Here is info from the

Here is info from the Cavalier King Charles Club web site:

At the 1998 symposium, the panel reported that mitral valve disease is the leading cause of death of Cavalier King Charles Spaniels. Cavaliers are 20 times more prone to have MVD than other breeds. It is hereditary, passed on from generation to generation by the parents, grandparents, and earlier ancestors of our dogs.

The panelists concluded that, ideally, Cavaliers should be 5 years of age or older and heart-clear when they are first bred. However, recognizing the problems associated with breeding females for the first time at 5 years of age, the following was recommended as a secondary approach to reducing the incidence of MVD:

The Brood Bitch should be a minimum of two and a half years old with a clear heart and with both parents with clear heart certificates issued at five years of age or older.

The Stud Dog should be a minimum of two and a half years old with a clear heart and with both parents with clear heart certificates issued at five years of age or older.

All clear heart certificates must be signed by Board Certified Veterinary Cardiologists.

To use an older stud dog with a clear heart certificate issued as late in life as possible is highly desirable. However, an older dog with a slight murmur should not be ignored. It is strongly advised that breeding stock under 5 years old be limited to those with clear heart certificates.

The extent of MVD can be decreased, and the age of onset can be delayed, by breeding only Cavaliers which have been examined by Board Certified Veterinary Cardiologists at age 2 1/2 years or older and found free of MVD murmurs, AND whose parents were similarly examined at age 5 years or older and found to be murmur-free. We refer to these dogs as being “Heart-Clear”.

Raising the age of onset of MVD should be every breeder’s immediate aim. The best way to approach this is to select breeding stock with good heart records behind them. It is strongly recommended that ALL Cavaliers be auscultated (examined with a stethoscope) by a Board Certified Veterinary Cardiologist at 2 1/2 years of age or older and annually thereafter, especially within a year of being bred, and the results submitted to the Health Registry.

These guidelines are based on the current recommendations of geneticists and cardiologists and may be updated and reissued by the Cavalier King Charles Spaniel Club, USA when further research becomes available.