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Mitral valve insufficiency is the most common heart disease in dogs. The course begins insidiously. Is usually chronic. Signs of disease can be determined by certain indicators, with dogs going through stages of disease. The ACVIM method and the CHIEF classification help to classify the severity of the disease. Experience has shown that small breeds of dogs are particularly often affected by mitral valve disease, but larger dogs can also suffer from heart failure. Therefore, the disease should not be excluded at all in non-risk groups.
Basically, the risk of mitral valve degeneration increases with the age of the animal, the severity and progression of the disease varies from dog to dog. In the early stages, heart disease is often not recognized – in some cases the signs are hardly noticeable or are not associated with a disease of the heart. In mild courses in the early stages, long phases without therapy are possible; severe courses require drug treatment. Appropriate therapies can significantly improve the quality of life of affected dogs.
Diagnosis and classification
Mitral valve disease in dogs may be present from birth or may be due to degenerative changes with age. This is true in two-thirds of cases. Furthermore, the cause of heart failure can be found in acute inflammation or coronary arteriosclerosis. An overly rich diet combined with little exercise can lead to this condition in some cases. The resulting reduced blood flow to the heart muscle can lead to enlargement of the left ventricle of the heart. This in turn can lead to a reduced closing ability of the mitral valve. The pumping capacity of the heart decreases. The organism of the animal is no longer properly supplied with blood. Ischemia of individual organs occurs. Thus leading to its malfunction.
Symptoms of mitral valve regurgitation
As mentioned earlier, there are no clear symptoms that immediately indicate the presence of heart disease. It is much more important to observe and document the dog's behavior. If abnormalities occur, they should be examined more closely. In most cases, the pet owner notices a reduced performance capacity of the dog. The animal is less agile and eager to move, shows accelerated breathing at rest, but especially under stress. Due to the previously described enlargement of the heart, there is a deficiency in the supply to the lungs. The dog coughs frequently; at first only during excitement and joy, in the later course also in the resting state. In most cases, this is followed by permanently disturbed breathing with shortness of breath and shortness of breath. In the last stage, the dog has difficulty breathing while lying down. In addition, abdominal dropsy. Short phases of unconsciousness. The pet owner notices a significant weight loss in his dog. Food is refused and the animal makes an overall weak impression.
Heart failure: diagnosis of the disease
Heart failure: diagnosis of the disease | Covetrus Blog © didesign | Fotolia
There are several testing options available to detect cardiac disease in animals. With their help, cause. The degree of severity can be determined precisely in most cases.
The electrocardiogram records even the smallest cardiac arrhythmias. If no abnormality is detected for several minutes during the ECG, but the symptoms indicate the presence of heart failure, a long-term ECG can be performed. This is fixed with a special bandage so that the dog cannot remove it by itself.
The cardiopulmonary x-ray not only gives you, the veterinarian, information about the size and shape of the heart, but can also reveal pulmonary edema, for example. If the pet owner reports mainly breathing problems of the dog, extracardiac triggers of the breathing problems in the lungs can also be determined with the cardiopulmonary X-ray.
The ultrasound examination, echocardiography, very accurately records the internal structures of the heart. With the help of this examination procedure, congenital heart defects can be easily detected. By injecting a contrast medium, cardiomyopathy or fluid accumulation in the pericardium can be diagnosed or excluded. The functional capability of the heart valves can also be assessed in more detail using this method. Mitral endocardiosis is a thickening of the heart valves between the left main chamber and the left atrium. The echocardiography supports, in the presence of this clinical picture, in the coordination of the therapy as well as in the assessment of the prognosis.
Another diagnostic procedure is blood sampling to detect cardiac biomarkers. NT-proBNP is a stable metabolite that is detectable in the blood during cardiac stress. The accuracy of this examination to diagnose the severity and course of the disease is considered relatively imprecise and is currently being tested in an ongoing study called HAMLET.
Classification systems
The ACTVIM classification makes a clear distinction between symptomatic and asymptomatic patients and, like the CHIEF classification, refers to risk groups. The advantages of these two classifications are combined in the Dog Echocardiography Progression Protocol, the DEPP classification. This classification establishes seven stages for determining health status. In this examination scheme, the owner of the dog is first asked about the symptoms. The next step is to listen to the animal for murmurs. This is followed by examinations with X-ray and ECG. The combination of these individual factors gives the overall condition of the animal and therefore the stage the dog is in. Stages A, B1, B2, C1, C2, C3 and D are distinguished.
In stage A, no conspicuous heart murmurs are heard. X-ray and ECG show no findings. The dog belongs nevertheless, due to its anatomical conditions and/or because of its age or its race to a risk group. No noticeable symptoms are present. Further careful observation of the general condition is advisable. The dog is healthy.
At stage B1, auscultation reveals a heart murmur of 1-2/6. Mitral regurgitation is detected on X-ray. There are no signs of volume overload. The Vertebal Heart Score, which determines the size of the heart by X-ray, is normal. Echocardiography reveals a Cornell index of In stage B2, the patient shows heart murmurs of 2/6. X-ray and ECG show a clear insufficiency with compensation. The VHS is elevated, the myocardium is enlarged. The LA/AO ratio is greater than or equal to 1.6. The diastolic value of the Cornell index in the left ventricle is greater than or equal to 1.7. The dog coughs occasionally, has no respiratory restrictions, but shows mild performance insufficiency.
In the course of stages C1 to D, there is a marked deterioration in the general condition of the patient. In stage D, there are significant cardiac-. Lung sounds can be heard. X-ray shows pulmonary edema, thoracic effusion, and possibly water retention in the abdomen. The dog faints again and again, the skin shows clear signs of reduced blood supply by a blue-red discoloration. In addition, the dog can hardly breathe when lying down. Orthopnea is present.