucous membranes,
  • elevated temperature,
  • dyspnoea.


Mild lethargy is a common side effect of chemotherapy. About 3 to 6 days after administration of the cytostatics, the animal may be sleeping more or less interested in playing.

This is not a cause for concern and should go away within a few days.

However, if the animal appears to be very lethargic (that is, it does not get up to eat, drink and take care of physiological needs), contact your veterinarian immediately.

Increased hunger / thirst / urination

These are not side effects of chemotherapy drugs, but are a side effect of some drugs when used in conjunction with chemotherapy.

  • Prednisone - This is a steroid that is often used to treat cancer and can cause increased urination (volume and frequency), hunger and thirst. Remember that while your pet may seem very hungry from this drug, it does not need any additional food. In fact, many pets tend to gain weight when taking prednisone because their owners feel they need more food. Since the steroid also causes the animal to produce more urine, do not limit its water intake as this can lead to dehydration. Also, do not let your pet drink too much as it may cause vomiting.
  • Furosemide - this drug is a diuretic, which means that it causes an increase in urine production and, consequently, your pet will drink more. If you are giving furosemide to your dog, remember to leave more water and allow extra walks to allow the pet to urinate. Furosemide is often recommended in dogs if they are receiving cyclophosphamide, which can potentially cause sterile cystitis. Furosemide is not prescribed to cats, but they will be given fluids to flush their bladder. The increase in drinking and urination helps to empty the bladder and protects it from infection.

How to prevent side effects from chemotherapy?

Although animals are given lower doses of chemotherapy, this does not mean that the animal will not experience side effects from the treatment.

Common are:

  • changes in appetite,
  • diarrhea,
  • lethargy,
  • allergic reactions,
  • and other side effects.

Fortunately, there are many options to help ease your pet's side effects while treating him.

Prevention of nausea and vomiting

To prevent significant nausea in the animal, antiemetics are used, which can be used as needed.

There are several different classes of medications available that are usually of great help in relieving the gastrointestinal side effects of chemotherapy.

Prophylactic administration of antiemetics may be recommended:

  • in patients already suffering from gastrointestinal disturbances and accompanying clinical symptoms;
  • in patients with gastrointestinal symptoms resulting from cancer (often in lymphoma, leukemia);
  • in patients who developed severe symptoms after the first dose of chemotherapy;
  • always before serving:
    • doxorubicin,
    • cisplatin,
    • actinomycin,
    • possibly also carboplatin and mitoxantrone.

The most important steps that can help prevent stomach symptoms are:

  • Administration of antiemetic drugs prior to administration of cytostatic drugs:
    • maropitant 2 mg / kg,
    • butorphanol 0.4 mg / kg intramuscularly,
    • metoclopramide 0.2-0.5 mg / kg intravenously or subcutaneously;
  • administration of chemotherapy by slow drip infusion (especially doxorubicin, cisplatin);
  • avoiding excessive stimulation of the labyrinth (car journey) immediately after administration of drugs.

Prevention of infection

When a chemotherapy drug known to have a high potential for bone marrow is used, complete blood counts are checked a few days after administration.

If the white blood cell count is low but the animal is doing well, antibiotics are prescribed as a preventive measure.

Subsequent doses of chemotherapy are adjusted based on the results of the morphology.

While on chemotherapy, allow your dog to do what he usually does, but use common sense and avoid known dangers such as parks full of dogs.

In moments of reduced immunity of the pet, try to limit walks, give cooked food, do not bathe the dog and do not expose it to contact with other (especially unknown) animals.

Prevention of thrombocytopenia

In order to minimize the risk of thrombocytopenia, glucocorticosteroids are administered: prednisone at a dose of 1-2 mg / kg orally 1-2 times a day.

Vincristine is a cytotoxic drug that stimulates megakaryocytosis. If there is thrombocytopenia caused by the use of other cytostatics (e.g. doxorubicin, cyclophosphamide), the administration of vincristine is not interrupted.

