Arterial hypertension in cats is a persistent increase in systemic arterial pressure, which has a detrimental effect on the walls of both large vessels and the walls of the vessels of the microvasculature. The range of normal systolic blood pressure in cats is 115-160 mm. rt. Art.
The result of tonometry is affected by: the type of recording device, the size of the cuff, the behavior of the animal (in a state of stress, the indicators may be falsely high).
Today, tonometry, like thermometry, auscultation and palpation, is an integral part of the examination of an animal over the age of 7 years. This makes it possible to detect hypertension early stages, to prevent the development of irreversible processes in the body of the animal. We can observe hypertension in animals with kidney disease, cardiomyopathies, endocrine disorders and changes from nervous system, as well as some other pathological conditions.
Causes of Hypertension in Cats
1. Hypertension "at the sight of a white coat" (an increase in blood pressure under stress. During tonometry, cats in an excited state may have falsely high blood pressure readings.). It is not a pathology.
2. Secondary hypertension develops against the background of systemic diseases.
There are many reasons leading to an increase in blood pressure in cats, for example, with such a pathological process, chronic renal failure, hyperthyroidism, Cushing's syndrome, diabetes are also registered against the background of acromegaly, polycythemia, pheochromocytoma.
3. Idiopathic (primary, essential) is not associated with a systemic disease, characterized by an increase in peripheral vascular resistance and endothelial dysfunction.
In animals, hypertension in most cases is secondary!
Symptoms of hypertension in cats
Persistent systemic hypertension in cats in most cases is a symptom of the underlying disease, but in itself entails the development of pathological processes in target organs.
These organs include: kidneys, visual apparatus, heart, nervous system.
The main symptoms of kidney damage - note progressive dysfunction associated with a steady increase in pressure glomerular filtration and microalbuminuria. High blood pressure is recorded at any stage of kidney disease.
As a result of hypertension, cardiac activity also suffers. Auscultation of these cats reveals a systolic murmur, a galloping rhythm, and echocardiography often reveals moderate left ventricular hypertrophy and diastolic dysfunction. During an electrocardiographic (ECG) study, ventricular and supraventricular arrhythmias, expansion of the atrial and ventricular complex, and conduction disturbances can be detected.
Against the background of high blood pressure, eye pathologies such as retinopathy and choroidopathy can develop, sometimes leading to visual impairment and acute blindness.
Neurological symptoms are dysfunction forebrain And vestibular apparatus. Damage to the forebrain is manifested by convulsions, a change in the mental state. The violation of the vestibular apparatus is evidenced by the tilt of the head, abnormal nystagmus, vestibular ataxia.
Also, neurological signs include: blindness, weakness, ataxia, tremor, decerebrate posture, episodic paraparesis.
In chronic hypertension, hypertrophy and hyperplasia of the smooth muscles of cerebral vessels with chronic vasoconstriction are noted. Such vascular degeneration is a predisposing factor to the appearance of microscopic hemorrhages. Cases of multiple arteriosclerosis with hemorrhage in cats with spontaneous hypertension have been reported in the veterinary literature.
Diagnosis of hypertension in cats
Diagnosing the causes of feline hypertension will include:
Routine tests:
1. Blood tests (clinical and biochemical blood tests)
2. Blood test for T4
3. Urinalysis with the ratio of protein and creatinine
4. Tonometry
5. Ophthalmoscopy
Additional diagnostics may also be required, such as:
6. Ultrasound survey of the abdominal cavity
7. Eye ultrasound
8. Cardiological examination (ECHOCG, ECG)
How is tonometry performed in cats?
There are several ways to measure blood pressure in animals.
The most common and reliable is the indirect oscillometric method. Medical tonometers are not suitable for measuring blood pressure in animals, so our clinics are equipped with special electronic veterinary tonometers "Pet Map", which are convenient in veterinary practice.
To conduct tonometry, the cuff of the device is applied to the animal in a calm environment in the area of the forearm, hock joint, lower leg, or at the base of the tail. Air is pumped into the cuff and fluctuations are measured as blood passes through the clamped section of the artery. To obtain the most reliable results, several measurements are taken. This procedure takes only a couple of minutes and, as a rule, does not cause any discomfort to the animal.
What is included in an eye examination?
When cat owners come to the clinic with complaints of poor eyesight, loss of vision, disorientation in space, hemorrhage in the retina, anterior chamber of the eye, or vitreous body, the veterinarian will definitely check the pupillary reactions, the reaction to light, the reaction to the threat, and will conduct an ophthalmoscopy. ultrasound eyeball carried out with extensive hemorrhage into the vitreous body, with cataracts and some other eye pathologies.
Indications for MRI/CT
If in persistent hypertension prevail neurological symptoms, after a series of studies, the veterinarian will refer your pet for additional diagnostics - computed tomography(CT) or magnetic resonance imaging (MRI).
