Mitral Valve Disease (MVD) is a heart disorder that commonly affects Cavalier King Charles Spaniels. As Cavalier King Charles Spaniels age, a degenerative thickening and progressive deformity can develop that causes the mitral valve (located in the heart between the left atrium and left ventricle) to leak.

Over time, the leak can result in blood pooling behind the heart, causing fluids to accumulate in the lungs and sometimes leading to congestive heart failure.

Unfortunately, there is no prevention and no known cure today for MVD. In mild cases, your Cavalier King Charles Spaniel may have no obvious symptoms of mitral valve disease.

In more advanced cases, a Cavalier King Charles might exhibit heavy breathing, coughing, and reluctance to exercise. On rare occasions, the mitral valve can tear, causing fever and respiratory illness.

Veterinarians may initially detect mitral valve disease as a heart murmur. A chest x-ray can help evaluate whether the heart has enlarged, but an echo-cardiogram is necessary for a definitive diagnosis. Moderate cases are generally not treated at this stage.

Cavalier King Charles Spaniels with advanced mitral valve disease or congestive heart failure may be treated with diuretics (to increase urine to eliminate excess fluids) and vasodilators (to dilate blood vessels) to provide relief and extend the dog’s life. Surgical valve repair or replacement may be an option for some Cavalier Spaniel dogs.

The American Cavalier King Charles Spaniel Club warns that mitral valve disease is a particular problem for this breed. Reports have been made of nearly 50 percent of all Cavaliers developing a valve murmur by the age of 4 or 5, and nearly all Cavaliers showing a murmur by 10 years of age.

Read more about mitral valve disease at here and here.