Prevention of extravasation of the cytostatics

The veterinarian is particularly careful when administering doxorubicin, vincristine, vinblastine or actinomycin.

In patients who receive regular chemotherapy, the veins lose their elasticity over time and the skin over them becomes thick and hard. Therefore, it is extremely important to take care of the professional installation of the cannula and prevent problems related to its piercing.

For this reason, blood for laboratory tests should not be taken from the valuable veins on the limbs, but from the jugular vein.

Prior to administration of the cytostatics, the intravenous entrance is checked and the patient is constantly monitored.

If doxorubicin is administered, cats should be restrained pharmacologically to prevent movement. It is recommended that restless dogs are also sedated prior to administration of the chemotherapy, which reduces their mobility and minimizes the risk of "venipuncture" from the vein.

If you notice any redness or inflammation in the area around the injection site, see your doctor immediately.

Prevention of nephrotoxicity during chemotherapy

Special precautions are taken when administering cisplatin.

A kidney function test must be performed prior to administration of this chemotherapeutic drug.

The intravenous infusion of the drug is spread over three days:

  • On the first day, physiological fluids (0.9% NaCl, multi-electrolyte fluid, Ringer's fluid) are administered intravenously in the amount of 20-50 ml / kg in order to adequately hydrate the patient.
  • On the second day, a slow infusion of cisplatin with fluids is used.
  • On the third day, IV fluids are administered again to force diuresis.
  • After one week, kidney function is checked again.

With other cytostatics (doxorubicin, mitoxantrone and methotrexate), such restrictive measures are not required, but adequate hydration of the patient is also necessary.

Intravenous fluids are administered in an amount of 20-50 ml / kg with each administration of these drugs. In this way, diuresis is forced, which prevents the build-up of drugs in the renal pelvis and bladder.

Prevention of hemorrhagic cystitis

Cyclophosphamide is excreted most intensively within 48 hours after administration.

In order to reduce the risk of haemorrhagic aseptic cystitis, it is recommended to use higher doses of the drug (300 mg / m2 intravenously) at greater intervals (every 3 weeks) together with intravenous fluid infusions on the day of chemotherapy (20-30 ml / kg).

Activities that can be performed by the pet's guardian:

  • administering cyclophosphamide in the morning to give the dog sufficient opportunity to empty the bladder throughout the day,
  • simultaneous administration of furosemide to increase diuresis,
  • ensuring constant access to fresh water and encouraging drinking,
  • more frequent walks with the animal (even every 2 hours), which stimulates urination and prevents irritation of the bladder mucosa,
  • regular urine testing with a strip to detect hematuria early.

Prevention of cardiotoxicity

Before each administration of doxorubicin, the patient should be thoroughly cardiologically examined (ECG and ultrasound of the heart) in order to exclude possible dysfunction of the heart muscle.

The indicator that may warn against the development of clinical heart failure is the decreased contractility of the heart muscle.

Cumulative cardiotoxicity may occur in patients predisposed to dilated cardiomyopathy (Dobermans, Boxers, Bernardines, Caucasian Shepherds, Mastiffs) or in dogs with reduced contractility of the heart muscle, even at doses lower than 180 mg / m2, cumulative cardiotoxicity may occur.

  • In situations where there are contraindications to the administration of doxorubicin, it is often possible to replace the drug with another. For example, in osteosarcoma, carboplatin may be administered in place of doxorubicin.
  • Doxorubicin is administered with particular caution in patients predisposed to cardiomyopathy.
  • In dogs at risk, dexrazoxane may be used prophylactically when administering doxorubicin. It prevents the toxicity caused by anthracyclines. It is administered at 10 times the dose of doxorubicin by slow intravenous infusion over 10 minutes. Unfortunately, the high price limits its use and increases the cost of chemotherapy.

Prevention of hepatotoxicity

Since lomustine is responsible for hepatotoxicity associated with chemotherapy, a serum biochemical test with determination of alanine aminotransferase (ALT) activity should be performed before each administration (apart from morphological examination).