These non-invasive methods will allow you to get a detailed image of the brain of good quality and detect signs of pathologies at different stages. They help to assess the condition of the smooth muscles of the cerebral vessels, detect aneurysm, neoplasm, and also confirm or refute some other pathologies of the nervous system.
Treatment of hypertension in cats
The first task of the attending veterinarian is to find the cause of hypertension. Early diagnosis and treatment will help to avoid the negative consequences of the disease. By treating the underlying cause with medication, hypertension can sometimes be completely cured. Symptomatic therapy is aimed at reducing systemic arterial pressure and preventing damage to the microvasculature of target organs, and improving blood circulation in them.
Prognosis for hypertension in cats
Forecast depends on reversibility primary disease, degree of target organ damage, response to antihypertensive therapy.
Our smaller brothers get sick in the same way as people. However, there are procedures that the owners neglect - tonometry or measuring the level of blood pressure (abbr. - blood pressure).
The concept of blood pressure, the rules for its measurement, normal indicators
Arterial pressure is calculated in mm Hg. (millimeters of mercury) and consists of two digits separated by a fraction. The first number is an indicator of the level of pressure with which blood presses on the walls of blood vessels at the moment when the heart makes a contraction. This state is called systole, and the pressure is called systolic. The second indicator is the level of blood pressure in the vessels at the moment cardiac relaxation or diastole. The indicator is called diastolic. The level of the general indicator of blood pressure directly depends on the state of the walls of blood vessels, their physiological resistance, as well as on the frequency of the heart.
A normal blood pressure indicator for a cat is: 120±16/80±14, i.e. on average, the level of 120/80 is considered the norm, as in humans.
Ways to measure blood pressure
Most often, the measurement of pressure in a cat is carried out using an oscillometric method using a conventional veterinary or digital tonometer. This is the safest and most accurate method for determining the state of blood pressure.
A special tonometer cuff is put on the paw or on the tail (depending on the condition of the animal and its size), which is connected to a special digital unit and a compressor or bulb to pump air. The pulse oscillation enters the digital unit and at the end a ready-made pressure value (systolic and diastolic) is issued.
Measurements are carried out several times, because. during the procedure, it is sometimes very difficult to achieve calmness of the animal, and increased mobility and anxiety are necessarily reflected in the final results.
The direct (invasive) method by catheterization of a peripheral artery is used extremely rarely, although it is considered the "gold standard". The method requires invasiveness (introduction into body tissues) and additional sedation of the animal (introduction into a drowsy state to reduce physical activity).
Dopplerographic, ultrasonic and photoplethysmographic methods can only be used with the appropriate technical equipment of veterinary clinics, therefore they are used infrequently. Also, these procedures have their cost.
Why should a cat measure blood pressure?
Most often, pressure is measured during or after operations, so as not to miss a critical drop in its level against the background of hidden internal bleeding (hypotension).
At routine appointments, it is important to measure blood pressure in order to determine in time such a condition as arterial hypertension(persistently maintained high blood pressure), which accompanies many pathological conditions body (heart failure, pathology of the kidneys and / or endocrine system, etc.).
In order not to miss hypertension, it is recommended to regularly measure the pressure of Murkams, whose age is older than 5-7 years - at least once a year, older than 10 years - once every six months. This is a mandatory frequency. This is especially true for individuals whose behavior attracts attention as unusual.
Elevated blood pressure in cats
Hypertension can be primary or secondary. Primary is considered when, in addition to a persistent increase in blood pressure, there are no more accompanying symptoms(idiopathic or unexplained). Secondary hypertension is an increase in blood pressure due to any other disease. The most classic version.
- With persistent averages up to 150 / 95-110, the cat is observed, in the absence of symptoms, treatment is not yet prescribed.
- Scores above 160/120 are direct reading to conduct appropriate therapy in order to avoid disruption of the work of individual organs and systems.
- A level above 180/120 is a reason to start immediate antihypertensive care.
Causes
- disorders in the work of the heart and the entire cardiovascular system;
- Cushing's syndrome (excessive production of steroid hormones by the adrenal glands);
- violations of the kidneys (especially in renal failure);
- endocrine pathologies (for example, diabetes mellitus);
- hyperthyroidism (increased production of hormones thyroid gland).
Manifestation
Most often it is asymptomatic. Over time appears:
- unsteady gait (cat as if drunk);
- frequent, prolonged and unusual meowing during the day;
- pupils may be dilated or hemorrhages may be noticeable;
- vision may deteriorate;
- coma, drowsiness, and during the period of wakefulness it seems that the animal does not understand what is happening around;
- shortness of breath (frequent, shallow (shallow) breathing);
- swelling on the paws;
- nose bleed;
- occasionally, seizures may occur.
