What Does a Heart Murmur Mean in a Dog or Cat?
A murmur is the sound of turbulent blood flow, graded one to six by loudness — a finding that calls for follow-up, not a diagnosis in itself.
During a checkup the veterinarian listens for the crisp two-beat rhythm of a healthy heart. A murmur is an extra whooshing sound made by turbulent blood flow, and hearing one changes the visit from routine to investigative: the sound says something is stirring the flow, but not yet what or how much.
From a sound to a plan
Murmurs are graded one to six by loudness, but loudness tracks turbulence, not always severity. Some are “innocent”: soft murmurs in growing puppies often fade with age, and lean athletic dogs or stressed cats can generate flow sounds with normal hearts. Others trace to valve disease, muscle disease, or anemia — echocardiography is the tool that tells these apart.
What follows the finding varies by animal: a young dog may simply be rechecked next visit, while a senior small-breed dog or a murmur-plus-symptoms case is usually referred for imaging sooner. If a murmur is mentioned at your pet’s exam, ask the veterinarian at that consult what grade it was and what the recheck plan is — writing both down keeps future comparisons honest.
MediIndex articles are for general information only and are not medical advice, diagnosis, or advertising. Outcomes vary by individual — consult a board-certified specialist for personal decisions.