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Cat hypertension: what are the causes and how to treat high blood pressure?

Hypertension in a cat

Hypertension blood in humans is usually associated with heart disease.

We also associate its occurrence with excessive stress, improper diet, use of stimulants, obesity, etc.

The fact is, however, that animals are often affected by this "ailment".

It is strange, the more so because neither cats nor dogs smoke cigarettes, do not use drugs in the form of coffee or alcohol in excess, the level of stress related to the experience is relatively lower, and obesity affects them relatively less often than people.

So why is hypertension often diagnosed in cats, especially in the elderly??

What diseases accompany cats and how to deal with high blood pressure in cats?

I answer these questions in the following study. You will also learn:

  • How to measure the pressure of a cat.
  • What are the most common causes of hypertension in cats.
  • How cat hypertension is treated.
  • Blood pressure
  • How to measure the pressure of a cat?
    • Direct methods
    • Indirect methods of measuring pressure
  • How blood pressure is measured in the office?
  • What is cat hypertension?
  • Hypertension in cats
  • The most common causes of hypertension in cats
  • Clinical consequences and symptoms of cat hypertension
    • Progressive Chronic Kidney Disease
    • Complications in the cardiovascular system.
    • Retinopathies
    • Neurological complications
  • Indications for the study of pressure in cats
  • When do I recommend having a cat's blood pressure measured?
  • Treatment of hypertension in cats
    • When to treat a cat's hypertension?
    • Drugs for hypertension in a cat
    • Diet of hypertension in the cat
  • Prognosis

Blood pressure

Blood pressure is nothing more than the force exerted by blood against the wall of arteries as the heart contracts and relaxes.

At the moment of heart systole, when the blood volume is pushed onto the circumference of the body, blood pressure is the highest, while during diastole - it is lowest.

Normal blood pressure in healthy cats is 120/80 mmHg.

Why do we need this knowledge?

Blood pressure measurement in office conditions is an important test, especially in the presence of other diseases in the cat.

When blood pressure rises above the reference value for some reason and remains at this level for a long time, it means that the body is undergoing harmful processes that it cannot fully cope with.

Self-regulation of the blood pressure level is conditioned by a number of mechanisms responsible for maintaining its correct values.

So if there is hypertension, it is in most cases a sign of some dysfunction.

How to measure the pressure of a cat?

Pressure in cats is measured using direct and indirect methods.

Direct methods

So-called direct methods (intravascular) pressure measurements are the "gold standard", but due to their invasiveness, their use is much less frequent.

The measurement is performed using an arterial catheter placed in the femoral artery.

Indirect methods of measuring pressure

Indirect methods are:

  • easier to apply,
  • not requiring sedation,
  • less stressful for patients,
  • technically simpler.

They consist of placing an inflatable cuff on a limb or tail of an animal, which is then inflated with air until the pressure exceeds the systolic pressure.

This causes the artery directly under the sleeve to pinch.

Then, as air gradually leaks from the cuff, changes in pressure are detected.

Depending on the measurement technique, the following values ​​are obtained:

  • systolic,
  • diastolic,
  • average blood pressure.

Methods for indirect blood pressure measurement include:

Auscultation

This technique - commonly used in humans, in animals is quite difficult to carry out

Due to the availability of other, easier and more sensitive methods - it is rarely used.

It involves placing the stethoscope over the artery just behind the cuff and listening to the sounds accompanying the drop in blood pressure.

Ultrasonic Doppler

This method evaluates blood flow as a change in the frequency of reflected sounds due to the movement of red blood cells as they move.

This measurement is usually performed on forelimb or the tail animal, however, it can also be performed on hind limbs.

As a rule, however, calm cats most tolerate the presence of a tightening cuff on the front paw, and thus - the examination is easier and faster.

Although this technique only gives us a systolic blood pressure value, it is preferred method for cats.

The absence of diastolic blood pressure values ​​is in most cases of no clinical significance, and the sensitivity of the Doppler blood flow method provides great diagnostic value.

In the video below you can see how systolic pressure is measured with ultrasonic doppler

Systolic Blood Pressure with a CAT + Doppler
Watch this video on YouTube

Oscillometry

Devices using this technique detect pressure fluctuations due to the cuff compressing the artery.