How can I help you
Treatment is prescribed only by a veterinarian on the basis of an examination and collection of information, interviewing the owner of a mustachioed patient. Therapy is carried out in two parallel or successive stages - the underlying disease is treated and the level of blood pressure is normalized. In the process of treatment, the work of the renal system and eyes is necessarily controlled. Often, the elimination of the underlying disease leads to the normalization of blood pressure and the need for antihypertensive therapy disappears. The duration of the treatment course is determined strictly by a veterinarian. Often the intake of antihypertensive drugs remains on an ongoing basis.
- amlodipine(90-180 rubles, depending on the number of tablets in the package): inside from 0.5 to 1.25 mg / animal or with 0.2 mg / kg once a day or every 48 hours (two days). It is desirable to divide the tablet with a special tablet knife to reduce the risks of dosage violations. It is not addictive, the effectiveness of the action does not decrease from long-term use.
- enalapril, benazepril(65-300 rubles, depending on the manufacturer) : inside 0.25-0.5 mg/kg of animal weight once a day. Often used in combinations at a dosage of 1.25-1.5 mg/animal during the day. In very severe cases, the dose can be doubled, and after stabilization of the condition, return to the usual level.
- lisinopril(within 120-150 rubles/pack of 30 tablets): the initial maintenance dose is 0.125 mg/kg of body weight, the maximum allowable dose during the day is 0.5 mg/kg. Mandatory monitoring of kidney function. The course lasts 1-2 months, then you need a replacement for those drugs that can be taken for a long time.
- sodium nitroprusside: for emergency relief of hypertensive crisis. The dosage is determined only by a specialist and is administered only in a hospital! Dose: 1.5-5 mcg/kg body weight at a rate of 1 minute. Strict monitoring of the condition of the animal is shown, tk. a sharp drop in pressure can lead to disruption of the brain (ischemia).
In the presence of edema, diuretics are prescribed:
- furosemide(about 30 rubles / pack. 10 ampoules): 0.5-1 mg / kg per day orally or intramuscularly (in injections it works faster). The duration of application is determined by the veterinarian based on the general condition;
- torasemide(about 250 rubles / pack. 20 tablets): inside 0.05-0.1 mg / kg once a day. There are cats that are not sensitive to it - there are no patterns, just an individual reaction.
Low blood pressure in cats
Systemic hypotension in cats is extremely rare, and chronic hypotensive cats do not exist in nature at all. Basically, this condition is provoked by other primary pathologies. That is, as an independent persistent pathology, low pressure in mustachioed pets does not occur.
Causes
- intense bleeding and blood loss;
- against the background of exposure to anesthesia during operations;
- shock states of various origins;
- heart failure, etc.
Manifestation
- weakness;
- poorly palpable and slow pulse;
- there are cases of loss of consciousness;
- drowsiness and apathy;
- during surgery, the pressure drop is determined by monitors or pulsations of large veins;
- cold paws.
How can I help you
Help with low blood pressure in a cat should only be provided by a specialist. Depending on the cause, the following measures can be taken:
- antishock therapy;
- blood transfusion;
- replenishment of the volume of circulating plasma with the help of special plasma-substituting solutions;
- pacemaker injections.
Question answer
How to measure a cat's blood pressure at home?
Without a special blood pressure monitor for animals, it will not work to determine blood pressure readings at home. You can use the apparatus for a human, but the size of the cuff will not allow you to make accurate measurements. It can only be defined in in general terms whether the pet has high blood pressure or not. To do this, you need to put your fingers on the femoral artery: a strongly pronounced filling pulse with a clear pulse wave most likely indicates hypertension. It is better to visit a veterinarian to monitor the condition with a tonometer. A weak filling pulse with a barely pronounced pulse wave may indicate hypotension. You need to look for the cause of the decrease in blood pressure.
Can amlodipine be given to a cat? Dosage?
Yes, you can and should. One of the few antihypertensive drugs that is well tolerated and does not develop addiction. The dosage is prescribed by the veterinarian, depending on the condition of the animal at the time of contacting the clinic, age, size and on the basis of anamnesis. This is one of the first drugs that are prescribed to mustachioed pets after a diagnosis of hypertension. If there is no proper effect (which is very rare), amlodipine is replaced with another drug or combined with some other compatible antihypertensive agent.
The main signs of high blood pressure in a cat
If a cat / cat during the day long and drawn out meows for no particular reason, walks staggering, dilated pupils and heavy breathing, then by these signs it can be assumed that the cat has risen arterial pressure. It is better to play it safe and take it to the hospital for tonometry.
Normal blood pressure in a cat?
On average, as in humans - 120/80. However, the indicators are individual for each individual, so each animal will have its own norm. It is determined by regular pressure measurements over several days at the same time and deducing the average. Deviations are allowed up to 16 units in systolic pressure and up to 14 in diastolic. A systole value above 160 units is already considered critical and requires specialist veterinary care.
How and how to reduce the pressure of a cat at home?
