A dilated cardiomyopathy, or DCM, is an acquired heart disease common in certain large breeds of dogs. DCM is a condition in which the heart's ability to pump blood is decreased because of enlargement of the heart's chambers and thinning of its walls. The obviously visible symptoms of this canine heart disease include loss of appetite and subsequent weight loss, weakness, coughing, fainting, rapid heart rate, and general malaise. With a stethoscope, a veterinarian can readily diagnose an arrhythmia and X-rays can show an enlarged heart, but the most thorough test is an echocardiogram, or ultrasound of the chest. The echocardiogram is helpful to determine how the heart is functioning and in establishing an accurate prognosis.
Great Danes, Doberman Pinschers, Boxers, and Cocker Spaniels are those breeds most frequently afflicted with DCM, but any dog can be affected. Often, vigilant breeders will have those dogs that are commonly affected screened for a predisposition to DCM before including them in a breeding program. Although no specific gene has been isolated, and no blood test can determine if a dog carries DCM, a device known as a Holter monitor can be used to collect data. The patient wears a tightly fitted vest which monitors the heart rate and rhythm over a 24-hour period. The data is then uploaded and analyzed for potential signs of the disease.
Another cause of a dilated cardiomyopathy is a taurine deficiency. But because all commercially prepared canine (and feline) diets are supplemented with this amino acid in the United States, it is relatively uncommon cause in the U.S. However, if a pet is recieving home-prepared meals, this taurine deficiency may be considered.
Once diagnosed, the disease progresses quickly and is fatal. Medications may control the arrhythmia, improve heart function, and keep excess fluids from accumulating in the chest and abdomen, but heart failure is inevitable. Therefore, even though these medicines improve the quality of life and lifespan, the holster monitor and its ability to detect the predisposition to DCM is a much more effective tool in helping combat this disease.
For more information on symptoms, diagnosis, treatment, and prognosis of DCM, see our expanded article on Dilated Cardiomyopathy in pets.