Dilated cardiomyopathy (DCM) in dogs is by definition a disease of the muscle of the heart. Essentially, the muscle of the ventricle of the heart becomes weakened and is not able to contract normally. This inability to contract eventually leads to heart failure.
The left side of the heart is affected more commonly than the right side of the heart. However, it is possible for the right side of the heart to be involved as well. In some cases, both sides of the heart may be diseased.
The signs observed will depend on which side of the heart is involved.
- Dogs with dilated cardiomyopathy that involves the left side of the heart will develop signs of left-sided heart failure. This includes fluid build-up in the lungs which results in a cough and breathing difficulties.
- Dogs with dilated cardiomyopathy that involves the right side of the heart will develop signs of right-sided heart failure. Right-sided heart failure results in fluid accumulation within the abdominal cavity and the chest cavity (outside of the lungs.)
- Dogs with disease involving both ventricles will develop signs of both left-sided and right-sided heart failure.
- Because the heart muscle is involved, signs seen may also involve arrhythmias (abnormal heart beats.)
Many Cases of Dilated Cardiomyopathy in Dogs are Genetic and Inherited
There are some breeds of dogs that are more prone to have dilated cardiomyopathy than other breeds. These breeds include:
- Doberman Pinschers
- Great Danes
- Boxers
- Newfoundlands
- Portuguese Water Dogs
- Dalmatians
- Cocker Spaniels
In these breeds, a genetic mutation (or mutations) is likely a cause of the disease. For these dogs, dilated cardiomyopathy is an inherited disease, passed to a puppy by the mother and/or father. However, the dog is likely to be an adult before the disease becomes evident.
In some breeds, the mutated gene that is responsible for causing dilated cardiomyopathy has been identified. In other breeds, it has not. The affected gene is not the same in all breeds.
Dietary Causes of Dilated Cardiomyopathy Related Heart Disease in Dogs
In some dogs, deficiencies of various nutrients may play a role in the development of dilated cardiomyopathy.
- Taurine is an amino acid which is necessary to keep the heart muscle healthy. A diet that is deficient in taurine may cause dilated cardiomyopathy. Vegetarian diets are sometimes found to be deficient in taurine, especially those that are home-cooked and not balanced properly. Some breeds, specifically Cocker Spaniels and Newfoundlands, may not be able to metabolize taurine efficiently, resulting in a taurine deficiency.
- L-carnitine is another amino acid that may be responsible for causing dilated cardiomyopathy when deficient. This is especially true in Boxers.
Other Causes of Dilated Cardiomyopathy Related Canine Heart Disease
Some types of drugs can act as toxins to the heart, causing dilated cardiomyopathy. Doxorubicin (Adriamycin®) is a good example.
Infectious diseases can cause dilated cardiomyopathy in some cases as well, although this is not common. Parvovirus can cause dilated cardiomyopathy when a puppy is infected at a very young age. Trypanosomiasis (Chagas disease) is another example of an infectious disease that can (rarely) cause dilated cardiomyopathy in infected dogs.