It is strongly not recommended to make an independent correction of blood pressure indicators at home. An incorrectly selected dosage can provoke critical hypotension (an excessive drop in pressure to a critical level, when there may be a threat to life). Also, without identifying the cause of hypertension in a cat, treatment will be ineffective.
Can high blood pressure be prevented in cats?
Yes, you can. Starting from 5-7 years old, at least once a year or with strange behavior of the pet, conduct tonometry for control. From the age of 10 - twice a year. At an older age, each visit to the veterinarian should be accompanied by measurements of blood pressure. Monitor nutrition, do not give salty foods (for example, herring). Timely treat renal pathologies, if the situation allows.
How to urgently reduce the pressure of a cat?
Only a veterinary specialist can provide such assistance, because. a sharp drop in blood pressure can cause irreparable harm to the health of the pet, up to his death. At home, it is impossible to quickly and, most importantly, safely lower blood pressure!
Doctors call hypertension a “silent killer” because most people are asymptomatic, but statistics show that this pathology significantly increases the risk of diseases of the blood vessels of the brain, myocardial infarction and kidney failure. Unfortunately, the situation is quite different in veterinary medicine. In most animals, hypertension is diagnosed as a result of the onset of symptoms of severe KO lesions. This is largely due to the fact that veterinarians neglect to measure blood pressure (BP) in their patients during routine diagnostic examinations: at present, BP is determined mainly in cases of occurrence in animals clinical manifestations systemic hypertension.
MAIN PROVISIONS
> hypertension is usually diagnosed in cats when signs of end organ disease (TO) develop. The eyes are most often affected, which is accompanied by loss of vision in animals.
> Hypertension most often develops in aging cats; Animals with chronic renal failure are at the highest risk.
> Cats are easy to measure blood pressure (KD) non-invasive methods, but this can be difficult in animals in which hypertension develops from fear.
> Amlodipine, which blocks calcium channels, is currently the drug of choice for the treatment of hypertension in cats.
Clinical signs of hypertension
The clinical signs associated with hypertension that prompt cat owners to seek veterinary attention are most often eye lesions, but there are cases when increased BP is accompanied by severe disorders of the brain, heart and kidneys, sometimes there are bleeding in the nasal cavity (epistaxis).
Visual impairment in hypertension
Unfortunately, owners of hypertensive cats most often begin to pay attention to the health of their pets when they suddenly go blind. Other visual disturbances that owners notice in cats with high blood pressure include bleeding into the anterior chamber of the eye (hyphema) and dilated pupils (mydriasis). At ophthalmological examination in cats blinded by hypertension, hemorrhages are found in the anterior chamber of the eyes, vitreous body, retina and underlying tissues, as well as serous retinal detachment. In typical cases, the lesions are bilateral, although the pathological changes in one eye may be stronger than the other. Examples of such violations are shown in Figs. 1.
Figure 1. Lesions characteristic of hypertension in the eye of blinded cats,
A. Severe bumous retinal detachment.
b. Retinal detachment and numerous small retinal hemorrhages,
V. Hyphema.
Secondary changes that sometimes develop against the background of hypertension are glaucoma and retinal atrophy.
Mild changes are detected in cats only when examining the fundus before the loss of the cat's vision. At the same time, lesions such as small hemorrhages in the retina, its focal detachment and edema are detected. In addition, small, dark patches of focal degeneration may be seen in the retina. Such lesions are often found in the fundus tapetum, near the disc. optic nerve. Examples of these changes are shown in fig. 2.
Figure 2. Eye changes that can develop in hypertensive cats with vision. Photos published with the kind permission of Rebecca Elks.
A. Foci of hemorrhage in the retina.
b. Small areas of bullous retinal detachment.
V. Small areas of bullous detachment and foci of retinal degeneration.
Although visual changes in hypertensive cats are commonly described as "hypertensive retinopathy", this is actually pathological process covers the vascular layer to the greatest extent. For example, retinal detachment occurs when intraocular fluid is released from the terminal arterioles and capillaries of the iris and accumulates in the subretinal space. Degeneration of the retinal pigment epithelium occurs due to severe ischemia choroid. Optic nerve lesions are rarely reported in cats, possibly because such changes are masked by concomitant edema and hemorrhage. In addition, edema of the unmyelinated optic nerve, located in a secluded part of the eyeball, is quite difficult to detect in cats. Clinical features and pathophysiology associated with hypertension pathological changes The retina, iris, and optic nerve of cats are described in detail in a recently published review.
