Chapter 26 Diseases of the Cardiovascular System
The structure of the heart and vasculature of the bird is similar to that of the dog and cat. The bird heart is larger than the mammalian heart compared with body mass, and the heart is designed for rapid depolarization, which is important with a rapid heart rate. The aortic arch is derived from the right arch, not the left as in mammals, and the circulatory system contains two important portal systems: the hepatoportal and the renal portal system. The avian heart is designed for high performance. However, heart disease in pet birds is rarely recognized. Abnormalities in chickens and turkeys have been linked to nutritional deficiencies, infectious diseases, hypertension, toxicities, and primary congestive heart failure, but cases of these diseases in pet birds have not been well documented for several reasons. The heart rate of the normal bird will vary by species (600–750 beats/min in parakeets to 120–780 beats/min in parrots); thus it is often difficult to auscultate murmurs or other defects, and electrocardiography in the avian patient is cumbersome.