Degenerative mitral valve disease (DMVD—also called myxomatous mitral valve degeneration) is the most common type of acquired heart disease in older dogs. The first sign of this disease is usually a heart murmur heard with the stethoscope by your primary care veterinarian.
DMVD can affect all four valves of the heart but the mitral valve is most affected. DMVD primarily affects older, small breed dogs but can also affect some larger breed dogs. Some smaller breed dogs can be affected earlier in life than others with the Cavalier King Charles Spaniel and Chihuahua being the most common breeds of dogs diagnosed with DMVD.
The mitral valve:
PLEASE NOTE: If your dog is experiencing coughing, labored breathing and/or a persistent increase in its resting breathing rate, they should be seen by your primary care veterinarian or an emergency veterinarian as these symptoms may indicate congestive heart failure of which can be a life threatening condition.
If a primary care veterinarian hears a heart murmur in a dog or cat, they may refer the pet to be evaluated by a Board-certified Veterinary Cardiologist to have an echocardiogram (ultrasound of the heart) performed. This specialized ultrasound is the gold standard for definitive diagnosis of the cause of a heart murmur. The results of the echocardiogram will help the cardiologist determine what medications may be required to treat a pet. There are a few international centers that can perform surgery on the mitral valve, however, this is not standard or typical treatment now in veterinary cardiology.
After DMVD is diagnosed, treatment depends on whether a pet’s heart is enlarged. Recent studies have shown that medication will delay the onset of congestive heart failure (CHF) in dogs with moderate to severe secondary heart enlargement caused by the leak in the mitral valve.
A cardiologist will tailor treatment to both delay the onset of CHF and to treat the signs associated with congestive heart failure. Medications may include some or all of the following:
The frequency of follow-up is largely dependent on how severely a dog is affected by DMVD. However, it is usually recommended that a pet is rechecked with their cardiologist every 4-12 months. Blood work to assess kidney function and electrolytes is usually recommended within 2 weeks of starting any medication and every 3-6 months if the dog is maintained on heart medication. Rechecks with a cardiologists may involve both chest x-rays and/or repeat echocardiograms.
The prognosis for newly diagnosed DMVD varies widely. The average time from when a heart murmur from DMVD is first heard until congestive heart failure is present is approximately 3-4 years. However, the speed of progression of the disease is difficult to predict for individual patients and can be quite variable.
Once a patient has developed congestive heart failure, the average survival time is 12-18 months, although this can vary as well. The most frequent cause of death for DMVD patients in congestive heart failure is euthanasia due to either inability to control the signs of congestion (no matter how much medication is given) or inability of the patient to tolerate the amount of medication needed to control congestion.