Neurological manifestations of hypertension
Hypertensive cats show the following neurological signs: weakness, ataxia, loss of orientation environment. Signs of vestibular dysfunction, neck flexion, paraparesis, stupor, convulsions and death. In cats with hypertension, neurological symptoms develop less often than visual disturbances: nevertheless, this is noted in at least a third of all cases. Meanwhile, it is very likely that neurological disorders often remain unrecognized for a number of reasons. Because of the variability in symptoms seen in cats with hypertension, hypertension cannot be diagnosed based on the neurological nature of the pathology. Many cats in this situation are euthanized before a definitive diagnosis can be made. In addition, in cats with severe ocular lesions, a proportion neurological disorders(e.g. depression) may be directly related to their blindness. The presence of mild neurological changes in hypertension may explain why many cat owners report an improvement in the clinical condition of their pets after starting their treatment with antihypertensive drugs, even if vision is not restored.
Cardiovascular manifestations of hypertension
Heart systolic murmurs and a gallop rhythm are often heard on auscultation of hypertensive cats. Diastolic heart murmurs and tachycardia are among other, less commonly recorded in this pathology, deviations from the cardiovascular system. arrhythmias and shortness of breath.
Meanwhile, heart murmurs and the other abnormalities mentioned are more frequently detected in aging cats, even those with normal KD. The latter circumstance does not allow us to assume hypertension based on the presence of such symptoms: in other words, to make such a diagnosis, it is necessary to measure BP.
Hypertensive cats rarely show signs of congestive heart failure. This happens when hypertension exacerbates some other existing cardiovascular disease in the animal, but is unlikely to be responsible for heart failure on its own. However, the suspicion of CVD in a cat does not eliminate the need to measure the animal's BP.
An x-ray examination in cats with hypertension establishes an increase in the heart, especially the left ventricle, and the presence of undulation of the thoracic aorta.
Echocardiographic changes most commonly seen in hypertensive cats include mild hypertrophy of the left ventricular wall and ventricular septum. However, it is noteworthy that heart sizes in many cats with systemic hypertension remain within the normal range. Differences in systemic echocardiographic parameters between normal and hypertensive cats of the same age are virtually minimal.
Diagnosis of hypertension
CD is determined by direct and indirect methods. Direct methods serve as the "gold standard". They are based on the puncture of an artery or the introduction of a catheter into an artery. Meanwhile, direct methods are unacceptable for routine measurement of BP in sick animals, due to difficulties in puncturing their arteries, increased BP as a result of pain reaction and stress in the animal during the procedure, and the risk of complications such as infection, vascular thrombosis, and hemorrhage. A method for measuring blood pressure with transponder sensors inserted into vessels on long time, but so far it has found application only in experimental studies.
Indirect methods are more convenient for measuring BP in diseased animals. Of these, in working with cats, the Doppler method and oscillometric methods are most often used. Korotkoff's auscultatory method, widely used in medicine, cannot be used to determine BP in cats due to the low amplitude of arterial murmurs. The choice of an indirect method for measuring blood in cats is not easy - each of them has its own advantages and disadvantages.
Oscillometric method
Oscillometric equipment detects changes in blood pressure in an air-filled cuff surrounding a peripheral artery. The oscillation amplitude varies depending on the BP and cuff pressure. The advantage of the method is the ability to determine both systolic and diastolic blood pressure.
However, the values of KD. corresponding to high amplitude oscillations are usually more reliable than systolic and diastolic BP values. Studies conducted on cats in a state of general anesthesia have shown that the oscillometric method gives underestimated values of BP (especially systolic), while it is increased. A fairly high rate of failed KD attempts has been reported in cats; these data confirm the results of studies on conscious cats in which average duration carrying out this procedure was excessively large.
More importantly, there are reports of that the results of oscillometric measurement of BP do not correlate well with indications of direct methods for determining BP in conscious cats and do not make it possible to diagnose cases of hypertopic eye damage. A number of factors can provide Negative influence on the results of measuring blood pressure in conscious animals, including physical activity and pulse rate, which are higher than in cats under general anesthesia.
Doppler method
This method is based on the measurement of an ultrasonic signal reflected by moving blood cells with a transducer.
The value of the CD is determined using a sigmomanometer, the cuff of which covers the limb of the animal proximal to the sensor. In one publication comparing direct and indirect methods for determining KD in animals under general anesthesia, it was reported that. that the Doppler method is more accurate than the oscillometric method, but in another experiment opposite results were obtained.
Dopplerists, however, prefer this method because it is more reliable for measuring BP in conscious cats and can identify animals with hypertonic ocular disease. The use of this method is limited by the inability to determine diastolic KD.
Nevertheless, the fluctuations of its consistently obtained readings are much smaller than those of other indirect methods for determining BP, these differences are most clearly manifested in the hypotensive state of animals.
