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Mitral valve insufficiency in dogs treatment. Mitral valve endocardiosis in dogs, treatment regimen

A healthy heart means a healthy body. This is an axiom in both medicine and veterinary medicine. Unfortunately, there are many dangerous pathologies of the cardiovascular system, which, if not detected in time, lead to severe forms of heart failure. The only problem is that animals are not constantly examined, and therefore the same endocardiosis of the mitral valve in dogs is often detected already at those stages when the pathological process has gone too far.

This is a chronic disease of the atrioventricular valve, characterized by the gradual and irreversible development of degenerative changes in it. Statistics show that this particular pathology is perhaps the most common cause, second only to various cases.

Stages of process development

For the first time, all stages of the process were summarized, systematized and studied by veterinarian Whitney, and this was back in 1974. There are four in total:

On first stage the left atrium and ventricle do not change in any way, but small “nodules” appear on the mitral valve itself, that is, places of degenerative tissue changes.

Second stage characterized by the merging of damage, and they also begin to involve the valve chords.

When the disease reaches 3 degrees, on the valve itself there are numerous growths in the form of plaques, the chords are thickened and noticeably “coarser” than normal. The thickness of the MC itself also increases significantly, and flexibility decreases. The basal portion of the valve is thickened and there may be areas of calcification (mineralization) and bleeding.

Process 4 degrees characterized by the fact that the valve tissues undergo rapid degradation, the shape of the latter is greatly distorted, and the edges are curled. In especially severe cases, the chords tear or completely lose elasticity, which allows the valve to dangle when the ventricle contracts, like an open window. At this stage, the valve may resemble an open parachute in the sky.

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Endocardiosis of the mitral valve alone occurs in 60% of cases, and with the participation of the mitral and tricuspid valves the process occurs in 30% of cases. The participation of only the mitral and aortic, only the tricuspid or aortic valves is a very rare phenomenon, as Buchanan wrote about in 1979. The older the dog, the faster the pathological process develops.

Clinical signs

What are the symptoms of mitral valve endocardiosis in dogs? As a rule, in young animals, signs of pathology increase slowly, since the body’s compensatory capabilities are still in effect. The first clinical signs are always vague heart murmurs. Gradually they become pansystolic, that is, they are heard with any contraction of the heart.

Very often, until middle age, the clinic does not appear at all. But subsequently, symptoms of acute heart failure quickly begin to increase, which is especially clearly confirmed by a constant cough due to a large amount of effusion (congestion in the pulmonary circulation). It is important not to miss this moment, since it is at this stage that treatment must be started urgently. Note that cough often appears only at night or after minor physical exertion (in the first stages, then it will become constant).

Subsequently, the disease quickly progresses to acute left-sided heart failure, the first sign of which will be constant shortness of breath. In the case when the tricuspid valve is also involved in the process, there are signs of right-sided heart failure, expressed in rapid exhaustion, severe shortness of breath, and ascites. When the situation becomes very difficult, fainting is possible.

Treatment

Typically, treatment of mitral valve endocardiosis in dogs is symptomatic and aimed at eliminating the most “gross” signs of heart failure. In the very early stages of the disease, that is, when heart murmurs are just beginning to appear, but there are no other clinical signs, there is no need to treat the animal, since there is no point in doing so. Even the theory of some veterinarians about limiting sodium intake from food has not found real confirmation in practice.

Endocardiosis is a heart valve disease common in small breed dogs. It is the latter who constitute the risk group for this disease. These breeds include Toy Terriers, Pekingese, Spitz, Chihuahuas, Poodles, Yorkshire Terriers, Spaniels, Dachshunds and French Bulldogs. Less commonly, this disease affects large dogs, mainly the terrier group, but in them it usually occurs less aggressively than in small dogs, and only in rare cases does it lead to serious consequences. With regard to dwarf breeds, the following correlation is observed: the smaller the weight of the dog breed, the more often representatives of this breed develop endocardiosis and the more severe this disease is in them.

General idea of the disease

Endocardiosis is a disease exclusively of the second half of a dog's life; it does not occur in young animals.

What is endocardiosis essentially? The heart is a biological pump, consisting of 4 chambers in dogs, as in humans, and providing continuous blood flow. Between its chambers there are valves that allow blood to flow in only one direction. During endocardiosis, these valves gradually become deformed, thicken, and no longer close tightly enough, beginning to let blood back through. As a result, the pressure inside the heart gradually increases. This leads to stagnation of blood and increased pressure in the vessels located near the heart.

In particular, changes in the valve located between the left ventricle and the left atrium lead to stagnation of blood in the veins of the lungs, which causes pulmonary edema. Pulmonary edema is a life-threatening condition and if not treated promptly, the dog can die. If there is pathology of the valve between the right ventricle and the right atrium, ascites occurs - a pathological accumulation of fluid in the abdominal cavity, which also requires treatment.

