While there are many types of heart disease that may affect your dog, one of the most common is degenerative valve disease. The mitral valve, which is found between the left atrium and the left ventricle, is especially prone to degenerative valve disease while the tricuspid valve (between the right atrium and right ventricle) can also be affected. The effect of degenerative valve disease is that the valves themselves begin to leak resulting in a heart murmur. In a healthy heart, blood flow from the atrium to the ventricle is controlled by these valves. However, dogs with degenerative valve disease develop this murmur which is caused when blood moves backwards into the atrium.
As degenerative valve disease progresses, the leaky valve causes too much blood to accumulate in the atrium and ventricle causing these heart chambers to expand. Over time, the pressure in the heart builds up and may even affect other organs. In mitral degenerative valve disease, blood may leak out of blood vessels into the lungs leading to congestive heart failure. In tricuspid degenerative valve disease in dogs, fluid can leak from the chest into the abdominal cavity causing a large abdominal cavity that looks like a bloated abdomen.
In most cases, degenerative valve disease in dogs mostly affects older, small breeds and the disease is more prevalent in males. Some breeds that are predisposed to degenerative valve disease include Miniature poodles, Cocker Spaniels, Dachshunds, terriers, and Miniature Schnauzers. Unfortunately, treatment of degenerative valve disease rarely cures the condition. Instead, veterinarians aim to alleviate the symptoms of congestive heart failure and by removing any fluid that may build up in the abdominal cavity. For dogs, degenerative valve disease is the most common cause of heart failure and there may be little you can do to prevent death. Because heart failure due to degenerative valve disease in dogs normally affects older dogs, veterinarians will encourage taking steps to improve the comfort of your dog during his final days.