Hypertension from fear
Whatever non-invasive method the veterinarian uses to measure BP, he must always take into account the existing phenomenon of hypertension from fright and take all possible measures to avoid this short-term increase in BP that occurs in animals during a visit veterinary clinic. The described phenomenon also manifests itself in people who are measured for BP, not only during an outpatient visit, but also during the provision of medical care. This can lead to an erroneous diagnosis of hypertension and subsequent treatment, which is not necessary. The possibility of developing the phenomenon of hypertension from fright in cats has been proven in experimental conditions. To measure blood pressure and heart rate, radio telemetry sensors were implanted in cats. Readings were taken under calm conditions and then during a visit to the veterinarian. It was found that the average systolic blood pressure in the latter case increased compared to the previous level, which was determined in a calm environment for 24 hours, by 18 mm Hg. Art. The nature and intensity of the manifestation of the phenomenon of hypertension from fright in different cats were not the same, and fluctuations in blood pressure during the period of short-term hypertension associated with it reached 75 mm Hg. Art. How pronounced the phenomenon of hypertension from fright would become could not be judged by changes in heart rate. The results of this and other studies have clearly shown the importance of giving cats the opportunity to adapt to the conditions in which they are supposed to be tested for KD.
Conditions for carrying out measurements of CD
KD can be measured on the front or hind limb, as well as on the tail. However, in order to obtain comparable results, this should always be done in the same place, since the results of determining the CD in different parts cat bodies can vary greatly. The width of the cuff should be approximately 40% of the circumference of the animal's limb. The use of a cuff that is too wide will result in low readings, and a cuff that is too narrow will result in high readings; however, the differences between the two are usually quite small.
What are the criteria for hypertension?
There is no consensus as to what level of BP should be considered sufficient in cats to diagnose hypertension. Very few studies have been conducted to establish the normal values of this indicator. Although those values of KD. which were determined by healthy cats different authors, differed significantly, however, the value of CD determined in different experiments in young healthy animals using implanted surgically radiotelemetric sensors, turned out to be the same. This indicates that the disagreement of different authors about the normal value of BP in cats is due to the unequal accuracy of their methods of indirect determination of BP or the phenomenon of hypertension from fright. A certain radiotelemetric level of CD in humans, cats and many other mammals turned out to be the same. Apparently, it corresponds to the value of BP, which achieves optimal blood supply to the brain and internal organs.
Mass examinations of people have shown that systolic and diastolic blood pressure has a pronounced long-term and etiological effect on the consequences of concomitant diseases. Therefore, knowledge of the value of "normal" and "hypertonic" BP is unnecessary - it is only important to maintain BP at the optimal level, which prevents undesirable consequences(For example, cardiovascular diseases). The optimal BP for many people is much lower than what is commonly considered "normal". For example, according to statistics, 25% of adults in developing countries world cd surpasses allowable rate, which dictates the need for their treatment with antihypertensive drugs. The situation is further complicated by that. What. as studies have shown, the optimal KD is not some kind of stable value, but depends on the clinical condition of the patient. For example, in people with kidney disease, the desired “optimal” BP should be significantly lower than for the world population as a whole (16). In cats, the only clinical complication of hypertension is eye damage, as evidenced by the results of numerous retrospective observations made in uncontrolled conditions. We diagnose systemic hypertension in this animal species when the systolic blood pressure exceeds 175 mmHg. Art. and there are eye lesions. If no change in the organs of vision is detected, then such a diagnosis can only be made by re-establishing an increased systolic blood pressure in the animal during its re-examination during next visit veterinary clinic. Once the diagnosis is made, treatment begins. Using these diagnostic criteria, it is possible to prevent the development of eye lesions in cats suffering from hypertension. However, it is not known if there is any further benefit from treating cats with lower BP. For example. 160-P5 mm Hg. Art.
Which cats belong to the group increased risk associated with the development of systemic hypertension?
In order to diagnose hypertension before the development of associated irreversible KO lesions and related symptoms, it is useful to have an understanding of Which cats are at the highest risk of systemic hypertension? Such patients should regularly measure BP as a preventive measure. Cats usually do not have primary hypertension - an increase in BP, as a rule, occurs against the background of other diseases (which caused the development of hypertension or co-existing), most often - chronic renal failure and hyperthyroidism. These questions are discussed in detail below. In addition, there are a number of less frequently diagnosed diseases in cats that can lead to systemic hypertension.
Chronic kidney failure
Chronic renal failure is the syndrome most commonly associated with severe hypertension in cats. In a mass screening of cats with hypertension accompanied by eye involvement, 44 out of 69 (64%) of the animals showed an elevated blood creatinine concentration.
HarrietM. Sim
Harriet M. Syme, BSc, BVetMed, PhD, MRCVS, Dipl ACVIM, Dipl ECVIM-CA
Lecturer in Domestic Animal Medicine, Royal Veterinary College, London, UK
Systemic hypertension in cats
Systemic hypertension refers to a chronic increase in systolic or diastolic blood pressure. Currently, this is a well-studied clinical phenomenon in domestic carnivores - it is especially often recorded in cats over the age of ten years. The diagnosis of systemic hypertension is usually made when the systolic and diastolic blood pressures of cats in calm state, reaches levels of 160 and 100 mm Hg. Art. respectively.
