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Urolithiasis in dogs and cats: how to recognize and treat it?


Urolithiasis, that is, the formation of stones in the urinary tract is a problem that is very often diagnosed during a routine urine test.

It is an aftermath crystalluria, that is, the precipitation of crystals within the urinary system.

This disease is very dangerous and the affected animal must be under the constant supervision of a veterinarian.

Most often, stones are located within the bladder (almost 90% of cases), less often in the renal pelvis or ureters. The most dangerous complication of urolithiasis is dysuria due to obstruction of the urinary tract.

  • What are urinary stones?
  • Predisposition to urolithiasis
  • Urolithiasis symptoms
  • Diagnostics of urolithiasis in dogs and cats
  • Treatment of urolithiasis
  • Food for dogs and cats with urolithiasis

What are urinary stones?

The mineral composition of the crystals varies, which is why we distinguish urolithiasis:

  • phosphate - ammonium - magnesium (struvite),
  • oxalate - calcium,
  • cystine,
  • gout.

Struvite crystals are the most common cause of urolithiasis in both dogs and cats.

Their formation is predisposed by the alkaline pH of the urine.

Most often, crystals of this type accompany the occurrence of bacterial inflammation within the bladder, especially when infected with urease-producing bacteria (e.g. Staphylococcus, Proteus, Corynebacterium).

Calcium oxalate crystals (oxalates) are formed when a patient's calcium and oxalate levels are disturbed.

The factors predisposing to excessive precipitation of this type of crystals are:

  • increase in blood calcium levels regardless of the root cause,
  • large amount of animal protein in the diet,
  • acidification of the urine,
  • excessive supply of vitamin C,
  • vitamin B6 deficiency.

Cystine crystals indicate the possible occurrence of anomalies in the structure of the renal tubules (impedance of the reabsorption of amino acids).

Gout stones (otherwise uric acid stones) mainly concern Dalmatians, and their formation is associated with the occurrence of a genetic defect or the presence of a persistent venous duct (ductus venosus).

Predisposition to urolithiasis

Predisposition to urolithiasis

As I mentioned at the beginning of the article, crystalluria predisposes to urolithiasis.

Usually the primary cause of the occurrence of the crystals is incorrect diet.

It is a very important factor insufficient water volume taken up, causing the urine to concentrate excessively.

It is considered that too rarely going out for walks with the dog, rarely allowing urination cause a high risk of disease.

They are not insignificant in cats behavioral causes (stress, anxiety, anxiety), but the most common patients suffering from urolithiasis are castrated middle-aged and elderly males.

In order for a scale to form, a so-called mineralization core is needed.

It can be exfoliated epithelium or a bacterial conglomerate around which crystals accumulate, forming a stone.

The porous structure of the product causes further adherence of subsequent crystals and an increase in the mass of the forming stone.

A stone in the bladder irritates its wall, injuring it, causing the inflammatory process to deepen.

Urolithiasis symptoms

Urolithiasis symptoms

Clinical symptoms of urolithiasis depend on the location of the stone.

The first symptoms that prompt a caregiver to visit a veterinarian are usually:

  • blood in the dog's or cat's urine,
  • dropping (passing small portions of urine),
  • urinating outside the litter box,
  • inability to stop urinating until the next walk.

Stones that are small in diameter often end up in the urethra.

Their sharp edges irritate the delicate walls of the urethra, and as a result - the formation of large inflammation and swelling, as a result of which the urethra becomes obstructed and the stone cannot be excreted.

In such cases, caregivers bring the patient who is unable to urinate, has severe soreness in the back abdomen, which may radiate to the hind limbs.

If a large stone is placed in the ureter or at the opening of the renal pelvis, general symptoms may occur, such as:

  • fever,
  • vomiting,
  • lack of appetite,
  • severe weakening of the body.

Ignoring these symptoms is at risk hydronephrosis.

Diagnostics of urolithiasis in dogs and cats

Diagnostics of urolithiasis

Urolithiasis is diagnosed on the basis of clinical studies.

After careful examination of the patient's health and clinical examination, it is most often ordered urine test.

The pet's handler may try to catch the urine in a sterile container during voiding.

A special cat litter is available for cats to collect urine for examination.

Keep in mind that urine should be delivered for testing within a maximum of 4 hours - over a longer period of time, even in healthy patients, crystals precipitate, which means that the test has no diagnostic value.

A much more reliable sample can be obtained by cystocentesis.

It consists in collecting urine directly from the bladder, under ultrasound guidance. An additional advantage of cystocentesis is the possibility of decompressing the overloaded bladder in the case of complete obstruction of the urethra and bringing temporary relief from the patient's suffering.

During the ultrasound examination, you can see a thickened bladder wall, and in the urine you can observe numerous, small formations with high echogenicity.

The so-called "snow blast effect " is characteristic - when moving the probe, some of the larger mineralizations may rise from the bottom of the bladder.

When performing an ultrasound examination, it is worth paying attention to the appearance of the kidneys.

It is important to determine whether mineralization also occurs in the renal pelvis and ureters.

