Name two common canine cardiac diseases seen in older dogs and a key clinical distinction between them?

• A. Degenerative mitral valve disease (MVD) with a left apical systolic murmur and dilated cardiomyopathy (DCM) with reduced systolic function; MVD murmur, DCM may show tachyarrhythmias or S3; echo shows dilated ventricles.
• B. MVD and DCM both present with loud diastolic murmurs.
• C. MVD is primarily a disease of the aorta; DCM is a disease of the pericardium.
• D. MVD presents with clear lungs; DCM presents with normal echocardiography.

Answer: (A)

Two common cardiac diseases seen in older dogs are degenerative mitral valve disease and dilated cardiomyopathy. The key distinction lies in what each disease does to the heart and how it presents on exam and imaging.

Degenerative mitral valve disease is a valvular problem that leads to mitral regurgitation. This typically produces a left apical systolic murmur from the regurgitant jet. The heart can become volume overloaded, and the murmur’s timing and location on auscultation are the telltale clue.

Dilated cardiomyopathy, on the other hand, is a primary disease of the myocardium causing dilation of the ventricles with reduced systolic function. You may hear tachyarrhythmias or an S3, and echocardiography shows dilated chambers with decreased pumping efficiency.

So, the best distinction is the murmur from a mitral valve problem versus the reduced systolic function and dilated ventricles seen with DCM, often accompanied by arrhythmias or a soft S3.