Blood pressure is the force with which blood presses against the walls of arteries. Its value depends on the heart rate and general peripheral resistance.
An increase in blood pressure can lead to an increase in HR or an increase in TPR. Thus, the prerequisites for increasing blood pressure are quite diverse.
Unlike humans, which develop primary systemic hypertension, in cats, it usually occurs as a complication of other diseases, most often accompanied by disorders functional state kidneys and endocrine system. Primary SH is rare in cats. However, since measuring blood pressure in small pets has become a routine procedure in veterinary practice, it has become clear that this problem is much more common in aging cats than in young animals. At the moment it is difficult to give exact data, but it can be assumed that SH affects 18-20% of the cat population. Just like humans, cats tend to have higher blood pressure with age.
The main cause of high blood pressure in cats is chronic kidney disease. Studies have shown that blood pressure is elevated in 20-60% of cats with kidney disease.
Primary hypertension
Pathologies of the adrenal glands Hyperadrenocorticism Pheochromocytoma Tumors of the adrenal glands producing aldosterontonia with a change in the degree of sodium and water retention in the body and with hyperactivity of the renin-angiotensin-aldosterone system, as evidenced by:
Hormonal disorders;
Results of histological and immunohistochemical studies of the kidneys of sick animals.
Studies show that systemic hypertension in cats often occurs as a complication of hyperthyroidism in cases where the diseased animal has not been treated or treatment has been ineffective. According to published data, 20 to 90% of cats with hyperthyroidism have SH. The actual prevalence of pathological SH in cats seems to be somewhat lower, as this animal species is highly sensitive to stress factors. SH in cats with hyperthyroidism is usually mild and reversible if the underlying endocrinopathy is treated promptly. SH arising from hyperthyroidism is a multifactorial disease. important role play an increase in heart rate caused by thyroid hormones, direct or indirect inotropic and chronotropic effects, excessive activation of the renin-angiotensin-aldosterone system due to stimulation of beta-juxta-glomerular receptors, which enhance the process of renin synthesis.
Other causes of SH in cats include diabetes mellitus and, less commonly, obesity, hyperadrenocorticism, pheochromocytoma, hyperaldosteronemia, side effects of drugs such as glucocorticoids, phenylpropanolamine, erythropoietin, and cyclosporine A. An excessively rapid intravenous infusion sodium chloride solution, as a result of which the transition of the subclinical form of systemic hypertension to clinical is accelerated or the blood pressure sharply increases, which was originally within upper bound physiological norm.
Effects of Sodium on Cat Health
It is well known that excessive sodium intake in certain animal species is a direct cause of SH, or at least a predisposing factor. A high salt diet used for a long time leads to an increase in blood pressure not only in rats with hypertension, but also in Wistar-Kyoto rats, whose blood pressure was within the physiological norm before the start of the experiment. Sodium content of 8% in terms of dry matter is considered to be elevated. For comparison: in industrial feed for cats that are currently being produced, the sodium content does not exceed 2%. Changes found in experimental rats were associated with the development of interstitial fibrous lesions of the kidneys and arteries of the left side of the heart. These changes occurred in parallel with increased expression in tissues of the gene encoding transforming growth factor beta-1. Moreover, in mice with renal failure resulting from the loss of part of the nephrons, it was found that excessive consumption sodium is accompanied by an increase in systemic blood pressure.
The genetic models of SH include Dahl rats, which exhibit increased sensitivity to salt. In these animals, when receiving food with a high content of sodium chloride, SH develops in combination with extremely intense fibrous and hypertrophic lesions of the arteries and myocardium of the left side of the heart.
People
It has been found that excessive salt intake can also negative impact on human health, including becoming a direct cause of high blood pressure. Increasing sodium chloride in the diet of people with salt sensitivity from 230 mg/day to 34.5 g/day for 15 days resulted in an increase in blood pressure, which in some cases increased by 30% above normal. Such a pathological high sensitivity Salt is considered a factor that increases the mortality of people, regardless of the base level of their blood pressure. Conversely, in a number of diseases accompanied by hypertension, limiting the intake of table salt often helps to lower blood pressure in the same way as special dietary supplements. medications. However, it should be borne in mind that the degree of influence of sodium chloride intake on blood pressure in different people highly variable, depending on a number of factors - genetic and age features, consumption levels of other electrolytes, and even concomitant drug treatment various drugs. genetic predisposition to hypersensitivity people to table salt seems to play the most important role, as evidenced by the results of a survey of Africans living in the Americas and patients with non-insulin-dependent diabetes mellitus.
healthy cats
There are far fewer observations regarding the effect of sodium intake on the development of SH in cats compared to published data in humans and rats. To the best of the knowledge of the authors of this chapter, there is no documented evidence of cat hypersensitivity to sodium chloride. On examination, it was found that cats with normal blood pressure who received more sodium than usual had an increase in water intake and the volume of urine produced. So, in ten young cats, a diet with a moderate content of sodium chloride, which they received for two weeks, did not cause changes in the value of systolic blood pressure, determined by the Doppler method: this indicator remained within the physiological norm, as in cats that were given a control diet. with normal salt content. In the same experiment, a high-sodium diet induced statistically significant increase only the level of water consumption and urine osmolality associated with a decrease in its relative density.