About 70% of cases of the disease affect only the valve located on the left side of the heart. Only 5% of cases of the disease affect only the right valve, another 25% of cases are associated with damage to both valves. Clinical manifestations of endocarditis are associated with this. The most frequently noted symptoms by dog owners are shortness of breath, rapid breathing, abdominal enlargement, increased fatigue, and fainting. All of these symptoms may appear at once, or one or more of them. The most common symptom, appearing earlier than others, is shortness of breath. You should pay close attention to your dog's breathing rate, which normally should not exceed 27 breaths per minute at rest. If you notice rapid breathing that is not associated with increased physical activity, you should immediately contact a veterinarian.

Initial development of the disease

But the onset of the disease significantly advances the appearance of its first symptoms. Cardiac ultrasound examinations of almost any older at-risk dog can detect signs of endocardial disease, but owners may not always notice the symptoms. As a rule, the first symptoms of endocardiosis appear after the age of 6 years, and the disease subsequently progresses with age.

The course of the disease has individual characteristics for each individual dog. Therefore, it is impossible to predict how the disease will manifest itself in the distant future, just as it is impossible to predict the speed of its development. Therefore, it is so important not only to identify the disease in a timely manner, but also to understand the characteristics of its course in a particular pet. The prescribed treatment is determined by the stage of the disease and the patient's condition.

Diagnosis of endocarditis includes a complex of different methods and approaches. First of all, the veterinarian personally examines the dog. Modern high-quality equipment cannot replace the hands, eyes, ears and head of a doctor. Important information can be obtained through a conversation with the owner, examination of the dog, auscultation - listening to the heart, its sounds, noises and wheezing, as well as palpation and percussion (that is, feeling with fingers and gently tapping them). Preliminary diagnosis is carried out at the stage of examining the dog, then the diagnosis is confirmed and individual characteristics of the course of the disease are identified using special diagnostic methods.

Of the diagnostic methods, echocardiography (ECHO), which is an ultrasound examination of the heart using a special Doppler ultrasound mode, plays a significant role. No other method is capable of providing such a quantity of data on the hemodynamic and anatomical individual characteristics of the heart.

ECG (electrocardiography), which is a technology for studying the electrical activity of the heart, is also widely used. Used to determine arrhythmias (heart rhythm disturbances) that may complicate the course of the underlying disease.

Cardiac pathology can trigger pathological processes and lead to diseases of other organs, primarily the liver, kidneys and brain. Due to the fact that endocardiosis is typical specifically for older animals, this category of patients often suffers from other diseases. Diagnosis of associated illnesses is sometimes carried out through a blood test.

Symptoms of respiratory diseases are often similar to symptoms of heart disease, in particular, signs of heart failure. For example, cough can be associated with both heart disease and respiratory tract diseases. The strength of the cough, its duration and other features can only suggest its cause, but it is impossible to make an accurate diagnosis without instrumental research. For this purpose, an X-ray method of examining the chest is used.

Actions to take if you have a risky breed

What to do if you become the owner of a cute dog of a “risky” breed? First of all, don't panic.

It is necessary to schedule the first visit to a veterinarian-cardiologist after the dog reaches 6 years of age, even if there are no pathologies in its condition. It is necessary to detect the disease as early as possible. It is likely that it will be too early to start treatment, but after the examination, the veterinarian will definitely inform you when exactly your pet’s heart will need to be checked again, so as not to “miss” the disease.

You should observe your dog's breathing, learning to count its frequency at rest. If the disease has been identified, such an extremely simple study will determine the moment when the pet’s condition worsens, after which a visit to the veterinarian will be necessary.

If your dog is already undergoing treatment, you must be extremely attentive to the recommendations of your veterinarian-cardiologist. In general, cooperation between the patient and the doctor plays a vital role and is a guarantee of effective treatment. Don't be afraid to ask if something is unclear. If for any reason the veterinarian is not trustworthy, you should not self-medicate, it is better to look for another veterinarian. But it should be noted that frequent changes of doctors worsen the effectiveness of treatment.

Many owners wonder: can the dog owner himself provoke the development of this disease? The answer here is negative, since endocardiosis is a genetically determined disease and does not depend in any way on the conditions in which the dog is kept. But a factor such as dog obesity can lead to aggravation of the disease. Therefore, maintaining the correct weight of the pet is an important responsibility of the owner.

To treat endocardiosis, there are currently no surgical methods to replace heart valves, so treatment is carried out exclusively by therapeutic methods and is aimed at eliminating the manifestations of heart failure, improving the quality and length of life. This disease remains incurable, but veterinary medicine can help the pet and make its life longer.

Predisposition

The highest predisposition to this disease and its earliest onset were noted in the Cavalier King Charles Spaniel breed. Presumably there is polygenic inheritance, which is influenced by age and gender. The risk group also includes the following breeds: miniature poodle, chihuahua, miniature schnauzer, fox terrier, Pomeranian, Pekingese, cocker spaniel, whippet, miniature pinscher. Of the larger breeds, endocarditis occurs in German shepherds, Dalmatians and Ridgebacks.

Pathophysiology

The development of endocardiosis in dogs involves the progression of 2 pathological processes: mitral regurgitation and valve degeneration.