  • In treated patients in about 50% of cases the ALT level is elevated, often even several times above the upper limit of normal.
  • If the patient is well and there is no evidence of hepatic insufficiency and ALT levels are below 5 times the reference value, the drug is usually given. It is also worth introducing supplements containing S-adenosylmethionine and silibin.
  • If ALT is significantly elevated, consider extending the intervals between individual doses of lomustine, e.g. administer the drug every 4-5 weeks, instead of every 3 weeks (if possible - the disease should be in remission).
  • In other cases, lomustine is not administered.

To prevent an anaphylactic reaction

In animals with a tendency to hypersensitivity reactions, a test is performed which consists in administering a small amount of cytostatic drug (1/10 of the dose) and observing the animal for several to several dozen minutes.

In the absence of disturbances, the full dose of the drug may be administered.

  • Before administration of asparaginase, it is recommended to administer diphenhydramine (3-4 mg / kg subcutaneously or intramuscularly).
  • After rapid administration of doxorubicin, mast cell degranulation and hypersensitivity symptoms may occur. Therefore, this medicine is given as a slow (20-30 minutes) infusion into a vein.
  • Patients are always closely monitored while administering their medications, and are also observed for about an hour thereafter.

How to treat the side effects of chemotherapy?

Caregivers need to find out about the potential side effects of the medications they are receiving and how to deal with them.

It can sometimes be difficult to determine whether the symptom observed is due to treatment or to the disease itself.

Symptoms are especially difficult to assess in the early stages of treatment, when there is no baseline.

A day or two of nausea and / or vomiting is not unexpected and is rarely dangerous.

Instead, notify your doctor immediately if your pet is not eating or drinking for a day or more, if vomiting or diarrhea is persistent and the pet may be dehydrated, or if you notice blood in the vomit, urine, or blood in stools.

If your pet has severe side effects, you may wonder about continuing the treatment; remember that the dose may be adjusted or a different drug may be used. Report all your observations and doubts to the oncologist on an ongoing basis.

Management of loss of appetite

Loss of appetite is one of the most common side effects and can occur with a dose of any chemotherapy drug.

Reduced or complete refusal of food may take a day or two and is most often the result of nausea. In this situation, you may need to be given anti-nausea medication.

If your dog or cat refuses to eat, try to feed them frequently in small portions.

It is better to keep your pet on normal (known) dog or cat food, but you may need to introduce a gentle diet to increase their interest in eating. Try to offer him:

  • boiled chicken meat mixed with rice,
  • low-fat yogurt or cottage cheese,
  • cooked egg,
  • soft food for cats or dogs in the form of canned food (best for patients with gastrointestinal problems),
  • baby food (e.g. meat gerberas; choose products that are purely meat and do not contain onions),
  • boiled fish or canned fish can encourage eating due to the intense smell.

If for any reason you need to encourage your pet to drink, it may be helpful to add some low fat, low sodium broth to the water.

Management of weight loss

  • Aroma and flavor stimulation to improve appetite. The palatability of the food can be increased by soaking it, heating it up, or adding liquid fats. It is rarely helpful in cats. Pharmacological stimulation is used more frequently.
  • Pharmacological stimulation:
    •  in dogs, cyproheptadine 3 mg / kg 2-3 times a day,
    •  in cats, diazepam 0.05-0.15 mg / kg intravenously once daily or, if necessary, feeding through a nasogastric tube.

Treatment of nausea and vomiting

Chemotherapy drugs that can make you vomit include:

  • doxorubicin (adriamycin),
  • cisplatin,
  • streptazocin,
  • carboplatin,
  • L-asparaginase.

In most cases, treatment of mild gastrointestinal symptoms can be done at home.