Until recently, traditional techniques of oscillometric pressure measurement in cats were considered less reliable and were characterized by low accuracy, which forced the necessity to increase the number of measurements during one test and to average the obtained results.

The introduction of the latest high-resolution oscillometry techniques has minimized many of the problems associated with traditional methods.

When using oscillometry, we get the pressure value systolic, diastolic and average value.

With this method, the cuff is placed over the the base of the tail, because it is the easiest place to carry out the measurement and generating the least distortions (for example due to the movement of the animal).

For some cats, if they are calm and not very mobile, it is possible to place the sleeve over the front paw just below the elbow.

Photoplethysmographic methods

A device that measures arterial blood volume through weakening of infrared radiation.

How blood pressure is measured in the office?

Blood pressure measurement from the office

Regardless of the measurement method used, it is necessary to ensure optimal conditions for the test.

Cats are difficult patients, and in order for the obtained results to be of diagnostic value, they should be reproducible.

This is quite a challenge in the case of highly stressed, struggling and purring patients.

Therefore, great emphasis is placed on providing the most optimal environment for the measurement.

Minimizing external factors influencing the results, such as noise, rush, too many people, presence of other patients (including dogs!) basically increases reliability and accuracy the results obtained.

When examining feline patients, the following procedures are recommended:

  1. Providing a calm and quiet room (away from other animals), sharp, unpleasant odors, with as few accompanying staff as possible. The kitten can stay in its own carrier, on its blanket, I often encourage owners to use cat pheromones beforehand (Feliway).
  2. It is important acclimatization. Before starting the test, it is worth encouraging your cat to become familiar with its surroundings. The patient should spend in the office 10-15 minutes before the study begins, he should also have a chance to get acquainted with the environment and people in it. If he is stressed and afraid to go out of his lair by himself, do not force him out of it.
  3. If any other activities are performed with the patient during the visit (e.g. body temperature measurement, blood sampling for tests, etc.), always start with pressure measurement. Subsequent manipulations will surely upset the furry, which will result in overstated blood pressure measurements.
  4. Staff. Underestimated, but extremely stressful for our client, is the presence of other people in the office. It should measure a person participating in the acclimatization, and during the examination, the owner has a soothing effect on the examined patient. Too many strangers to your cat will only increase its stress.
  5. Taming an assertive patient. Only a gentle hold is allowed, without adding to the fear. If the kitten breaks more and more during restraint and becomes restless, stop testing for a moment and return to it when the cat's emotions have subsided a little. A good way is performing an examination on a cat in the carrier.
  6. Patient positioning. Ideally, the furry body should retain the same body position throughout the study. He should lie down in a position that is comfortable for him and stay as relaxed as possible. Side position should not be forced. Movement of the cat, twirling, tapping the paw (this is how some patients try to throw off the uncomfortable cuff) unnecessarily prolongs the examination and distorts its results.
  7. Selection of the cuff and measurement site. The correct cuff width is 30-40% the perimeter of the place on which it is put on (most often the front limb, tail base, sometimes the hind limb).
  8. Blood pressure measurement. Before taking the correct measurement, it is worth inflating the cuff a few times to get the cat used to the strange feeling of squeezing the paw or tail. Then register 5-7 repeatable measurements, separated from each other 30-second breaks (the first measurement is usually rejected) and calculate the arithmetic mean from them.
  9. The results, along with comments on the surroundings, the size of the cuff and its positioning and the position of the animal's body, are recorded on special forms.

As mentioned earlier, optimal blood pressure for a healthy cat is 120/80 mmHg.

When using the oscillating method, this value ranges from 123-125 / 86-88 mmHg, and for the Doppler method the maximum systolic pressure is 118-120 mmHg.

However, due to the severe stress in cats, in fact - in office conditions - these values ​​can be much higher, even up to 160-170 / 100 mmHg.

It happens that in very agitated healthy cats the pressure reaches a value 180/120 mmHg.

What is cat hypertension?

So when we are dealing with hypertension in cats?

When the systolic pressure exceeds 190 mmHg, a diastolic 120 mmHg.

