The avian heart is an amazing organ. Because birds are so athletic, they have relatively bigger hearts than that found in mammals. (Anyone who has shared a home with a bird knows about their big hearts!) Not only is the heart bigger in birds, but it also beats a lot faster, relatively. For example the cardiac output (the blood flow out of the heart) is about seven times greater in a flying budgerigar (parakeet) than in a person or dog at maximum exercise level! Birds also must have a higher blood pressure than mammals to go along with that increased blood flow from the heart. Anatomically, birds have four chambers to the heart, which is the same amount as mammals. They are: right and left atrium, and right and left ventricle. You don’t hear much about birds and heart disease, but it does occur, although not as often as it occurs in mammals. Do birds get heart attacks? Well, that’s a complex question. Birds have an excellent blood supply to their heart muscle, as would be expected with an athletic animal. A heart attack occurs when, over time, the blood vessels that supply the blood, oxygen and nutrients to the heart muscles become obstructed to the point that the muscle cells begin dying. The most common reason for obstruction to the heart’s blood vessels is from atherosclerosis, which is a buildup of plaques inside the blood vessels. This seems to occur most often in African grey parrots but can occur in any parrot species. In people, it was discovered that there were Chlamydophila organisms (the primitive bacteria responsible for psittacosis) under some plaques in the blood vessels. This is an interesting discovery, and one that I have not heard diagnosed in birds, but one that warrants further study, since the connection between birds and psittacosis is well-known. Other heart conditions are more common in older birds, including congestive heart failure. This occurs when the heart no longer acts as an effective pump, and the blood supply to the kidneys is often compromised. In some cases, there is fluid in the sac around the heart itself, preventing it from pumping optimally. In other cases, the heart may become too muscular or too flabby, with both conditions causing ineffectual pumping. If the right side ventricle fails (or both ventricles are failing), then usually there is an enlarged liver, fluid found in the body tissues (called edema) and also excessive fluid in the body cavity. If the left ventricle fails, there is usually excess fluid in the lung tissue. When performing a physical exam on a pet bird, your avian veterinarian will auscult (listen to with a stethoscope) to the heart, lungs and air sacs of your bird. The heart rate and rhythm will be evaluated. Most birds have a really fast heart rate, and it is easier to evaluate when under anesthesia, as the rate often slows down. Some birds have an arrhythmia, meaning that the heart rhythm isn’t always the same, and may speed up or slow down based on breathing or for other reasons. Some birds may have a heart murmur, which means that there is abnormal blood flow in the heart and through one or more of the valves. This in itself doesn’t mean that the bird had a problem, but those identified with a heart murmur should be followed more closely and undergo a cardiac work-up either before a problem occurs or if signs of a heart problem begin to show up. A cardiac work-up includes baseline blood tests, radiographs to evaluate the heart, lungs, air sacs, liver and other internal organs, and perhaps an echocardiogram or electrocardiogram or special dye studies of the heart and blood vessels. I also suggest testing for Chlamydophila, although testing is never 100 percent in a live bird. Older birds, overweight birds and perhaps inbred birds are more likely to develop heart disease. I have seen a few cases of congenital or developmental heart disease, as well.
