Heart Murmurs in Dogs: Grades, Prognosis and Treatment

An abnormal whooshing sound from turbulent blood flow. Murmurs aren't a disease - they signal something else, from harmless (innocent puppy murmurs) to serious (valve degeneration, cardiomyopathy).

Graded I-VI by loudness. Grade I barely audible. Grades II-III soft to moderate. Grades IV-V loud with chest vibration. Grade VI loudest. Higher grade doesn't always mean worse disease but warrants investigation.

Many do. Innocent murmurs (Grade I-II) often disappear by 4-5 months. Congenital defects cause murmurs that won't resolve. Your vet should keep an eye on it at each puppy visit.

Echocardiogram costs $300-$600 at a general practice, $400-$800 at a cardiology specialist. It shows chamber size, valve function, blood flow, and muscle thickness. Sedation adds $50-$100.

Common: pimobendan (strengthens contractions), furosemide (removes fluid), enalapril/benazepril (ACE inhibitors), spironolactone. Combination depends on disease type and severity. Monthly costs $50-$200.

Many do - especially with innocent or low-grade murmurs. With medication, dogs with heart disease keep a good quality of life for years. What matters most: early detection, consistent medication, and regular echocardiogram monitoring.

Persistent coughing at night, rapid breathing at rest, a strong reluctance to exercise, fainting, swollen abdomen, bluish gums, weight loss. See your vet urgently - heart failure needs treatment adjusted right away.

Most policies cover diagnosis and treatment as standard illness coverage. The catch: murmurs detected before enrollment are denied as pre-existing. Long-term medication coverage varies - some plans have annual or per-condition caps.

A murmur is a sound, not a diagnosis, so the honest answer depends on what is causing it. Soft innocent murmurs in puppies usually disappear by 4 to 6 months of age and carry no effect on lifespan at all. When the cause is mitral valve disease, the most common reason for a murmur in older small dogs, the course is often slow: in a study of 558 dogs, more than 60% of those without symptoms were still alive after almost 6 years of follow-up, and in dogs whose heart had already enlarged (stage B2) pimobendan delayed the onset of heart failure from a median of 766 days to 1,228 days. Once congestive heart failure develops (stage C) the median time to a cardiac death or treatment failure in the QUEST trial was 267 days on pimobendan versus 140 days on benazepril, but many individual dogs lived well beyond that. Your dog is not a median; an echocardiogram tells your veterinarian which stage applies, and that is the number that matters for your dog.