Cardiac disease is a common condition in veterinary medicine and an important topic on the VTNE®. Veterinary technicians must recognize early indicators of heart disease and understand how common cardiac conditions present in dogs and cats.
The three most common diseases in both clinical practice and exam questions are myxomatous mitral valve degeneration (MMVD), dilated cardiomyopathy (DCM), and hypertrophic cardiomyopathy (HCM). Understanding these conditions helps technicians identify abnormal findings during physical examinations and assist with diagnostic testing and patient monitoring.
The Veterinary Technician’s Role in Identifying Cardiac Disease
Many patients with early heart disease initially appear healthy. Veterinary teams often detect abnormalities only during a physical examination or with a detailed history.
Veterinary technicians play a key role in identifying these subtle findings. Detecting abnormalities such as heart murmurs, abnormal pulse quality, or arrhythmias can prompt further diagnostic evaluation.
Recognizing subclinical cardiac disease allows the veterinary team to begin monitoring or treatment before patients progress to congestive heart failure (CHF).
Once CHF develops, animals commonly present with clinical signs such as coughing, exercise intolerance, lethargy, collapse, or respiratory distress.
Myxomatous Mitral Valve Degeneration (MMVD)
Myxomatous mitral valve degeneration is the most common cardiac disease in dogs, particularly in older small and medium-sized breeds.
This condition occurs when the mitral valve leaflets become thickened and distorted. As the valve degenerates, it fails to close properly during systole. This means blood leaks backward from the left ventricle into the left atrium, creating turbulent blood flow. This turbulence produces the characteristic heart murmur often detected during physical examination.
Over time, the condition can progress to left-sided congestive heart failure, resulting in pulmonary edema and respiratory distress.
Dilated Cardiomyopathy (DCM)
Dilated cardiomyopathy most commonly affects large and giant breed dogs, including Doberman pinschers, Great Danes, and Irish wolfhounds.
In DCM, the heart muscle becomes weakened and stretched, decreasing contractility. The ventricular chambers enlarge in an attempt to compensate for the decreased cardiac output. Because the dilated heart cannot effectively pump blood forward, fluid may accumulate within the lungs or body cavities. Arrhythmias are also common.
Some dogs with DCM may not have a heart murmur, which can make early detection challenging. Owners might report exercise intolerance, episodes of collapse, or weakness. Patients are sometimes first diagnosed only when they develop congestive heart failure with pulmonary edema, pleural effusion, or abdominal fluid accumulation.
Hypertrophic Cardiomyopathy (HCM)
Hypertrophic cardiomyopathy is the most common heart disease in cats.
In HCM, the walls of the left ventricle become abnormally thickened, reducing the chamber size and limiting proper filling during diastole. As a result, the heart pumps less blood to the body, which eventually backs up and dilates the left atrium. Cats with HCM may or may not have obvious abnormalities during auscultation. Some develop heart murmurs or gallop rhythms, while others show no detectable abnormalities on physical exams. Additionally, about 50% of murmurs noted in cats are non-pathologic (innocent murmurs), making their detection fairly non-specific for disease.
Cats with HCM can develop CHF (pulmonary edema and/or pleural effusion), fatal arrhythmias, or formation of blood clots within the left atrium.
One serious complication of feline HCM is arterial thromboembolism (ATE). In this condition, a blood clot forms within the dilated left atrium, travels through the bloodstream, and obstructs a major artery. The most common site of obstruction is the aortic trifurcation, producing an extremely painful condition commonly called a “saddle thrombus.”
Diagnostic Tests for Cardiac Disease
Several diagnostic tests help veterinarians evaluate cardiac disease in dogs and cats.
Thoracic radiographs provide information about heart size and shape. They can also reveal evidence of pulmonary edema or pleural effusion. The vertebral heart score, calculated on radiographs, objectively assesses heart enlargement.
Electrocardiography (ECG) evaluates the heart rhythm and identifies arrhythmias and abnormalities in the complex appearance.
Blood tests are available to screen for myocardial damage and identify patients in need of further workup.
Echocardiogram, an ultrasound of the heart done by a cardiologist, is considered the gold standard diagnostic test for cardiac disease. The veterinarian can visualize and measure heart chambers, valves, and blood flow in real time.
Elevating Patient Care through Cardiac Knowledge
Cardiac disease is a common and clinically important topic for veterinary technicians and VTNE® candidates.
Understanding the key features of myxomatous mitral valve degeneration, dilated cardiomyopathy, and hypertrophic cardiomyopathy allows technicians to recognize concerns in both the history and examinations and best assist with appropriate diagnostic testing.
These skills improve both VTNE® performance and patient care in everyday veterinary practice.
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