Valvular degeneration consists of its abnormal contractions, leading to protrusion of the leaflets, which causes an increase in pressure on the leaflets directly and indirectly. Regurgitation leads to endothelial dysfunction by promoting fibroblast growth and causing subendothelial deposition of glycosaminoglycans followed by fibrosis. Over time, all these processes lead to disruption of the valve structure, as well as to an increase in regurgitation, while high pressure as a result of prolapse and changes in the structure of the leaflets cause rupture of the tendon strings (chordae), which aggravates regurgitation. At the final stage of the disease, the heart valve becomes a fibrous, narrowed valve, most often with rupture of the tendon strings.

The progression of valve damage leads to insufficiently tight closure of the valves and regurgitation, the development and severity of which is directly determined by the speed and degree of damage to the heart valves. Compensatory mechanisms lead to expansion of the ventricle and atrium, eccentric hypertrophy and an increase in the strength and frequency of heart contractions, as well as activation of neurohormonal systems. Ventricular dilatation at the same time increases regurgitation and leads to secondary valvular insufficiency.

As the disease progresses, compensation for regurgitation becomes impossible, leading to decreased cardiac output and increased venous pressure, as well as subsequent pulmonary edema or ascites. Pulmonary hypertension can result from left-sided heart disease.

Symptoms of canine endocardiosis

The most common symptoms of endocarditis in dogs are coughing (in some cases with white foam, which the dog swallows back), shortness of breath and exercise intolerance. Sometimes the dog becomes restless at night due to difficulty breathing when lying down. Fainting also occurs in some cases during physical activity or anxiety, during coughing (so-called cough fainting) or associated with supraventricular tachyarrhythmia.

An increase in coughing attacks is observed after drinking and physical activity. Sustained diffuse pulmonary edema develops, leading to moist rales. Over time, damage develops not only to the left, but also to the right side of the heart, this entails dilation of peripheral veins, ascites, and enlargement of the liver. Due to myocardial degeneration and atrial stretching, premature contraction of the atria often occurs - paroxysmal tachycardia.

The peculiarity of this disease is that it occurs without symptoms for the first few years.

Holosystolic murmur when listening to the heart is more pronounced in the upper left part (between the 4th and 6th left ribs) and is typical for those patients who have mitral regurgitation. This noise can travel in all directions. Mild regurgitation is often inaudible or is heard exclusively in early systole (in this case, a protosystolic murmur occurs).

Physical activity or emotional arousal often leads to an increase in the intensity of soft noises during mitral regurgitation. In further stages of the disease, a more pronounced murmur is noted, but in those dogs that have massive regurgitation and severe heart failure, the murmur is soft or completely inaudible. In some cases it resembles a musical tone.

Some animals with chronic mitral valve disease have a mid-late systolic clicking sound, with or without a murmur. A galloping sound is sometimes heard in the upper left side of the heart in dogs with advanced disease. Tricuspid regurgitation usually causes a holosystolic murmur, which is heard more clearly in the left upper part of the heart.

Pulsation of the jugular vein, vibration of the chest on the right in the area symmetrical to the location of the heart on the left, as well as features of the noise heard in the projection of the tricuspid valve help to differentiate the radiating noise of mitral regurgitation from the noise of tricuspid insufficiency in the right half of the chest.

Pulmonary sounds when listening can be both normal and pathological. Harsh, intense breathing and crepitus sounds heard at the end of inspiration (most clearly heard in the central fields) occur with pulmonary edema. Due to rapidly developing pulmonary edema, expiratory and inspiratory wheezing and shortness of breath develop.

Some dogs with mitral regurgitation have abnormal pulmonary sounds, which are caused largely not by heart failure itself, but by concomitant respiratory disease. Sinus tachycardia is common in dogs diagnosed with congestive heart failure. Dogs with chronic pulmonary disease often have sinus arrhythmia with a normal heart rate. Due to pleural effusion, lung sounds are weakened.

Clinical examination

During auscultation of a dog that is not currently showing any clinical signs, the following is revealed:

systolic click (at an early stage): high pitch, the presence of a sharp sound between the heart sounds S1 and S2; this sound is often mistaken for an additional heart tone (which causes the appearance of a gallop rhythm);
systolic apical murmur of the tricuspid or mitral valve;
early or late soft holosystolic murmur, corresponding to moderate or severe regurgitation.

A complete examination of the dog reveals:

loud heart murmur (levels 4-6/6);
weakened 1st tone;
ventricular arrhythmias, in particular atrial fibrillation, indicating a severe course of the disease and a poor prognosis;
weak and rare pulse observed in the femoral artery;
pallor of the mucous membranes;
tachypnea, orthopnea, respiratory distress;
wheezing, pulmonary edema;
pink foam in the nostrils, as well as in the nasopharynx in the presence of acute and severe pulmonary edema;
ascites, swelling of the neck veins (in case of right-sided heart failure).

