Congenital Heart Disease in a Young Dog

He was less than a year old. His shiny black coat indicated he had been well cared for and was ready for the good life Labrador Retrievers enjoy. But as he lay on the examination it was obvious he was very sick. He had become acutely ill and as he turned toward me his eyes seemed to say, “It’s no use, Doc”.

          With mouth halfway opened he gasped for breath, but there was no sound of rushing air. I could not feel the femoral pulse. Nor, could I hear the heart beat with a stethoscope. These two signs indicated the heart was not adequately pumping blood. However, the electrocardiogram was not unusual. It could not define the type of heart disease, and he was too ill to do chest radiographs that might be instructive. There were sounds of air movement in the lungs, vesicular sounds, detectable with the stethoscope but no rates or creptations. This and his gasping for breath suggested the lungs were filling with fluid escaping from his blood. This is called pulmonary edema. The dog was treated for dilated cardiomyopathy, a common form of heart failure. And, although he was not coughing he was also treated for influenza, a virus infection which can cause pulmonary edema even though heart failure was considered to be a more likely primary cause of his symptoms.

          He died during the night. The necropsy next morning showed his lungs were indeed edematous. Enough so that, it was obvious he had drowned in fluids that escaped into his lungs from blood vessels due to stasis of blood flow that complicated inadequate heart function. The heart disease was not dilated cardiomyopathy. Rather, it was hypertrophic cardiomyopathy; a condition in which heart muscle cells proliferate increasing heart wall thickness. Scar tissue may form further compromising cardiac contraction. Eventually these changes lead to heart failure and death of the victim. Rare in dogs, it is common in cats in which it is thought to be inherited. I was told litter mates of this dog all died suddenly but no diagnosis of cause of their deaths was rendered. These deaths suggest hypertrophic cardiomyopathy in this young litter was inherited. As a rule, therapy of dogs terminally ill with this disease is not effective. Management of the disease is by prevention. Avoid mating of known carriers.