In patients with the so-called. "Gray zone ", where the measurements of the order are obtained 160-190 / 100-120 mmHg you may see an increase in blood pressure if there are any accompanying symptoms.

If in doubt, perform a control pressure measurement 7-14 days after the visit.

Hypertension in cats

Hypertension results from increased cardiac output and / or increased vascular resistance.

What does it mean?

That the volume of blood pumped out by the heart in one minute and / or the resistance to circulating blood through the vascular walls is greater than under physiological conditions.

This puts the heart in front of the need to generate more work, and it activates certain compensation mechanisms aimed at limiting the harmful effects of such a state.

High blood pressure is most commonly found in older cats (about 10-15 years) and in patients suffering from chronic renal failure or hyperthyroidism.

As a rule, it appears secondary to the primary disease.

Therefore, we talk about hypertension in cats when blood pressure measurements show a constant increase in systolic pressure above the physiological norm.

It happens that in completely healthy cats blood pressure reaches values ​​exceeding physiological values, especially in these elderly patients.

However, it has not yet been explained why this is so

The fact is that arterial hypertension in cats can be both cause and effect the formation of many disease states.

Not recognized on time can much reduce the effectiveness of treatment the underlying disease and lead to irreversible organ changes.

The most common causes of hypertension in cats

Primary hypertension (i.e. hypertension for no apparent reason) is rare in cats.

In the vast majority of patients, it accompanies the underlying disease, which predisposes them to such a condition.

Most often it is:

  1. Overactive thyroid gland. One of the most common causes of hypertensive state in cats (as much as approx 87% cases). In its course, there is an increase in the contractility of the heart muscle and an increase in the stroke capacity of the heart, and thus - an increase in blood pressure.
  2. Kidney failure. The second (most common) cause of hypertension in cats, occurring in 61% patients. One of the most important mechanisms inducing the state of hypertension is the increase in vascular resistance, resulting from compensatory changes occurring in the kidneys (narrowing of blood vessels, water and sodium retention).
  3. Overactive adrenal cortex. In cats, it is relatively less common than in dogs. As a result of excessive secretion of glucocorticosteroids, there is an increased secretion of catecholamines, which in turn triggers the hormonal cascade. As a result, hypertension develops.

Other conditions where blood pressure increases in cats include:

  • diabetes,
  • acromegaly,
  • phaeochromocytoma.

As you can see, high blood pressure in your cat is not usually a condition that appears "out of nowhere ".

In a small percentage of our feline patients, it is indeed idiopathic and, after excluding possible systemic diseases, its primary background is found.

However, in most cats, hypertension usually accompanies other diseases.

It is extremely important that if any of the above diseases are diagnosed, an arterial blood pressure test is performed and the basic therapy is adequately supported.

This will not only contribute to better treatment effects, improve the cat's well-being, but also minimize the risk of developing serious organ complications.

Clinical consequences and symptoms of cat hypertension

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Progressive Chronic Kidney Disease

We already know that in the course of kidney failure, high blood pressure is frequent.

However, the opposite may also be the case.

As a result of the permanent increase in systolic pressure greater than 160 mmHg the glomeruli are damaged and the number of active nephrons is reduced.

It appears in the urine protein, and the blood level rises urea and creatinine.

Clinically, the cat shows symptoms increased thirst and polyuria.

As a result of increased renal parameters in a cat, it occurs decreased appetite, which accompanies apathy. They may appear vomiting in a cat.

Complications in the cardiovascular system.

In the course of persistent hypertension, it develops compensatory left ventricular hypertrophy.

The heart tries to adapt to the increased pressure by giving in hypertrophy, which, however, results in:

  • reduction in stroke volume,
  • possible heart rhythm disturbances,
  • decrease in heart performance.

The owner observes his cat:

  • apathy,
  • decrease in appetite,
  • fatigue,
  • shortness of breath or other symptoms of heart failure may appear.

Retinopathies

One of the earliest symptoms of hypertension and the most frequent reason for consultation.

Chronic hypertension can lead to eye damage - the following may be visible:

  • haemorrhages into the retina, vitreous humor, or the anterior chamber of the eye,
  • detachment and retinal atrophy,
  • swelling of the retina,
  • inflammation in the vicinity of blood vessels,
  • twisting the vessels of the retina,
  • glaucoma.

