Murmur in a kitten: when to perform an echocardiogram?

Question

9-week-old domestic shorthair kitten, active, growing well, with pink mucous membranes. You hear a grade 2/6 systolic murmur in the left parasternal area. There is no thrill, no arrhythmia and no respiratory signs.

What is the most appropriate approach?

chevron_right Show answer and explanation

A. Diagnose hypertrophic cardiomyopathy and start atenolol

Cardiomyopathy cannot be diagnosed by auscultation, let alone in a 9-week-old kitten. Treating without an echocardiographic diagnosis is not justified.

B. Ignore it: murmurs in kittens are always innocent

Kittens also have congenital heart disease (ventricular septal defect, valve dysplasias). A soft murmur at this age is probably innocent, but you must check that it goes away.

C. Take thoracic radiographs to tell whether it is innocent or pathological

Radiographs can be normal in many mild and moderate congenital defects and do not identify the lesion. The test that separates an innocent from a pathological murmur is Doppler echocardiography.

D. Re-auscultate at the next vaccinations and, if the murmur persists at 4–5 months or gets louder, perform Doppler echocardiography

Correct. A soft murmur in a healthy kitten may be innocent and usually goes by 4–5 months. If it persists, gets louder or signs appear, Doppler echocardiography identifies the cause. It is indicated earlier if the murmur is loud or before anaesthesia.

lightbulb Key takeaway

Use the vaccination visits to re-auscultate: an innocent murmur fades and disappears. In adult cats, murmurs are often dynamic (right or left ventricular outflow tract obstruction) and do not always mean heart disease, but their absence does not rule it out either. When in doubt, echocardiography.

What is the most appropriate approach?

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