  • If the animal vomits food, let it go for several hours.
    If she also vomits after drinking water, take some water as well.
  • After 4-6 hours, give a small amount of water and / or light food.
  • Provide small amounts of easily digestible meals and encourage your pet to eat.
  • If your pet continues to vomit, be sure to see a doctor who may prescribe anti-sickness medications in the event of reduced appetite and / or vomiting:
    • maropitant 1 mg / kg every 24 hours,
    • ondansetron 0.5 mg / kg every 12 hours for 2-3 days after symptom onset,
    • metoclopramide (provided you do not have diarrhea as this medicine makes your bowels move faster)

In the case of significant dehydration, the patient is admitted to the hospital, where, after diagnostic tests, therapy begins.

Treatment in case of severe vomiting:

  • Fluid therapy (supplementation of deficiencies - Ringer's fluid), often there is also a need to supplement potassium.
  • Administration of centrally and peripherally acting antiemetics.
  • If blood, clots, hemolyzed blood are present in the vomit, it is a sign of gastrointestinal bleeding. At that time, drugs that protect the mucosa and reduce the secretory activity of the stomach are also administered (ranitidine 2 mg / kg orally, intravenously and intramuscularly every 8-12 hours, famotidine 0.5-1 mg / kg orally or intravenously every 12-24 hours, omeprazole 0.7-1.5 mg / kg orally every 12-24 hours).
  • In the case of very persistent symptoms of the digestive system, it is sometimes necessary to determine the hematocrit, total protein and electrolytes and to correct any water and electrolyte disturbances. If there is no improvement, an X-ray of the chest and an ultrasound of the abdominal cavity are performed, and additional tests are performed to exclude accompanying disorders (e.g. pancreatitis, intestinal obstruction, aspiration pneumonia, growths in the digestive tract, etc.).
  • It is recommended to resume feeding as soon as possible (even 12 hours after the last episode of vomiting)
  • In most cases, hospitalization lasts 2-3 days (this is the time needed for the gastrointestinal mucosa to regenerate), and treatment is continued at home for several days.
  • If the gastrointestinal symptoms are severe, usually the dose of chemotherapy is reduced by 15-20%.
  • If symptoms are mild, prophylactic administration of anti-emetic and anti-diarrheal drugs is usually sufficient during the administration of the subsequent chemotherapy.

Treatment of gastrointestinal motility disorders

Gastrointestinal motility disorders, such as constipation or diarrhea, are treated symptomatically.

  • With moderate diarrhea, probiotics and dietary changes can help. Sometimes metronidazole is introduced at a dose of 10 mg / kg every 12 hours orally for 5-7 days. Typically, diarrhea resolves or is reduced approximately 48 hours after taking it.
  • If diarrhea is severe, it is recommended that the fluid and electrolyte balance be restored with intravenous fluid therapy.
  • In the case of secondary disorders of the bacterial flora and diarrhea, antibacterial drugs are administered:
    • trimethoprim potentiated sulfonamides,
    • amoxicillin with clavulanic acid,
    • metronidazole.
  • Drugs stabilizing intestinal peristalsis (drotaverine) and preparations having a protective effect on the intestinal mucosa may be helpful: bismuth salicylate (Pepto-Bismol 1 ml / kg orally every 8-12 hours for 1-2 days).

Management of neutropenia

Clinical management of neutropenia depends on its severity:

  • If the total peripheral blood neutrophil count is between 1.5 and 3 G / L, and the neutropenia is not associated with fever or other symptoms, the administration of cytostatics is suspended until the granulocyte count rises above 3 G / L.
    • In the presence of fever (over 40 ° C), an antibiotic is administered orally, and if there is no improvement, a broad-spectrum antibiotic is given. It is important to observe the animal and monitor its vital signs (temperature, heart rate, respiration).
      The administration of chemotherapeutic agents is resumed when the temperature is normalized and the neutrophils have risen to levels above 3 G / l.
  • In a situation where the total neutrophil count is below 1.5 G / l and in the absence of other clinical symptoms (elevated temperature, rapid breathing, increased heart rate, vomiting), chemotherapy is suspended and antibiotics are administered.
    • If such neutropenia is accompanied by general symptoms (most often fever, apathy, vomiting, diarrhea, haematuria), the animal is hospitalized and constantly monitored for symptoms of septic shock, given fluids and a broad-spectrum antibiotic (intravenously).
      • Symptoms of sepsis in animals:
        • sadness, weakness, loss of appetite,
        • body temperature raised or lowered (but note: normal temperature does not exclude sepsis),
        • tachycardia,
        • hyperemia of the mucous membranes,
        • extension or reduction of capillary filling time.
    • With gastrointestinal symptoms, there is a risk of intestinal sepsis. In such situations, consideration should be given to introducing an additional antibiotic (e.g. 3rd generation cephalosporins, enrofloxacin or metronidazole).
      • The best-acting antibiotics are combinations of penicillins or cephalosporins with aminoglycoside antibiotics, as well as combinations of quinolones with clindamycin or metronidazole.
        In leukopenia, e.g.:
        • ampicillin 10-20 mg / kg intravenously 3 times a day + amikacin 5-10 mg / kg intravenously 3 times a day,
        • enrofloxacin 5 mg / kg subcutaneously twice a day + clindamycin 10 mg / kg intramuscularly twice a day,
        • enrofloxacin 5 mg / kg subcutaneously twice a day + metronidazole 15 mg / kg intravenously twice a day.
    • If myelosuppression is suspected, a complete blood count and urine culture are performed. There may be no leukocytes in the sediment (especially in neutropenia), and asymptomatic urinary tract infections may become a source of sepsis.
    • If the neutrophils do not grow within 48 hours, the recombinant granulocyte growth factor filgrastim is administered at a dose of 2.5-10 µg / kg / day until the neutrophil count rises above 3 G / l.
  • With severe suppression of bone marrow function, the next dose of chemotherapy is reduced by 15-20%.

Management of thrombocytopenia

If the thrombocytopenia is due to autoimmune processes, high doses of glucocorticosteroids are administered before the start of appropriate chemotherapy to induce immunosuppression (prednisone 1-2 mg / kg orally 2 times a day for 24-48 hours, then half of this dose).

In the absence of a reaction, vincristine (0.5-0.7 mg / m2 intravenously) is administered.

In order to maintain immunosuppressive therapy, glucocorticosteroids (prednisone 1-2 mg / kg orally 1-2 times a day) or azathioprine (50 mg / m2 orally once a day) can be used.

In the early stages of DIC, fluids are given and a blood transfusion is performed. In the advanced stages, the prognosis is generally poor.

Management of cytostatics extravasation

If extravasation is noticed at the time of administration, the administration of the drug is discontinued immediately.

  • In the event of extravasation of doxorubicin, epirubicin, actinomycin or mitoxantrone, an attempt is made to draw the extravasated drug into the syringe through a cannula or a needle. Cold compresses are then applied to constrict the blood vessels and reduce drug absorption. If dexrazoxane is available, it should be administered within the next 12 hours after extravasation (at a dose 10 times higher than the administered cytostatics). Drug administration is repeated after 24 and 48 hours. An anti-inflammatory ointment or DMSO is applied to the limb.
  • Treatment is different for vincristine or vinblastine extravasation. The extravasation site can be injected with hyaluronidase (1500 units) or glucocorticosteroids (hydrocortisone) can be administered to the swollen site. Warm compresses are applied to increase blood supply. Some try to dilute the drug by injecting the extravasation site with a large amount of physiological fluid, but this procedure is controversial as it may worsen the condition due to the larger volume of irritating fluid in contact with the tissues.

The patient should be closely monitored for a minimum of one week after extravasation. If the animal begins to lick a limb, an Elizabethan collar should be placed on immediately.

Treatment of hemorrhagic aseptic cystitis

When hemorrhagic aseptic cystitis is diagnosed, the therapy consists of:

  • increased oral fluid intake, sometimes intravenous fluid therapy is indicated;
  • administration of diuretics (furosemide 2 mg / kg orally 2 times a day);
  • administering painkillers and diastolic drugs;
  • if the patient has not received glucocorticosteroids, prednisone should be administered at a dose of 0.5-1 mg / kg orally once a day;
  • in advanced cases, administration of DMSO to the bladder;
  • administration of cytotoxic drugs is suspended until the haematuria is resolved;
  • antibiotics are used when bacteria are found in the urine.