Complicating factors

Canine endocardiosis is a slowly progressive disease, but certain factors can lead to acute symptoms in those dogs that have a compensated form of the disease. In particular, the severity of tachyarrhythmias may be strong enough to lead to decompensation of cardiac congestive failure. Paroxysmal atrial tachycardia, frequent atrial extrasystoles and atrial fibrillation can reduce the filling time of the cardiac ventricles, increase the need for oxygen in the heart muscle, and aggravate pulmonary edema. Ventricular tachyarrhythmias also occur, but they are less common.

Due to the sudden rupture of the chordae tendineae, which have undergone pathological changes, the volume of regurgitation quickly increases, which can lead to the rapid development of pulmonary edema - within a few hours in a completely devoid of any symptoms or a compensated dog. In addition, there are symptoms of heart failure. In some cases, a torn chorda tendineus is discovered by chance (on an echocardiogram), primarily when it is a chord of the 2nd or 3rd order.

Due to significant enlargement of the left atrium, compression of the main left bronchus sometimes occurs and a persistent cough is stimulated. This can occur even in the absence of heart failure. Also, a significant increase in the left or right atrium can lead to a complete or partial rupture of the wall, which leads to cardiac tamponade. This complication is most often observed in miniature poodles, dachshunds and cocker spaniels, especially in males.

Treatment and prognosis for endocardiosis

Drug treatment for canine endocardiosis is aimed at controlling the symptoms of congestive heart failure, supporting heart function, and correcting excessive neurohormonal activity that contributes to the development of the disease. Drugs that reduce the size of the left heart ventricle (diuretics) reduce the volume of regurgitation and the size of the fibrous mitral annulus. Drugs that promote arterial vasodilation increase cardiac activity and reduce the amount of regurgitation by reducing blood pressure.

The progression of the disease leads to the need for regular assessment of the dog’s condition, as well as periodic adjustments to treatment. In many dogs with severe mitral regurgitation, compensation is maintained for several years with proper treatment. Heart failure develops slowly in a significant proportion of affected dogs, while in other dogs there is severe, acute pulmonary edema.

Alternating episodes of decompensation in animals undergoing long-term treatment for heart failure can often be successfully reversed. When treating, it is necessary to take into account the clinical status of the animal and the factors that in a particular case complicate the course of the disease. Surgeries such as mitral annulus repair and other methods of mitral valve replacement and valve restoration may be used in some cases, but are not widely available.

About the author: Anna Aleksandrovna Maksimenkova

Practicing veterinarian in a private clinic. Directions: therapy, oncology, surgery. Read more about me in the "About Us" section.

The highest predisposition to this disease and its earliest onset were noted in the Cavalier King Charles Spaniel breed. Presumably there is polygenic inheritance, which is influenced by age and gender. The risk group also includes the following breeds: miniature poodle, chihuahua, miniature schnauzer, fox terrier, Pomeranian, Pekingese, cocker spaniel, whippet, miniature pinscher. Of the larger breeds, endocardiosis occurs in German shepherds, Dalmatians and Ridgebacks.

Endocardiosis is a disease exclusively of the second half of a dog's life; it does not occur in young animals.

About 70% of cases of the disease affect only the valve located on the left side of the heart. Only 5% of cases of the disease affect only the right valve, another 25% of cases are associated with damage to both valves. Clinical manifestations of endocardiosis are associated with this. The most frequently noted symptoms by dog owners are shortness of breath, rapid breathing, abdominal enlargement, increased fatigue, and fainting. All of these symptoms may appear at once, or one or more of them. The most common symptom, appearing earlier than others, is shortness of breath. You should pay close attention to your dog's breathing rate, which normally should not exceed 27 breaths per minute at rest. If you notice rapid breathing that is not associated with increased physical activity, you should immediately contact a veterinarian.

Symptoms of canine endocardiosis

The most common symptoms of endocardiosis in dogs are coughing (in some cases with white foam that the dog swallows back), shortness of breath and exercise intolerance. Sometimes the dog becomes restless at night due to difficulty breathing when lying down. Also, in some cases, fainting occurs during physical activity or excitement, when coughing (so-called cough fainting) or associated with supraventricular tachyarrhythmia.

The peculiarity of this disease is that it occurs without symptoms for the first few years.

Pulmonary sounds when listening can be both normal and pathological. Harsh, intense breathing and crepitation sounds heard at the end of inspiration (most clearly heard in the ventral fields) occur with pulmonary edema. Due to rapidly developing pulmonary edema, expiratory and inspiratory wheezing and shortness of breath develop.

Initial development of the disease

Diagnosis of endocardiosis includes a complex of different methods and approaches. First of all, the veterinarian personally examines the dog. Modern high-quality equipment cannot replace the hands, eyes, ears and head of a doctor. Important information can be obtained through a conversation with the owner, examination of the dog, auscultation - listening to the heart, its sounds, noises and wheezing, as well as palpation and percussion (that is, feeling with fingers and gently tapping them). Preliminary diagnosis is carried out at the stage of examining the dog, then the diagnosis is confirmed and individual characteristics of the course of the disease are identified using special diagnostic methods.

