Pet doctor: Some breeds suceptable to heart ailment

When people find out you're a veterinarian, they often ask you for casual advice about their pets.

The guy who owns the gym we work out at here in Mexico brings his French mastiff to work with him every day. He recently told me that his veterinarian diagnosed the dog with heart disease and told him he didn't have very long to live. He didn't know the specific diagnosis, but he did know that his dog had an arrhythmia that was detected using an electrocardiogram.

Without even having my stethoscope with me, I could speculate that the dog likely has DCM, or dilated cardiomyopathy. This is a common type of acquired heart disease in dogs and often affects large and giant breeds. The symptoms that owners can see include weight loss and loss of appetite, lethargy, coughing, fainting, and rapid heart rate. A veterinarian can typically hear an arrhythmia with a stethoscope, but X-rays will often show a uniformly enlarged heart as well. Echocardiogram, which is an ultrasound examination of the heart, can confirm the diagnosis, but often the presence of an arrhythmia and an enlarged heart in a commonly affected breed is enough to make the diagnosis. In a dog with severe clinical signs, the echocardiogram is helpful to determine the degree of decreased heart function and establish prognosis.

Boxers, great Danes, Doberman pinschers, and Cocker spaniels are breeds that are frequently affected by DCM, but it can occur in any dog. Responsible breeders will often have their dogs screened by a veterinary cardiologist for DCM before considering a dog for inclusion in a breeding program, if that breed is known to be commonly affected. This is extremely important, since a genetic predisposition is suspected, although no specific gene has been isolated, and there is no blood test to determine if a dog carries DCM. Because affected dogs can appear normal for some time, screening is especially important. A device known as a Holter monitor may be used to collect data about the heart rate and rhythm over a 24-hour period. The monitor is housed in a tightly fitting vest that is worn by the patient, and then the data is uploaded and analyzed to look for potential signs of the disease.

Another cause of DCM is a deficiency of the amino acid taurine. Because all commercially prepared canine (and feline) diets are supplemented with taurine, this is uncommon in the U.S., but it is possible for animals to acquire DCM if they are eating a poorly balanced home-prepared diet, such as a vegetarian diet.

Unfortunately many of these dogs die acutely, often before their owners knew anything was wrong. Once diagnosed, it is a progressive and ultimately fatal disease. Medications may help improve the quality of life and extend lifespan. The patient will ultimately go into heart failure, if it isn't present at the time of diagnosis. Treatment focuses on controlling the arrhythmia, improving heart function, and keeping fluid from accumulating in the chest and abdomen.

Christie Long is a veterinarian at the VCA Fort Collins Animal Hospital. Call her at (970) 204-4567 or send email to thepetdoctor@gmail.com.