Dear Dr. Thompson: I have a twelve year-old toy terrier who gets his annual check-ups and has always been healthy. He was diagnosed with a mild heart murmur years ago and he has it checked every year. He seems to cough when he drinks or gets up from sleeping. My veterinarian says he doesn’t need any medication at this time. I wanted to know if the coughing events are due to his heart murmur and it might be getting worse. Do we need to have his murmur evaluated? If it is worse, then what is the usual treatment for this condition?
A heart murmur is a disruption in blood flow through the heart that is typically heard through a stethoscope. A murmur can be a result of a leaky valve, narrowing of the major blood vessels or a change in the size of the heart. Sometimes where the murmur is heard will give you a clue as to what the problem may be.
His breed at this age most commonly develops a leaky mitral valve, which is the major valve between the upper and lower chambers of the left side of the heart. The backflow of blood through the leaky valve can eventually stretch out the upper chamber or left atrium. Eventually the function of the heart can be affected and the body doesn’t pump blood as efficiently, leading to fluid accumulating in the lungs. This fluid could be the cause of a mild cough and would be a sign of what is called congestive heart failure. Many times the cough is worse after lying down or sleeping.
Another potential cause could be if the enlarged left atrium is pushing on the main branch of the windpipe as it diverges into each lung. This cough is less predictable.
Chest x-rays would be first step to evaluate the size of the heart and to see if there is evidence of fluid accumulating in the lungs. An ultrasound of the heart called an echocardiogram will help to evaluate the source of the murmur and determine if there has been any change in the size or strength of his heart.
If there is evidence of heart failure, a number of medications can improve his quality of life. However, the first step will be determining if there is truly any evidence of failure. If his heart is functioning well, other sources of a chronic cough might need to be investigated. The first step would be getting in to see your veterinarian to make sure it is nothing to worry about.