Of the diagnostic methods, echocardiography (ECHO), which is an ultrasound examination of the heart using a special Doppler mode, plays a significant role. No other method is capable of providing such a quantity of data on the hemodynamic and anatomical individual characteristics of the heart.

Actions to take if you have a risky breed

What to do if you become the owner of a cute dog of a “risky” breed? First of all, don't panic.

Chronic valvular degenerative disease (CDVD) is the most common cause of cardiac dysfunction in dogs. At least 75% of dogs with signs of congestive heart failure have mitral regurgitation caused by myxomatous degeneration of the mitral valve leaflets and chords (Chordae tendinea). In most dogs, the mitral valve is affected alone or in combination with the tricuspid valve.

Mitral valve insufficiency can also develop secondary to myocardial disease and other heart diseases, in particular due to volume overload of the left side of the heart. In these situations, valvular insufficiency is the result of the combined effect of chamber dilatation, mitral annulus enlargement, and ventricular and papillary muscle dysfunction (Philip R. Fox, David Sisson, N. Sydney Moȉse. Textbook of canine and feline cardiology: principles and clinical practice – 2nd ed. 1999).

In cats, unlike dogs, mitral regurgitation is more often associated with myocardial diseases and in the final stages of heart failure (according to one study), a clear relationship between mitral regurgitation and concomitant myocardial disease has not been proven (Tashjian RJ, Das KM, et al. Studies on cardiovascular disease in the cat. Ann NY Acad Sci 127:581, 1965). In cats, hypertrophic cardiomyopathy, mitral regurgitation, and fibrosis of the anterior mitral valve leaflet are observed as an inevitable result of dynamic left ventricular outflow tract (LVOT) obstruction. Mitral regurgitation tends to be common in cats with endomyocarditis and restrictive cardiomyopathy, in which the leaflets, chordae, and papillary muscles are destroyed and affected by fibrous plaques. Congenital mitral malformations usually lead to valvular stenosis, insufficiency of valve function, and dynamic obstruction of the left ventricular outflow tract.

The name Myxomatous Valvular Degeneration is a good description of the histological changes in the valve in dogs with chronic degenerative valvular disease. This pathology is also called endocardiosis and is divided into 4 stages.

Stage 1. Early changes. There are several isolated areas with small indurations or nodules in the area of the chordal attachment.

Stage 2. It is characterized by a large size of nodules and a large number of them with a tendency to merge. The valve chords are not yet affected and there is no mitral regurgitation at this stage.

Stage 3. Characterized by large nodules or “plaque-like” deformities resulting from further fusion of the lesions. The chordae at the points of attachment to the valve leaflets thicken. At this stage, the valve is significantly thickened and has a loss of elasticity. The basal part of the valve is affected, with areas of calcification and hemorrhage in the valve stroma. Valve insufficiency often occurs at this stage.

Stage 4. The valve flaps are shortened and significantly deformed. The free edges of the valves are curved upward. The chordae are thickened proximally and are often distended and sometimes torn. Valve insufficiency at this stage is always present and pronounced.

When detecting such changes in the mitral valve, it is important not to limit yourself to examining only the mitral valve. There are statistical data that damage to the mitral valve alone in chronic valve diseases occurs in 62% of cases, mitral and tricuspid - in 32.5%, mitral and aortic - in 2.5%, tricuspid - in 1.3% (Buchanan JW. Valvular disease (endocardiosis in dogs). Adv Vet Sci Comp Med 21:75, 1979).

With the age of the animal with endocardiosis, the risk of severity of the disease increases with a wider area of distribution. Stage 1 and stage 2 may be due to normal age-related changes unless it occurs at a very early age. However, in the early stages, lesions detected primarily in the proliferation of endothelium and underlying fibroelastic tissues in the valve contact areas cannot be reliably qualified as just normal age-related changes.

Other common morphologic changes found in dogs with mitral regurgitation include left atrial dilatation, mitral annulus dilatation, and eccentric left ventricular hypertrophy.

The etiology of CDVD is not clearly established. According to some researchers, the underlying pathological process is collagen degeneration (discollagenosis). The assumption of a genetic predisposition is based on the fact that CDVD is more common in dogs of chondrodystrophic breeds.

Other possible causes of chronic valvular pathologies in dogs include the following: stress, hypertension, hypoxia, past viral and bacterial infections and various endocrine pathologies. There is an opinion that there is a relationship between hyperadrenocorticism and myxomatous degeneration (Schneider P, Ernst E, Trautwein G, et al. Experimentelle durch ACTH und DOC induzierte herzklappenendocardiose. Endokrinologie 62:215, 1973).

Epidemiological data

According to various studies in different populations of dogs, CDVD was noted in 8.3-11-42%.

Age predisposition– in 10% of dogs aged 5 to 8 years, 20-25% in dogs aged 8 to 12 years and 30-35% in dogs over 13 years old.

