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If your dog has been diagnosed with a heart murmur, you are probably wondering what it means and what comes next. One of the most common causes behind heart murmurs in dogs, especially mature, smaller breeds, is Myxomatous Mitral Valve Disease (MMVD). In this article, we’ll explore what MMVD is, the symptoms to watch for, how it is treated, and how TACC helps dogs live longer, healthier lives through expert diagnosis and care.
MMVD, also called chronic valvular disease or mitral valve degeneration, is a progressive condition where the mitral valve in the heart becomes thickened and leaky. This valve normally controls blood flow between the left atrium and the left ventricle. As this valve changes with age, blood leaks backward, causing dilation to the heart and increasing stress within the heart.
This disease tends to affect:
The tricky thing about MMVD is that it often starts without any obvious symptoms. Your pup might feel perfectly fine, but during a regular checkup, your veterinarian hears a heart murmur. This is often the first clue.
Over time, the disease progresses in stages:
At TACC, our board-certified cardiologists use advanced echocardiography to pinpoint a patient's exact stage of heat disease and start treatment early—when it can make the biggest difference.
Treatment depends on the stage of the disease. Here’s a breakdown:
Stage B2:
Stage C or D:
Surgical options for mitral valve repair or replacement exist at select specialty centers, although such procedures are not widely available or suitable for every patient.
Sometimes the early signs are subtle and easy to miss. Keep an eye out for:
A normal resting breathing rate is less than 35 breaths per minute. Consistently counting a higher breathing rate, especially if the resting breathing rates are greater than 60 breaths per minute, may be indicative of an emergency.
Available medical treatments are designed to slow the disease, ease symptoms, and improve quality of life. In a few specialized centers, heart surgery (valve repair or replacement) is possible, but it is not widely available or feasible in all patients.
How long can my dog live with MMVD?
Many dogs with only a heart murmur (early MMVD) may live their normal life span without ever developing heart failure. Starting early therapy, if indicated, will slow progression into heart failure. If heart failure develops, treatment with a board-certified cardiologist can often give your dog a year or more of good quality life, depending on their response to medication and how early treatment is started.
Should my dog have exercise restrictions?
Most dogs with MMVD benefit from light to moderate daily activity, such as short walks. This helps maintain muscle tone and mental health. Strenuous exercise, long hikes, or intense play should be avoided, especially once symptoms appear. Ask your cardiologist for advice specific to your pet.
Does diet matter for MMVD?
Excess salt (sodium) can make fluid retention worse, but restricting sodium too early in the disease state is also detrimental. Your cardiologist may suggest a prescription cardiac diet in later stages of the disease, but in early stages, keeping your dog on a balanced, high-quality diet is best.
What medications are used for MMVD?
Common medications include:
Your dog may need one or several of these medications depending on the stage of disease.
Will medications make my dog sick?
Most dogs tolerate heart medications very well. The most common side effects are increased thirst and urination from diuretics or occasional stomach upset. At TACC, our team carefully monitors patients with physical examinations, blood work, imaging and all available medical information to ensure medications stay safe and effective, adjusting treatment as the disease changes over time.
How often should my dog be checked?
For dogs with just a murmur, no symptoms with no required medications, a check-up every 6–12 months is typical. Once medication is started or if heart failure develops, visits may be needed every 3-6 months, or more frequently in severe disease (stage D). At The Animal Cardiology Center, our cardiologists create a personalized recheck plan for each patient. Frequent and planned, well-timed visits allow us to adjust treatment before problems become emergencies. However, if changes in clinical signs are seen at home, then a recheck examination should be made prior to the prescribed time.
MMVD might sound scary at first, but with early detection, personalized care, and expert guidance from The Animal Cardiology Center, you and your pet can face it head-on, armed with the most up-to-date knowledge. If you’ve noticed a murmur, cough, or any unusual signs, don’t wait. Schedule an appointment with our board-certified cardiologists today.
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