Management of an anaphylactic reaction

When symptoms of an anaphylactic reaction appear with the administration of a cytostatics:

  • drug administration is interrupted,
  • IV fluids (including electrolyte disturbances) and glucocorticoids are administered,
  • symptomatic treatment is applied (counteracting vomiting and diarrhea),
  • in case of cardiac disorders, the work of the heart is monitored.

Adrenaline is administered during shock.

What should I do if I notice something very disturbing?

Dogs and cats experiencing the potentially serious side effects of chemotherapy may be weak and lethargic, may refuse to eat, may have vomiting and / or diarrhea, may have a fever, or may appear confused.

Consultation with a veterinarian is required when:

  • You suspect an infection in your dog / cat. The early detection of infection is important so that antibiotic treatment can be started immediately. Signs of infection can include loss of appetite, vomiting, diarrhea, apathy, or depression. To monitor the infection, you can take your pet's temperature. If it exceeds 39 ° C, contact your doctor. Severe infections may require hospitalization for intensive supportive care.
  • The animal has severe vomiting or diarrhea, bloody diarrhea or lethargy. These are indications for immediate appearance at a veterinary clinic.
  • If the symptoms you notice worsen rapidly in the first 24 hours.
  • When the severity of gastrointestinal symptoms does not improve 48 hours after starting symptomatic treatment.
  • Whenever the condition of your mentee worries you. If you have any questions or concerns about your pet after receiving chemotherapy, call the facility where your pet is being treated and speak to a healthcare professional.

How long will my pet receive chemotherapy?

The length of a particular course of chemotherapy will vary depending on the type of tumor, its stage, the treatment prescribed, and the animal's response.

Some patients receive a specific chemotherapy protocol and no additional treatment is required afterwards. In these animals, it is recommended that the health status of scheduled checkups be monitored in order to detect tumor recurrence.

Detecting a relapse early (that is, before relapse becomes more advanced) provides more treatment options with greater potential for success.

For other types of cancer, animals receive long-term chemotherapy.

In such cases, we administer a specific agent until it is no longer effective in killing cancer cells.

When the cancer becomes resistant to treatment with a certain medicine, you will be given another medicine for as long as possible. In such cases, it is impossible to predict how many doses of a given drug the patient will receive.

Treatment is continued as long as the animal is well and comfortable and is at an appropriate level.

One of the more common cancers treated with chemotherapy is lymphoma.

While chemotherapy for this disease is often very effective, owners of cats and dogs with this type of cancer should be aware that their pets need long-term chemotherapy.

The treatment course for other types of cancer is usually much shorter, with protocols changing from once a week to once a month.

The specific length of your pet's individual treatment course will be discussed in detail at the very beginning of chemotherapy.

Is it safe for me to stay around my pet while on chemotherapy?

Overall, the risk to the person caring for an animal receiving chemotherapy is very low.

Drastic changes to the owner's or their pet's lifestyle due to chemotherapy are not recommended.

This means that it can still live in the house, it does not have to be separated from other domestic animals, the cat can still share the litter box with other cats - in short - function perfectly normally.

Chemotherapy drugs are rarely excreted through the animal's skin, so it is not necessary to isolate pets after surgery.

It is always wise to maintain good hygiene, e.g. wash your hands after playing or clean up after your pet and do not let the pet lick your face.

Part of the cytostatics is excreted in its active form in urine and saliva, most intensively for 24-48 hours after administration.

However, as exposure to chemotherapy drugs can cause serious health problems, some precautions are necessary.

Most chemotherapy drugs leave the body through the urinary tract and / or intestines within 24-72 hours after being given. It is important to avoid contact with your pet's urine or faeces during this time.

