What you need to know...
The Cavalier King Charles Spaniels breed suffers from a congenital heart disease named Mitral Valve Disease. This condition causes a gradual weakening of the heart's efficiency pumping blood and can lead to a shortened life expectancy. MVD has been shown to have genetic component. Sometimes this condition can be detected by a Veterinarian as a heart murmur in younger dogs.
However, representations by any breeder that MVD will not occur with your puppy should be met with a raised eyebrow. So many older Cavaliers test positive for this condition that no breeder can guarantee your dog will not develop the condition later on in its life- even if its parents are clear of symptoms. It is important to recognize the limitations of health guarantees and to realize the AKC and other registries are not warranties of a healthy puppy.
The first definition of quality breeding can be sized up by seeing how the breeder cares for their own dogs. Buying from a thoughtful and responsible breeder is your best defense against buying an unhealthy puppy, MVD or otherwise. When possible you should meet your breeder in person.
Keep in mind, there can be potential health issues with any dog. Don't let MVD dissuade you from buying a Cavalier King Charles Spaniel. The Cavalier King Charles Spaniel is an exceptional breed. The recipe for happy ownership is: buy a puppy from a reputable breeder you trust, care and feed your dog well, spend time with them and love them. Buying a Cavalier makes this last one easy. The life expectancy of a Cavalier King Charles Spaniel is 11-13 years. A Cavalier that develops MVD may still live to an old age.
All of our adults are tested by a heart-tested by a certified Veterinarian Cardiologist. Even so, these only reduce the likelihood of issues, any Cavalier may still grow up to develop MVD later on in its life.