Virginia Cavalier King Charles Spaniels

 Common Heart Murmurs Heard in CKCS
There are several types of heart murmurs heard frequently in CKCS. They may be innocent, flow murmurs not suggestive of disease, or pathologic, indicative of genetic, inhereditable valvular heart disease.

Innocent, flow murmurs. These murmurs are caused by normal turbulent blood flowing across heart valves of young dogs. These low-grade murmurs (less than a grade 2) decrease with age as the heart matures and are not associated with congenital heart disease.

Murmurs associated with heart disease. CKCS are susceptible to abnormalities of heart valves on both the right and left side of the heart. These abnormalities may be present and evident at birth and therefore are considered congenital. Examples of these include aortic and pulmonary stenosis and the patent ductus abnormality. Mitral valvular disease is considered separately and is felt to represent an adult (mature dog) onset, representing genetic heart disease. The valve itself is normal at birth, but in some dogs degenerates prematurely and sometimes rapidly, leading to disease.

Careful physical examination and additional testing facilitates the diagnosis in a young, asymptomatic dog. Over time, progressive deterioration of the congenitally abnormal valve produces symptoms. Narrowing of the pulmonary valve (stenosis) is the most common valve affected on the right side of the heart. On the left side of the heart, both the mitral valve (leaking or regurgitation) and aortic valve (narrow or stenosis) may be affected.

Mitral Value Disease. Malformation of the mitral valve is characterized by valvular thickening and redundancy and/or degeneration of the muscles which support the valve. These structural changes allow the blood to leak backward from the left ventricle into left atrium during the pumping action of the left ventricle. This systolic murmur is best heard on the left side of the sternum. Progressive leaking leads to enlargement of the left atrium and ventricle. As blood floods the lungs, the animal develops exertional shortness of breath, and has decreased exercise tolerance. Eventually heart failure results.

Guidelines To Reduce The Incidence Of Mitral Valve Disease

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.