Name two common cardiac diseases in dogs and the typical signs.

• A. Aortic stenosis and pulmonary hypertension; syncope and leg pain
• B. Myxomatous mitral valve disease (MVD) and dilated cardiomyopathy (DCM); signs include coughing, exercise intolerance, and dyspnea
• C. Hypertrophic cardiomyopathy and pericardial effusion; bright red mucous membranes
• D. Patent ductus arteriosus and tricuspid atresia; headaches

Answer: (B)

Understanding which canine heart diseases are most commonly seen and what signs they typically produce is key. Myxomatous mitral valve disease and dilated cardiomyopathy are two of the most frequent cardiac conditions in dogs. Myxomatous mitral valve disease is the most common heart disease overall and tends to affect smaller breeds; it causes mitral regurgitation that ultimately leads to left atrial enlargement and pulmonary congestion. As it progresses, you’ll often notice coughing, exercise intolerance, and shortness of breath due to fluid backing up into the lungs.

Dilated cardiomyopathy, more common in larger breeds, weakens the heart’s pumping action by dilating and thinning the ventricular walls. This reduced cardiac output and increased pressures produce exercise intolerance and dyspnea, with possible lethargy or other signs as congestive heart failure develops.

The other options involve diseases that are either less typical in dogs or present with signs that don’t align as cleanly with common canine heart failure (for example, hypertrophic cardiomyopathy is more typical in cats, pericardial effusion has different clues, and many congenital defects aren’t the main two offenders with those presenting signs).