The symptom most frequently observed by the owner is sudden loss of vision (associated with hemorrhage and retinal detachment).

Neurological complications

When the body's autoregulatory mechanisms are unable to cope with the effects of chronically high blood pressure, it can happen cerebrovascular hemorrhage or swelling of the brain.

In such situations, neurological symptoms appear, such as:

  • head twist,
  • depression,
  • seizures,
  • pushing your head against obstacles, etc.

Such symptoms appear most often in cats with systolic blood pressure higher than 300 mmHg.

Long-term hypertension affects the condition of blood vessels, and while the larger - large and thick arteries - still somehow "cope " with it, the smallest ones - capillaries - are destroyed.

That is why the lesions most often affect organs supplied by an abundant network of capillaries:

  • kidneys,
  • eyes,
  • brain.

Indications for the study of pressure in cats

Arterial hypertension in cats and any clinical situations that accompany it constitute a kind of vicious pathophysiological circle.

The occurrence of one of these conditions may lead to the appearance of another, which in turn results in serious organ and / or systemic changes.

Therefore, blood pressure measurement should be a standard and widely available diagnostic method, applicable especially in patients predisposed to hypertension.

When do I recommend having a cat's blood pressure measured?

When is it worthwhile to measure your cat's blood pressure??

It is certainly best to diagnose hypertension before systemic symptoms develop, i.e. blood pressure control measurements should be performed in cats at risk:

  1. In all patients with systemic diseases, such as:
    • kidney failure,
    • overactive thyroid gland,
    • overactive adrenal cortex,
    • phaeochromocytoma,
    • diabetes,
    • heart diseases,
    • eye diseases:
      • severe visual impairment,
      • hemorrhage into the anterior chamber of the eye,
      • retinal detachment,
      • glaucoma.
  2. In older cats (over 10 years of age).
  3. In obese cats.
  4. Routine blood pressure testing should also be performed in patients who have the following clinical symptoms:
    • neurological symptoms:
      • seizures,
      • chills,
      • dizziness,
      • confusion,
      • nystagmus,
      • spinning in a circle,
      • pushing your head against obstacles,
    • strong weakness, significant decrease in the activity of the kitten,
    • nosebleed, very red and hot ears (for no apparent reason), haemorrhage, bleeding, blood in the urine, vascular bursting, and bleeding into the eye,
    • unnatural excitement, making strange noises indicating agitation,
    • shortness of breath, fatigue quickly.
  5. An indication for blood pressure measurement are also any surgical procedures performed under anesthesia. The monitoring consists in periodic (every few minutes) measuring the pressure and saving the obtained values.
Monitoring of blood pressure in a cat

Treatment of hypertension in cats

Whenever a cat hypertension is diagnosed, the cause of its occurrence should be determined.

If it is a systemic disease, treatment of cat hypertension it should run in two ways:

  1. Therapy of the underlying disease (e.g. overactive thyroid gland).
  2. Treatment of hypertension.

Blood pressure should be checked regularly, as often it will normalize after the underlying disease is under control.

In the event that it is impossible to identify the cause of hypertension, he is introduced symptomatic therapy.

When to treat a cat's hypertension?

  • Every cat has systolic pressure > 200 mmHg or diastolic > 120 mmHg, regardless of clinical symptoms.
  • In cats with blood pressure in excess of 160/100 mmHg, with irregularities (eg. changes in the retina, chronic kidney disease), which may be caused or exacerbated by persistent high blood pressure.
  • Controversies still concern the so-called. gray zone - i.e. cats with moderately elevated blood pressure (> 160/100 mmHg), but there are no clinical symptoms associated with systemic hypertension. Some doctors then initiate treatment, others not yet.
  • Cats without clinical signs and with mildly elevated blood pressure (120-160 / 80-100 mmHg) do not require treatment.

Drugs for hypertension in a cat

Pharmacological treatment of cat hypertension

The main goal of pharmacological treatment is to minimize the risk of organ complications, reduce the harmful effects of adaptive mechanisms and - if possible - to reverse the changes caused by hypertension.

