Causes of Canine Dilated Cardiomyopathy

Canine dilated cardiomyopathy is a condition that leads to the enlargement of the heart chambers and weakening of the heart muscles. This in turn impairs cardiac function. Dilated cardiomyopathy is the most common heart disease to strike middle aged and large breed dogs such as:

  • Great Danes
  • Dobermans
  • boxers
  • mastiffs
  • Irish wolfhounds

and some medium sized breeds such as English Springer Spaniels and cocker spaniels.

Dilated Cardiomyopathy

The heart of a dog affected by dilated cardiomyopathy loses its capacity to contract. The muscle wall of the left ventricle is thick in normal hearts but becomes thinner in hearts affected by this disease. There is a simultaneous irregular heartbeat as a result of the heart’s incapacity to contract. The heart thus fails to pump the required amount of blood and there is an increased volume of blood in the ventricle.

The increase in pressured due to the increased volume of blood and the thinning of the muscle wall, allows the ventricle to increase in size and leads to enlarged heart chambers.

Symptoms of Canine Dilated Cardiomyopathy

  • Intolerance to exercise
  • Difficulty in breathing
  • Cough
  • Lethargy
  • Depression
  • Loss of appetite
  • Loss of weight
  • Increased thirst
  • Accumulation of fluid in the abdomen
  • Vomiting
  • Collapse

Causes of Canine Dilated Cardiomyopathy

In most dogs, the cause of canine dilated cardiomyopathy is unknown and this is true for primary dilated cardiomyopathy. However, a variety of problems can affect the myocardium adversely and lead to secondary dilated cardiomyopathy. Some of the common causes are:

  • genetic factors
  • metabolic disorders
  • inflammations
  • nutritional deficiencies
  • immunologic abnormalities
  • trauma
  • toxins
  • amino acid deficiency
  • taurine deficiency


Large and giant breed dogs are genetically predisposed to this disease whereas small and toy breed dogs are rarely affected by it. It has been found that male dogs are more predisposed to dilated cardiomyopathy than female dogs and middle aged or older dogs are more likely to contract this disease.

Nutritional Deficiencies

Abnormally low amounts of the amino acid Taurine in the blood plasma can cause dilated cardiomyopathy in dogs. This is especially true in the case of cocker spaniels and golden retrievers. Dogs on exclusive vegetarian diets have taurine deficiency. In addition, deficiency of Lcarnitine in the dog’s diet can result in less energy being supplied to heart muscles and can cause dilated cardiomyopathy. Occasionally, due to metabolic disorders, the dog can’t assimilate the Lcarnitine present in his diet and this can cause the deficiency.


Toxins such as the drug doxorubicin, ethyl alcohol, cocaine, lily of the valley, foxglove and buttercups can result in the degeneration of heart muscles and impaired cardiac function associated with dilated cardiomyopathy.


Infection by parvovirus can cause dilated cardiomyopathy in young puppies. Distemper is another disease that can damage heart muscles of surviving dogs and cause dilated cardiomyopathy.


Parasites such as heartworm and Trypanosoma cruzi are known to cause chronic symptoms of dilated cardiomyopathy in surviving dogs.

Metabolic Disorders

Disorders affecting normal metabolism such as diabetes, hypothyroidism and pheochromocytoma are also associated with canine dilated cardiomyopathy.

Although there is no cure for dilated cardiomyopathy in dogs, proper diet, treatment and rest can increase the life expectancy of your pet. The prognosis depends upon early diagnosis and proper treatment. However, it should be kept in mind that this is a progressive and fatal disease.