It is not uncommon for cats and dogs to develop some form of heart disease during their lifetime. Early detection is critical to helping prevent congestive heart failure and to help slow the progression of the underlying disease. Many times, the first piece of evidence indicating early heart disease is when your veterinarian hears a heart murmur on a routine physical exam.
A murmur is generated when there is abnormal blood flow through the heart. This can be secondary to a leaking heart valve, a birth defect, or a primary problem with the myocardium, or heart muscle cells. In any of these cases, there will be progression of the problem overtime. If left undiagnosed, ultimately congestive heart failure could occur. With heart failure, fluid backs up in the blood vessels and eventually leaks either into the lungs, around the lungs, or into the abdominal cavity. This causes shortness of breath, cough, exercise intolerance, fainting and potential death.
The presence of a new heart murmur does not always indicate which type of heart disease may be present nor does it say anything about the severity. The only way to know what is causing the heart murmur is to have a veterinary cardiologist perform an echocardiogram, or ultrasound of the heart. This tells us what is making the murmur appear, how severe the changes are, and what medications, if any, are indicated to help slow the disease process and prevent congestive heart failure.
The heart is made up of four chambers separated by one-way valves. One of the most common heart disease, in dogs especially, is a leaking heart valve. As this leak worsens overtime it can cause blood to back up into the heart and cause stretch or enlargement of these chambers. Once the heart can no longer compensate for this overloaded state, congestive heart failure develops.
Another type of heart disease can affect the heart muscle itself. Most commonly in dogs the muscle loses its ability to contract well and therefore cannot circulate blood throughout the body appropriately. In cats it is more often a thickening of the heart muscle which secondarily makes the heart chambers smaller. This makes the heart have to work even harder making it susceptible to heart failure.
If your dog or cat develops a heart murmur, the best way to know what to do for them is to get a diagnosis with a cardiac ultrasound. This will not only help you and your veterinarian know what the problem is, but how often to be monitoring your pet and if there are any medications that may be able to help your pet live a longer, happy, healthy life.
Lisa Edwards, DVM
Green Lake Animal Hospital