  • To reduce exposure to these drugs, try to place your dog and cat in a specific location, away from places where children and other animals often play.
  • Wear disposable gloves to collect feces immediately and put them in a plastic bag.
  • If possible, thoroughly rinse areas where your pet has emptied with running water to dilute any chemical residues.
  • If your dog or cat has an "accident" at home, be sure to wear rubber gloves while cleaning. First remove the debris, then clean the area three times with a mild soap and water solution, using disposable paper towels. Place these materials in a plastic bag and dispose of them in the outer garbage can.
  • For cats, change the entire litter box once a day for the first 2 days after receiving chemotherapy and be sure to wear gloves. Be careful when cleaning the litter box all the time your cat is receiving chemotherapy. Discard the waste in an external container.
  • Dogs should urinate or defecate in rarely frequented areas (i.e. not in the sandbox in the yard, where children play, or in the garden right next to the garden seating set).
  • While it is unlikely that a pet owner will be exposed to significant amounts of chemotherapy as a result of routine treatment, some people are at increased risk if they come into contact with cytostatic residues. Pregnant or breastfeeding women, children, people trying to conceive (both men and women) and immunocompromised individuals should never come into contact with chemotherapy drugs, contaminated urine or feces.
  • Keep medicines out of the reach of children and pets.
  • Always wash your hands after handling medicines or waste.
  • First wash contaminated clothes, towels or bedding separately, and then a second time you can wash them with different clothes.

What precautions should be taken when administering oral chemotherapy drugs to the dog / cat?

  • Always wear gloves when handling chemotherapy pills, and wash your hands thoroughly after completing the administration.
  • In the case of dogs, you can put the pills in the "meatball " of tasty food and give the pill before the pet's meal when it is most hungry. Unfortunately, this does not work for cats, and they often have to "squeeze" a pill down their throat. If you are unsure, ask your doctor to demonstrate how to administer the pill to your pet.
  • Never split or crush pills and never open capsules. This can cause the released aerosol of the drug to float up and cause unnecessary exposure.
  • If your pet spits out the pills and begins to break down or melt, place any medicine in a foil bag and discard. Use paper towels to clean the residue. Wipe the floor three times with a dilute solution of soap and water. Put paper towels and medication in a plastic bag and dispose of them in the outer container. The animal should not be re-dosed as the animal may have absorbed some of the drug already and giving another pill may cause an overdose. Check with your veterinarian if you are in doubt as to whether to give an additional dose.
  • Pregnant or breastfeeding women, children, people trying to become pregnant, and immunocompromised people should never come into contact with chemotherapy drugs.
  • Some people may experience skin irritation if they come into direct contact with chemotherapy drugs. These drugs can also be absorbed through the skin and mucous membranes or inhaled. Exposure to chemotherapy should be minimized for all those who come into contact with these compounds.

How to handle chemotherapy drugs at home?

If you are giving chemotherapy at home, you should take special precautions.

Cytotoxic drugs require special storage, handling and disposal.

  • Store chemotherapy drugs in their original packaging.
  • Do not store bottles with medicines in the kitchen, near food or cosmetics, but out of the reach of children and pets.
  • Some medications require refrigeration.
    When storing chemotherapy drugs in the refrigerator, keep them in a specially marked container, away from your own drugs.
  • Avoid smoking, applying makeup, wearing contact lenses, eating, and chewing gum while working with chemotherapy medications.
  • Do not break or crush the tablets.
  • If you accidentally swallow any of your dog's medications, see your doctor, not a vet who cannot legally provide medical advice to people.

How can I support my pet during chemotherapy?

During anti-cancer treatment, the animal's body has to work harder to maintain good health; not only fights disease, but also repairs damage caused by chemotherapy.