The following groups of drugs are used in cats:

  • Angiotensin converting enzyme inhibitors (benazepril, enalapril). They cause peripheral vasodilation and increase the excretion of sodium and water from the body, thus reducing peripheral resistance.
  • Calcium antagonists (amlodipine) - they reduce total peripheral resistance and amlodipine is effective as a single agent in cats. It is the drug of choice for cats (with benazepril if they have kidney disease).
  • Beta blockers (atenolol). They intensify the blood pressure lowering effect by reducing the cardiac output and release renin. The use of atenolol is indicated in hyperthyroidism in cats and in hypertension of renal origin.
  • Aldosterone antagonists (spironolactone) - a potassium-sparing diuretic.
  • Alpha blockers (prazosin) - used to dilate peripheral vessels.
  • Thiazide diuretics (hydrochlorothiazide) - they reduce the cardiac output and vascular resistance. Often given as first-line drugs in humans, but can cause in animals severe reduction in potassium levels in the serum.
  • Loop diuretics (furosemide) - diuretics, they prevent the retention of water and sodium in the body. Furosemide is recommended for patients with impaired kidney function.

Treating a cat's hypertension is not the easiest thing to do.

Sometimes the appropriate effect is obtained only after determining the optimal dose or introducing new drugs.

Hypertension associated with kidney disease often requires lifelong medication, while hypertension associated with hyperthyroidism or hyperadrenocorticism may resolve within 1-3 months with effective causal treatment.

Be aware of the side effects of medications, especially diuretics.

It is possible dehydration, drop in blood pressure below physiological norms as well worsening of uremia.

In the case of long-term administration loop diuretics it may appear hypokalemia (drop in potassium levels), therefore all cats with chronic kidney disease should have their levels checked regularly potassium and creatinine in the serum.

Appropriate selection of drugs and careful dosing usually ensure that systolic blood pressure is achieved (and this is the value we strive for).

Control pressure measurements should be performed initially every few to several dozen days, and then (depending on the patient's condition) - every 1-3 months.

Diet of hypertension in the cat

For patients whose high blood pressure is mild () and no organ damage is found, enter a low sodium diet (There are specials in the market veterinary diets dedicated, among others, to patients with cardiological diseases.

In cats with chronic renal failure and hypertension, it is more important at the beginning to maintain the appropriate caloric content of the food.

Only after high blood pressure has been stabilized pharmacologically, they introduce food with a reduced sodium content.

In obese kittens, you should try to reduce body weight.

Prognosis

The prognosis for increased blood pressure in a cat is closely related to the severity of hypertension and the accompanying diseases:

  • At a pressure below 150/90 mmHg the risk of damage to internal organs is minimal, and no treatment is required. In the absence of accompanying diseases, control pressure measurements are performed every 3-6 months.
  • Pressure in the compartment 150-159 / 95-99 mmHg makes low risk damage to internal organs. In healthy cats, it is often explained by the so-called. "White coat effect ", especially if they are very nervous and the examination takes place under stressful conditions. If, on the other hand, your cat has associated kidney disease, appropriate treatment should be initiated and the blood pressure monitored so that the blood pressure is less than 160 mmHg.
  • At pressure values 160-179 / 100-119 mmHg occurs moderate risk damage to internal organs. Diagnose and treat the underlying disease, and introduce medications to lower blood pressure.
  • High probability damage to internal organs occurs at pressure values > 180/120 mmHg. Such patients should be monitored frequently and meticulously, and antihypertensive treatment is usually used for the rest of the patient's life.

Summary

High blood pressure in a cat can be a symptom of a serious illness

Hypertension is a fairly common clinical problem, found especially in older cats, but often underestimated.

Knowing the symptoms accompanying hypertension, its timely diagnosis and the introduction of appropriate treatment not only significantly improves the therapy of the primary disease, but also reduces the risk of organ complications.

Hopefully, after reading this article, you already know how to measure your cat's pressure, what are the most common causes of hypertension in cats, and how high blood pressure is treated.

If you want to learn more about the symptoms, prevention and food for cats with hypertension, now post a question under the article - I will answer as soon as possible.

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