Mitral Valve Dysplasia in Dogs

The backflow of blood caused by a malformed mitral valve is called mitral regurgitation or mitral insufficiency. The amount of regurgitation may be small or large depending on the severity of the abnormality of the mitral valve. 

MVD is commonly seen in German Shepherds, Great Danes, Bull Terriers, Cavaliers, Poodles, Boston Terrier, Dachshunds, and Mastiffs.  Dogs diagnosed with mitral valve dysplasia should not be bred.

If your dog is having symptoms of mitral valve dysplasia, he should be seen by a veterinarian.  If left untreated, mitral valve dysplasia can be fatal.

Mitral valve dysplasia (MVD) in dogs is the congenital malformation of the heart’s mitral valve.  A normal mitral valve functions as a one-way valve, which flows blood from the left atrium to the left ventricle.  Deformities in the mitral valve cause it not to shut tightly, which results in the backflow of blood into the left atrium.

Symptoms will depend on the severity of the mitral valve dysplasia. Patients with mild mitral valve dysplasia may not show any clinical signs for months or even years.

• Heart murmur found at a wellness check
• Gagging
• Hacking cough
• Lack of stamina
• Weakness
• Dyspnea
• Congestive heart failure (will cause pulmonary edema, abdominal ascites, retention of fluids in the skin and collapse)

Mitral valve dysplasia (MVD) is a congenital cardiac condition that causes one or more abnormalities to the mitral valve.   This means that MVD was present at birth. The abnormalities of the mitral valve happened during fetal development. Mitral valve dysplasia is potentially an inherited heart condition.

Mitral valve dysplasia is often discovered during a wellness check.  The veterinarian will detect a heart murmur while he is listening to the patient’s heart. A heart murmur is the sound of turbulence within the heart; a whooshing noise during heartbeats.  The murmur is a good indicator that there is a problem with the blood flow within the heart.  

If the veterinarian hears a heart murmur he may recommend diagnostic tests, such as an electrocardiogram (EKG), x-rays and an endocardiogram. These tests can help determine the cause of the irregular sound and the severity of the condition.  The EKG can detect abnormal heart rhythm.  Chest x-rays can visualize the size/shape of the heart and can also reveal the presence of fluids in the lungs.  The endocardiogram uses sound waves to evaluate the cardiac contractions and measures the amount of blood being pumped by the heart.

Other diagnostic tests that may be recommended are a complete blood count, urinalysis and a serum chemistry panel.  These tests can help determine the overall health condition of the patient.

Asymptomatic (no symptoms) patients diagnosed with mitral valve dysplasia usually do not need medical treatment. They do need to have x-rays every 6-12 months to monitor the size of the dog’s heart. Some veterinarians choose to start medical treatment at this stage and will prescribe beta blockers such as carvedilol and/or Bisoprolol.  

Patients with MVD will need to be on low salt diets.  Overweight dogs will have their diets modified in order to decrease caloric intake. Extreme exertion, high humidity and high heat should be avoided. Supplements, and vitamins, which may be suggested, are Vitamin E, Vitamin C, coenzyme CoQ10, and Omega 3.

Patients with more advanced mitral valve dysplasia may also be prescribed angiotensin converting enzyme (ACE) inhibitors (enalapril and benazepril) to help lower blood pressure. Diuretics may help stimulate the kidneys to remove excess fluids from the body.  Digitalis may be prescribed to help slow the heart rate and strengthen the heart’s contraction. Vasodilators drugs can help the heart, to have a better blood flow.

The veterinarian may refer you to a veterinarian heart specialist, who may recommend the surgical replacement of the valve. Dogs do not respond well to mechanical valves; blood clots usually occur.  Studies show that canine patients do well with porcine valve (pig valves) replacements. The surgery can only be attempted on young dogs that are strong enough to undergo this procedure. The valve replacement is an open heart surgical procedure. The patient usually will need to remain hospitalized for a week.

Patients that respond to the treatment plan will have an improved quality of life.  The treatment plan will be a lifetime commitment.  Follow-up visits will be needed to monitor the your dog’s progress.  The veterinarian will also be checking for any side effects caused by the prescribed medications.

Patients that underwent mitral valve replacement will receive post-operative instructions from the heart surgeon.  The prognosis of a full recovery of MVD, in canines that undergo surgery is good.