To draw a definitive conclusion about the effect of sodium on blood pressure in cats, it is necessary to conduct experiments to study the results of their consumption of increased amounts of table salt over a long period of time. Until such data are available, the National Research Council has recommended, based on the information already available, that up to 1.5% sodium on a dry matter basis of dry food at 4,000 kcal/kg be considered safe for healthy cats. This level of sodium intake is equivalent to 3.75 g Na/1000 kcal.
Cats with impaired renal function
Most of the complications of systemic hypertension occur when blood pressure rises above 180 mm Hg. cr.-, especially when it rises sharply. "
The kidneys are one of the main target organs for high blood pressure. If left untreated, systemic hypertension can lead to the development of nephroangiosclerotic lesions, which themselves can exacerbate hypertension that originally arose from other causes.
The heart is another important target organ for systemic hypertension. In an echocardiographic study conducted by specialists of the Toulouse National Veterinary School on 58 cats with hyperleanness, 85% of the animals showed abnormalities. In 59% of cases it was found
According to the available information, the blood pressure of healthy cats and cats suffering from chronic disease kidney disease, of moderate severity, is not affected by the level of sodium intake, since when it increases, animals begin to consume more water, and they produce urine in a larger volume; concentric hypertrophy of the wall of the left ventricle of the heart; in some cats this change was symmetrical, while in the rest it was asymmetrical. There was no correlation between the degree of parietal hypertrophy and blood pressure, as well as the age of the examined animals. Eccentric hypertrophy and hypertrophy of the cardiac septum were found in the region of the heart adjacent to bottom wall aorta in a smaller number of animals, however, both forms of changes were similar in incidence. Left atrial dilatation was associated with left ventricular remodeling in less than one third of cases. In cats, SH has also been found to be accompanied by changes in the proximal aorta.
Eye lesions are common in hypertensive animals. They are found in 50% of cats with hypertension and in 80% of cats in which high blood pressure is associated with kidney failure. In such cases, predominantly the vessels of the fundus change - this pathology is called hypertensive retinitis. It is manifested by disturbances in the course of retinal blood vessels, their expansion, local or diffuse preretinal and retinal hemorrhages, partial or generalized retinal detachment, which, if not treated promptly, can cause irreversible blindness. SH can also lead to hyphema, anterior uveitis, and even glaucoma in cats.
A sharp and significant increase in blood pressure in some cases leads to the development of brain lesions - this syndrome is called "hypertensive encephalopathy". Hypertensive encephalopathy presents with a range of clinical changes ranging from simple behavioral disturbances, ataxia, and spatial disorientation to more severe symptoms, including apathy, convulsions and coma. For reasons that are still unclear, hypertensive encephalopathy affects cats more often than dogs.
The first stage of diagnosis: making a preliminary diagnosis
SH should be suspected by veterinarians if a cat has a pathology that could be causing it. Other grounds for making such a preliminary diagnosis are usually:
a) the cat has one or more clinical or functional disorders, which may be accompanied by SH;
b) detection of an increase in the left half of the heart or remodeling of the left ventricle during an X-ray examination or ultrasound scan, respectively.
Systemic hypertension in cats can also be detected by routine blood pressure measurement. The basis for this is the establishment of an increase in blood pressure even in the absence of relevant anamnestic data and clinical signs of SH, as well as with negative results of radiographic and ultrasound examinations. However, the fact of elevated blood pressure in cats should be interpreted with great caution.
The second stage of diagnosis: confirmation of the diagnosis by measuring blood pressure
Doppler is now recommended by many researchers for measuring blood pressure in cats because it provides results quickly and is much easier to perform than oscillometry. In addition, there is a strong correlation between Doppler readings and direct catheterization, which is considered the gold standard for measuring blood pressure. The only drawback this method is the occurrence in some cases of difficulty in determining the level of diastolic blood pressure. However, experienced veterinarians can easily deal with such difficulties. A few basic rules should be followed to ensure that Doppler readings are as accurate and reproducible as possible, and to reduce animal anxiety, which in itself can cause hypertension, since overexcited cats are very often the cause of misdiagnosis.
Once a cat has been diagnosed with SH, a series of blood tests should be performed by the veterinarian to confirm or exclude the cat. primary causes high blood pressure, such as chronic renal failure and hyperthyroidism.
Most specific symptoms SH in the examined cats had retinal lesions, galloping heart rate, and polyuria-polydipsia, the only three clinical abnormalities that occurred with a higher statistically significant frequency in animals with SH compared to cats in which blood pressure remained normal.
