A lot of people all over the globe have come to love the 20th century Cavalier King Charles Spaniels. This breed of dog, usually considered as toy dog and historically considered as lap dog is one of the affectionate, playful and extremely patient breed of dogs in existence. They are even termed "the ultimate lap dog" or the "love sponge" of dogs because of their outstanding temperament.

But despite the affection they have in their hearts, Cavalier King Charles Spaniels can suffer from quite a few genetic defects that can pose danger to their health - one of which is mitral valve disease. As the name implies, mitral valve disease (MVD) is a degeneration of the heart's mitral valve. This happens when the hinge on the heart's mitral valve loosens thus unable to close fully after each pumping action. Because of this, the blood flows backward through them from the ventricle back to the atrium. This degeneration causes heart murmurs and later congestive heart failure even at an early age. MVD affects more than half of all Cavalier King Charles Spaniels by age five and nearly all of them by age ten. In fact, this disease is the leading cause of death of Cavalier King Charles Spaniels all over the world.

No sane dog owner would ever want this to happen to their beloved canine friend, right? In order to prevent this disease, and of course to lengthen your pet's life, your Cavalier should be screened for heart murmurs every year beginning at age one year. Take note that there other causes for heart murmurs. Your vet may hear heart murmur on the left side but that  doesn't necessarily mean it is because of MVD. The disease is diagnosed depending upon where the regurgitation is heard through monitoring using stethoscopic examinations, x-rays, echocardiograms and color Doppler echocardiograms.

Breeders play an important role in the prevention and spread of the disease. A reputable breeder knows that more than half of all Cavaliers as young as five years of age maybe affected with the disease; thus they should not be bred. Even Cavaliers of more than five years of age should not be bred if it developed an MVD before the age of five years. It is also important that those who will be included in the breeding process should be examined by veterinary cardiologists and cleared by veterinary specialists for MVD.