In the case of suspicion of the presence of stones in the ureters, it is also worthwhile to decide on a control X-ray examination to precisely determine their location. This makes it easier to plan further treatment.

In the tested urine sample, a change in pH, the presence of protein, leukocytes, and a change in specific gravity are often found.

The sediment examination shows numerous epithelial cells as well as crystals - this test allows for the identification of the type of crystals and, as a result, the selection of an effective treatment.

Often you can see streaks of mucus, rolls, and numerous red blood cells.

If bacteria are found, it is good to decide on a urine culture with an antibiogram - this will allow you to accurately determine which bacteria you have to deal with and will help you choose the right antibiotic.

Treatment of urolithiasis

Treatment of urolithiasis

Treatment should be based on the diagnosis.

In addition to removing the urinary stone, the presence of bacteria should also be eliminated.

For this purpose, it is necessary to use a properly selected antibiotic.

Depending on the type of stones, drugs or supplements should be introduced to optimize the pH of the urine (most often it requires acidification, therefore supplements containing cranberry extract, addition of vitamin C or also parsley extract).

It is also important to use antispasmodics and painkillers.

In the event of intense haematuria, it is recommended to use antihaemorrhagics and drugs that increase coagulation.

The mere introduction of pharmacological therapy is not enough, stones and mineralization should be removed from the bladder.

Depending on the severity of the disease and the type of stones, there are several methods and options for this type of surgery.


One method of removing calculus from the bladder is surgery urohydropulsion.

For the procedure, the patient must be anesthetized and catheterized.

A sterile fluid is administered through the catheter into the bladder, which after removing the catheter, flowing out of the bladder, carries small diameter stones with it.

The treatment is possible in dogs and cats with minor mineralization and the crystals with smooth edges (so as not to damage and injure the urethra).

The cost of performing such a procedure may vary from 150 to 300 PLN.


If the mineralization and cell deposits are large, and formed stones are visible, surgical removal of the stones from the bladder is necessary.

The period of convalescence and tissue healing after the procedure is not longer than 14 days, the patient must have a wound protected against spilling.

The treatment can be performed on both dogs and cats.

It allows the removal of large diameter stones and the thorough removal of sediment and crystals from the bladder.

The cost of the cystotomy surgery is from about 600 to 1000 PLN.


Lithotripsy, that is, breaking stones in the urinary tract, performed extracorporeal (using a shock wave generated outside the animal's body), is a very interesting alternative to surgery.

However, it should be noted that the stones that form in cats are much more difficult to break down than those found in dogs.

This method is especially valued in the presence of calculus in the ureter or renal pelvis (i.e. in only 10% of patients) - in such cases effective surgery can be challenging.

Intracorporeal lithotripsy (with an endoscope) is suitable for bladder stones in medium and large breed dogs.

It consists in inserting an endoscope with an appropriate instrument and breaking the stone inside the bladder.

The crushed stone pieces are then removed through the urethra.

Both of these methods are definitely less invasive than surgery, and the recovery period is much shorter. Lithotripsy however, it is offered by few veterinary surgeries and its price is higher than the price of the procedure cystotomy.

Food for dogs and cats with urolithiasis

Food for dogs and cats with urolithiasis

When discussing therapeutic options, one cannot ignore a properly selected diet.

  • In the event of cystine stones is recommended a diet low in protein.
  • In the event of struvites content is important phosphorus and magnesium in meals and lowering urine pH.
  • Regarding calcium oxalates, their formation is inhibited a low-protein, low-salt diet.
    They precipitate less frequently in urine with a slightly higher pH.

Therefore, when selecting food for dogs and cats, it is very important to identify in advance the type of crystals from which the stone is formed.

In most cases, the use of veterinary specialty foods is recommended.

Veterinary diets such as "Urinary " or "c / d " contain additives that acidify the urine and have a diuretic effect.

If crystals are found in the urine, with no visible stone formed and no accompanying inflammation of the urinary bladder, The very introduction of a specialized food can have a therapeutic effect and prevent the further development of the disease.

A properly balanced diet is very important in patients after bladder stones, stabilized and cured of cystitis.

Knowing that your pet has a predisposition to precipitating crystals in the urine, you can prevent relapse and stone formation by following a diet.

If the maintainer is not convinced of commercial pet foods, it is a good idea to seek help veterinary dietitian.

The amount of water drunk by the animal is very important.

This is mainly a feline problem, as dog handlers struggle with a lesser degree of thirst.

An important task of the owner of an animal with a predisposition to urolithiasis is to encourage the pet to drink by:

  • adding water to wet food,
  • soaking dry food,
  • the use of drinkers or a cat fountain.

It is controversial addition of salt to food, because by stimulating thirst, it causes an increase in blood pressure and, as a result, can cause other diseases.

The more water a sick animal takes, the more diluted the urine will be. As a result, the precipitation of the crystals will be much slower and they will be removed from the body faster.


Once the problem with urolithiasis is under control, it may come back, so in addition to following the diet, it is very important to do it regularly performing a urine check up.

This allows for the detection of disease relapse at an early stage, before the onset of clinical symptoms.

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