  1. Pay particular attention to the symptoms of pain in your mentee; some animals may hide pain symptoms especially well. Remember that pain causes stress and stress can be detrimental to your overall health and the fight against cancer.
  2. The presence of cancer can cause significant changes to a dog's digestion. There are several general concepts that can be used to provide good nutritional support: give a variety of flavorful and tasty foods; minimize the administration of simple carbohydrates (studies have shown that they are fuel for cancer); eat foods with a high-quality protein source and consider omega-3 fatty acids. Discuss with your oncologist any supplements you are considering giving your dog.
  3. If your pet is being given chemotherapy for a while, he may find that he or she needs different medical treatment as well. Regular vaccinations should not be given during chemotherapy, although anti-parasitic and flea control agents may be given, unless contraindicated with chemotherapy or because of your dog's general condition. Always coordinate regular veterinary care with your oncologist.
    • Vaccination against rabies is a statutory requirement, and your dog may need to be vaccinated even if he is receiving chemotherapy. In such a situation, the oncologist may adjust the timing of the administration of the cytostatics so that it does not interfere with vaccination.

One of the most important aspects of treatment is maintaining a positive attitude and ensuring that the life of the pet and its handler is as normal as possible.

Although clinical reality must be borne in mind, enjoying every moment spent together is a better "therapeutic" approach.

What happens after chemo treatment ends?

It is important that the animal undergoing chemotherapy is periodically checked by a doctor. Most often, the control visit takes place after 1-3 months, and the next ones - usually once a quarter.

This will allow potential problems, such as cancer recurrence or spread, to be detected before it becomes too advanced.

When any abnormalities are identified in advance, treatment options will be more numerous and more likely to be successful.

How much does chemotherapy cost for a dog / cat?

The cost of chemotherapy varies greatly depending on the chemotherapy protocol, animal size, number of treatments, diagnostic tests, and additional treatment (e.g. in case of side effects).

In addition, your pet can benefit from the knowledge of several highly qualified specialists in various fields.

For most types of cancer, many treatment options are available with varying costs. Your veterinarian develops a diagnostic and treatment plan that will fit your budget.

Chemotherapy can be expensive.

The drugs used in veterinary oncology are human drugs, and many of them are very expensive.

The total cost of chemotherapy depends on the duration of chemotherapy, associated procedures and diagnostics, and the disposal of hazardous biomedical waste (including leftover drugs, cannulas and needles used to deliver drugs, gloves, gowns, etc.).

Before starting chemotherapy, ask your veterinarian to estimate the expected costs so that you can assess your financial options, then discuss this with him so that he can offer the best treatment options depending on your budget.

How my pet responds to chemotherapy?

There are realistically few cancers that can be cured with chemotherapy.

Some of them may go into remission (no detectable evidence of disease) or even multiple remissions (such as. with lymphoma).

Others may become static (less or no disease progression).

Unfortunately, we don't have a crystal ball to predict how a dog or cat will respond to chemotherapy.

There are studies available on a variety of cancers in dogs and cats. They often contain statistics such as the median survival time or the side effects of individual drugs.

They can be encouraging or discouraging.

It should be remembered that a disease that is treated in one animal may not be curable in another - for various reasons, such as the location of the disease, the age of the cat or dog and the patient's health, as well as the cost and availability of treatment.

So it can be helpful to review the statistics, whether they are comprehensive or limited, and use them as a guide to weighing the potential risks and benefits of chemotherapy.

Remember - if you decide to undergo chemotherapy for your dog or cat, you can stop it at any time.


Cancer diagnosis can be difficult for pet owners, and the prospect of chemotherapy is very overwhelming. However, the fear that animals will spend most of their final days sick with chemotherapy is unfounded.

Knowing about the anti-cancer effects of chemotherapy and what to expect from these treatments can help pet owners decide if this type of treatment is right for their pet.

It is important for owners of dogs and cats receiving chemotherapy to realize that most cancers treated are not curable.

Many of our patients eventually relapse.

However, most treated animals have an excellent quality of life during, and often after, treatment.

Chemotherapy often provides many extra months, and sometimes even years, of a happy life.

The vast majority of owners say that they do not regret their decision to continue chemotherapy with their pet.

Ultimately, there is no perfect answer to these and other questions that will arise about chemotherapy in animals.

The best you can do is consult with experts for advice, ask questions, educate yourself, and consider options from your vet about how best to care for your dog or cat during cancer treatment.

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