Breed predisposition - in small breed dogs: toy, miniature poodle, miniature schnauzer, dachshund, Pomeranian, chihuahua, cocker spaniel, Pekingese, fox terrier, Boston terrier. In Cavalier King Charles Spaniels, mitral regurgitation is present in more than 40% of dogs 4 years of age and older, with chronic valvular disease being the dominant cause.

Sex predisposition. Males get sick more often than females (1.5-1.6/1.0).

Electrocardiography

Most often without pathological changes in dogs and cats with mitral regurgitation, before cardiomegaly has developed, recorded by radiography and/or echocardiography. Electrocardiography can be a more informative study if compared over time with recordings made earlier.

The P wave may be widened when the left atrium is dilated (p-mitrale, >0.04 sec in dogs and >0.03 sec in cats). Left ventricular enlargement suggests widening of the QRS complex (>0.06 sec in dogs and >0.04 sec in cats) or an increase in the amplitude of the R wave in II, III, AVF (>3.0 mV in dogs and >0.9 mV in cats). The position of the electrical axis is usually normal. The rhythm is usually sinus in cats and sinus arrhythmia or sinus tachycardia in dogs. Heart rate is variable and unchanged in dogs with mild to moderate left ventricular dilatation.

Radiography.

An earlier and more informative change on the x-ray is an enlargement of the left atrium. In the dorsoventral projection, there is an expansion of the left ear (the earliest sign); it looks like a small bulge of the left cranial part of the heart shadow (at 2-3 o’clock). A radiological sign of left ventricular enlargement is that the entire left border of the heart shadow becomes convex, and this may hide the enlargement of the left atrium. Over time, the enlarged silhouette of the heart begins to occupy most of the chest. The posterior border of the heart becomes more rounded and may shift to the right or left relative to the midline. This sometimes makes it difficult to differentiate left ventricular enlargement from biventricular enlargement. As the atrium dilates, the main bronchus shifts and assumes a more obtuse angle.

In the lateral projection, one can see that the expansion of the left atrium leads to a dorsal displacement of the trachea, reducing the angle between the trachea and the spine, until it disappears completely. When the enlarged left atrium displaces the main left bronchus dorsally, the latter is visualized dorsal to the right. Dilatation of the left atrium and left ventricle leads to protrusion of the caudal border of the cardiac shadow. The craniocaudal and dorsoventral size of the heart shadow increases. However, this does not show the share of participation in this expansion of the left and right ventricle. Widened sternal contact may characterize enlargement of both ventricles. Further dilatation of the left atrium combined with dilatation of the proximal parts of the pulmonary veins leads to the formation of a wedge-shaped compaction that continues into the diaphragmatic part of the lung field.

It should be especially emphasized that x-ray examination is a fairly sensitive clinical study of pulmonary hemodynamics. As left-sided heart failure progresses, high-quality radiographs show early changes in the pulmonary veins and pulmonary interstitium. As pulmonary venous pressure increases, the veins dilate and become more visible both centrally and at the periphery of the lung fields. The veins become denser and wider than the pulmonary arteries located parallel to them. At this stage, the transfer of fluid from the pulmonary capillaries to the interstitium increases. In the initial stages, this is not visualized radiographically, due to the fact that excess fluid inertia is drained by pulmonary lymph flow. A further increase in venous pressure leads to radiographically detectable interstitial edema. Fluid retention in the perivascular lymphatic ducts and interstitium results in loss of distinct pulmonary vascular margins. The accumulation of fluid in the walls of the bronchi and bronchioles causes peribronchial compactions. Further fluid retention leads to increased radiodensity of the lungs and loss of contrast between the parenchyma and bronchovascular structures. These changes are usually more pronounced in the hilar zone or in the right caudal lobes of the lung. In dogs, alveolar pulmonary edema is characterized by the appearance of vague “down-like” consolidations, air alveolograms and air bronchograms, developing first in the hilar region or in the right caudal lobe. In cats, the location of edema is more variable.

Echocardiography

Echocardiography as a method for diagnosing chronic heart failure is the main and expert method. None of the methods listed above can replace echocardiography.

Thickening of the valve leaflets is fairly easy to recognize on echocardiography in most dogs with chronic degenerative valvular disease. These changes are most clearly visible in the anterior (septal) leaflet of the mitral valve. With a high degree of damage or when the chords are ruptured, the movement of the valves becomes stronger and more chaotic. Along with this, prolapse of the mitral valve leaflets into the left atrium during the systole phase may be observed. Dilatation of the left ventricle is observed in different degrees depending on the severity of the disease. In most cases, there is progression of left atrium dilatation. The contractility fraction of the left ventricle increases with increasing mitral regurgitation, however, with the development of the disease and developing myocardial dysfunction, the contractility fraction may return to normal values and then decrease. Left ventricular end-systolic size and end-systolic volume may be one of the best indicators of myocardial function, since these measures always tend to increase with the development of myocardial failure. The location and extent of the regurgitant flow (as an earlier indicator of the extent of the disease) can be assessed using Doppler ultrasonography. For this purpose, color mapping is used. Color Doppler can provide good information about the extent of mitral and tricuspid regurgitation, but the extent of the disease is better assessed by the size of the left atrium and measurements of left ventricular function.

