Breed-specific variations of cardiomyopathy in dogs
Feb 01, 2008
There are many sources to review the pathophysiology of cardiomyopathy. This article will discuss the various common breed-specific variations of cardiomyopathies.
Dilated cardiomyopathy can occur in any breed, although it is seen more frequently in large-breed dogs. According to the Veterinary Medical Data Base at Purdue University, breeds affected (number of cases in the United States from January 1986 to December 1991) included: Doberman Pinscher (603), Boxer (131), Great Dane (122), Labrador Retriever (73), American Cocker Spaniel (53), Golden Retriever (42), Irish Wolfhound (38), Saint Bernard (29), Springer Spaniel (25), Newfoundland (22), English Sheepdog (18), Afghan Hound (15), Scottish Deerhound (7) and English Cocker Spaniel (5). Pertinent information about some of the most commonly affected breeds will be discussed.Doberman
Doberman Pinschers are the most common breed to develop dilated cardio-myopathy and it is suspected to be inherited by an autosomal dominant pattern. Male Doberman Pinschers generally present with heart failure at a younger age than females, but the overall prevalence of the disease is evenly distributed between males and females. The primary cause of their cardiomyopathy is unknown, but many secondary changes in the muscle have been found, including low cardiac muscle L-carnitine, low myoglobin and abnormal mitochondrial function. L-carnitine levels can be low in the muscle with normal plasma concentrations. Oral supplementation produces poor to no response. The disease is most commonly diagnosed from 7 to 10 years of age and dogs diagnosed at 2 years of age and under appear to have an accelerated progression. Progression of disease in dogs diagnosed older than 6 years tends to be prolonged. Dobermans can be identified in the occult stage with electrocardiogram (ECG), echocardiography and Holter monitoring.
Therapy for dilated cardiomyopathy with congestive failure is the same for all breeds. Dogs in congestive failure typically are treated with furosemide, an ACE inhibitor and pimobendan. Other therapy such as spironolactone and beta blockers, including carvedilol, theoretically are warranted, but clinical studies that prove these medications will improve survival are lacking. Spironlactone may help prevent potassium depletion in cases with low potassium or in cases where hydrocholorthiazide is added to furosemide to control congestive failure. Beta-blockers may help control rate, especially if atrial fibrillation is present.