Atrioventricular Valve Dysplasia in Dogs

What does it mean that my dog has been diagnosed with atrioventricular (AV) valve  dysplasia?

heart-atrioventricular_valvular_dysplasiaThere are four chambers in the dog’s heart – two top chambers (the atria) and two bottom chambers (the ventricles). There are valves that separate the top chambers from the bottom chambers. These are the atrioventricular (AV) valves. The valve on the right side of the heart is called the tricuspid valve, and it has three parts. The valve on the left side of the heart is called the mitral valve, which  has two parts. As the heart contracts, the blood is pumped into the lungs from the right ventricle and out to the rest of the body from the left ventricle. When the AV valves are healthy, they act to prevent the backflow of blood from the ventricles to the atria during contraction of the heart.

AV valve dysplasia describes a developmental malformation of the mitral or tricuspid valve, and may be referred to by the specific valve that is affected. Dysplasia may occur in both the mitral and tricuspid valves in the same dog, but this is not a common condition.

Are some breeds more likely than others to be born with abnormal AV valves?

Bull Terriers, Newfoundlands, Great Danes, Golden Retrievers, and Dalmatians are recognized to be susceptible to develop mitral valve dysplasia.

Labrador Retrievers, German Shepherd Dogs, Great Pyrenees, and Old English Sheep Dogs are recognized as susceptible to tricuspid valve dysplasia.

What are the signs of AV valve dysplasia?

The signs of AV dysplasia are variable, but most often begin within the first few years of life. More males than females develop heart failure from valve dysplasia. Exercise intolerance, accumulation of fluid in the abdomen, weight loss, and stunted growth may be seen. Difficulty breathing or collapse may occur if congestive heart failure develops.

Signs specific to mitral valve dysplasia (left side of the heart) include:

  • Heart murmur, possibly with vibrations that can be felt on the side of the chest
  • Rapid breathing
  • Coughing from fluid accumulation in the lungs
  • Bluish discoloration of the mucous membranes when inadequate oxygen is being circulated by the failing heart

Signs specific to tricuspid valve dysplasia (right side of the heart) include:

  • Heart murmur, possibly with vibrations that can be felt on the side of the chest
  • The jugular veins in the neck may be enlarged or have a pulse
  • Fluid may accumulate in the abdomen or in the soft tissues of the legs

Your veterinarian will want to x-ray your dog’s chest as part of the diagnostic plan. Ultrasound imaging of the heart (echocardiography) generally provides the definitive way to confirm the diagnosis and to monitor progression of heart failure.

How is AV valve dysplasia treated?

Treatment of AV valve dysplasia is focused on managing signs of congestive heart failure. Activity may need to be restricted based on the dog’s exercise tolerance. The dog may faint with increased exercise or if the heart suddenly beats in a rapid irregular rhythm. Nutritional changes may be recommended in order to restrict sodium. Your veterinarian will determine which medications should be prescribed.

Unfortunately, the prognosis for AV valve dysplasia is guarded to poor. The affected dogs should not be used for breeding due to the heritable nature of valvular disease.

This client information sheet is based on material written by: Robin Downing, DVM, DAAPM, DACVSMR, CVPP, CRPP

© Copyright 2015 LifeLearn Inc. Used and/or modified with permission under license.

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