Treatment

Treatment of chronic heart failure in dogs with mitral valve endocardiosis should pursue the following goals: eliminating symptoms (dyspnea, cough, ascites, etc.), increasing life expectancy and protecting “target organs” (heart, lungs, brain, kidneys, etc.) .d.). The extent of treatment depends on the stage of the disease.

As part of the 4th Cardiological Conference (2010), the Cardiological Veterinary Society presented draft recommendations for the treatment of endocardiosis in dogs. The advantageous difference of the proposed project is that it takes into account not only the functional class, but also the index of objective changes. This provides a more differentiated approach when prescribing treatment.

The proposed indices mean:

A	The expansion of the left atrium is moderate. Slight dilatation of the left ventricle. Mitral regurgitation grades 1-2.2. Left ventricular contractility fraction 35%. Slight dilatation of the left atrium. The right ventricle is normal. There is no pulmonary hypertension. There is no congestion in the lungs on x-ray.
B	Significant expansion of the LP. LV expansion. Contractility fraction 45-55%. The dilatation of the pancreas is insignificant. LH initial. Stagnation in a small circle. Minor hepatomegaly.
C	Significant expansion of the left sections. Significant expansion of the right departments. Contractility fraction 45% Pulmonary hypertension. Threat of pulmonary edema. Stagnation in the larger circle.
D	Expansion of all cameras. Marked stagnation in the large circle. Cachexia. Low blood pressure. Azotemia. Hypoalbunemia.

	A	B	C	D
FC I	ACEI Amlodipine Training/Observation Or don't treat it.	ACEI Amlodipine BAB (tahi)	ACEI Amlodipine? Pimobendan or Digoxin Furo-/Tora+ Veroshpiron (elimination of stagnation)	-
FC II	ACEI Amlodipine BAB(tahi) Diuretics (small doses for a short time)	ACEI Amlodipine Furo-/Tora+	ACEI Amlodipine AD Pimobendan or Digoxin Furo-/Tora+ Veroshpiron (small doses)	-
FC III	Differential diagnosis	ACEI Amlodipine AD Pimobendan and/or Digoxin BAB? Furo-/Tora+ Veroshpiron (reduce after compensation)	ACEI Amlodipine? Pimobendan and/or Digoxin Furo-/Tora+ Veroshpiron Sildenafil	ACEI Pimobendan and Digoxin Torasemide+ Hypothiazide+ Veroshpiron Sildenafil
FC IV	Differential diagnosis	ACEI Pimobendan and/or Digoxin BAB? Furo-/Tora+ Veroshpiron (if there is no compensation - differential diagnosis)	ACEI Pimobendan and Digoxin Torasemide+Veroshniron Sildenafil Dobutamine Furosemide IV Nitrates Laparocentesis Amlodipine AD Antitussives Antibiotics	ACEI Pimobendan and Digoxin Torasemide+ Hypothiazide+ Veroshpiron Sildenafil Adjuvant therapy

Abbreviations: ACEIs – angiotensin-converting enzyme inhibitors. BAB - β-blockers, Tora - torasemide. Furo - Furosemide.

It is important to note that from the initial stages of the disease to decompensated conditions, it is necessary to use ACEIs (Angiotensin Converting Enzyme Inhibitors). Ramipril (Vasotope® Intervet/Schering-PloughAnimalHealth) is widely used in veterinary cardiology. The drug, according to the principles of evidence-based medicine, has an evidence index of “A”, which makes its use completely justified.

Left - Echocardiography of a dog with endocardiosis (induration, thickening and deformation of the mitral valve leaflets).
Right - Mitral regurgitation.

In city apartments, dog lovers are increasingly choosing representatives of miniature breeds. And rarely do the happy owners of a baby think about the diseases characteristic of this breed. Meanwhile, we can identify a whole group of diseases characteristic of small dogs. As a cardiologist, I would like to talk about a heart disease called Endocardiosis.

Endocardiosis is a disease of the heart valves that is common in small breed dogs. Most often, dogs in the so-called risk group suffer from this disease. These are Pekingese, Toy Terriers, Chihuahuas, Spitz, Yorkshire Terriers, Poodles, Dachshunds, Spaniels, Pugs, French Bulldogs. Damage to the valves is less common in large dogs, especially the terrier group, but, as a rule, the disease is not aggressive and rarely leads to serious consequences. As for dwarf breeds, there is a certain tendency: the lower the weight, the more common Endocardiosis is and, as a rule, it is more severe.

Endocardiosis is a disease of the second half of life and does not occur in young animals.

What is Endocardiosis? The heart is a kind of pump, consisting of 4 chambers, whose task is to ensure continuous blood flow. Valves are located between the chambers of the heart; their task is to allow blood to pass in only one direction. With endocardiosis, these valves gradually thicken and become deformed, stop closing tightly and begin to let blood pass in the opposite direction. The pressure in the chambers of the heart gradually increases. This automatically leads to increased pressure and stagnation in the upstream vessels. So, if the valve, which is located between the left atrium and the left ventricle, is changed, stagnation of blood develops in the pulmonary veins, which can lead to pulmonary edema. This is a life-threatening condition; if the animal is not given timely help, it may die. If there is pathology of the valve between the right atrium and the ventricle, ascites develops - accumulation of fluid in the abdominal cavity, this also requires treatment.

It has been noticed that in approximately 70% of cases, the valve located in the left side of the heart suffers. At 5% - the valve is on the right side. In 25%, both valves are affected. The clinical picture observed in Endocardiosis is also connected with this. Among the symptoms that the owner may notice, the most common are rapid breathing (shortness of breath), increased fatigue, an enlarged abdomen, and sometimes fainting. These signs may be present all together or separately. The most common symptom that develops earlier than others is shortness of breath. It is very important to pay attention to your dog’s breathing rate; normally, at rest, it does not exceed 27 per minute. If you notice rapid breathing in your pet, which is not associated with heavy physical activity, but appears after minor exertion or is observed at rest, you should immediately consult a veterinarian.

However, the disease begins to develop long before the first symptoms appear. In almost every dog from the risk group of the older age group, an ultrasound examination of the heart can reveal signs of Endocardiosis, but owners do not always note the symptoms of the disease. Typically, the first signs of Endocardiosis can be noticed after 6 years, and the disease progresses with age. Each dog has individual characteristics of the course of the disease. Despite the same physical and biological laws occurring in the body, it is impossible to predict in detail how the disease will behave in the long term and at what speed it will develop. Therefore, it is so important not only to detect the disease in a timely manner, but also to understand how it progresses in a given animal. Treatment is prescribed depending on the stage of the disease and the patient’s condition.

A combination of different methods and approaches is used to diagnose Endocardiosis. First of all, the doctor examines the animal. Not even the most modern device can replace the eyes, hands and head of a doctor. A lot of information can be gleaned from a conversation with the owner, examination, auscultation (listening to heart sounds, murmurs, wheezing), palpation and percussion (as in medical language palpating and gentle tapping with fingertips are called). A preliminary diagnosis is made already at the stage of examining the patient; further, special diagnostic methods can confirm the diagnosis and identify the features of the course.

First of all, we should mention Echocardiography (ECHOkg) - this is a study of the heart using ultrasound using a special Doppler mode. No other research method provides so much information about the anatomical and hemodynamic (hemodynamics - the movement of blood through the chambers of the heart and vessels) features of the heart.

In addition to Echocardiography, everyone knows such a research method as ECG (Electrocardiography). This is a way of recording the electrical activity of the heart. It is used to detect arrhythmia (heart rhythm disturbance) that may complicate the course of the underlying disease.

Heart pathology itself can trigger a cascade of pathological processes and cause diseases of other organs. Often such target organs are the kidneys, liver, and brain. In addition, Endocardiosis is more common in older animals; concomitant diseases are often detected in this category of patients. To diagnose concomitant pathologies, in some cases a blood test is required.

Respiratory tract diseases often have symptoms similar to heart failure. For example, a cough may be associated with both heart disease and respiratory tract pathology. Based on the strength, duration, and other features, the origin of the cough can be assumed, but it cannot be accurately diagnosed! To make a diagnosis in such cases, an X-ray examination of the chest is required.

What to do if you are the owner of a cute dog at risk? Don't panic! Knowledge is power!

The first visit to a cardiologist should be scheduled at age 6, even if you do not notice any abnormalities in your dog’s condition. Remember, it is necessary to identify the disease as early as possible! It may be too early to start treatment, but after the study, the doctor will definitely tell you when the next time it is necessary to check your friend’s heart, so as not to “miss” the disease.

Observe the animal's breathing. Learn to count your dog's resting breathing rate. If the disease has been identified, this very simple test will tell you when the animal's condition begins to deteriorate and you should make an unscheduled visit to the doctor.

If your animal is already receiving treatment, pay very close attention to all the recommendations of your veterinary cardiologist. Therapeutic cooperation between doctor and patient is very important; this is the key to good mutual understanding and successful treatment. Don’t be afraid to ask again if you don’t understand something. If for some reason you do not trust the doctor, do not self-medicate, look for another doctor. However, I would like to warn that changing clinics and doctors too frequently does not bring benefit to the patient or the desired effect.

Many owners ask: could they provoke the development of the disease? Endocardiosis is a genetically determined disease that does not depend on the conditions of keeping and feeding the animal. However, obesity can aggravate the disease. Maintaining a dog's normal weight is the most important responsibility of the owner!

Regarding the treatment of Endocardiosis: currently, the surgical method of replacing heart valves is not used in veterinary practice; treatment is carried out therapeutically. Treatment is aimed at eliminating the symptoms of heart failure, improving quality of life and increasing its duration. Of course, we cannot cure this disease, but we can help the animal and prolong its life!