In veterinary medicine right-to-left cardiac shunts are usually the result of pulmonary arterial hypertension that increases pressure in the right side of the heart leading to a reversal of blood flow through a congenital malformation.1,2 This case report describes the treatment of presumed pulmonary hypertension and a right-to-left cardiac shunt in a mealy Amazon parrot (Amazona farinose).
A 25-yr-old male mealy Amazon parrot with a history of polycythemia, hepatomegaly, and epistaxis was evaluated for progressive lethargy and anorexia. Clinical laboratory testing revealed severe polycythemia (71%), hypophosphatemia (1.6 mg/dl), and mild hypokalemia (2.8 mEq/L). Radiographs showed marked hepatomegaly and loss of air sac space. The bird tested negative for West Nile virus and Chlamydia psittaci via PCR. Despite supportive treatments, the bird’s condition deteriorated over the next 24 hr. The patient developed ataxia, had poor flying ability, and became oxygen dependent. An echocardiogram, including a bubble study, performed while the patient was hospitalized showed a right-to-left atrial shunt and presumed pulmonary hypertension. The bird was started on periodic phlebotomy (5–10 ml/kg every 6 wk) to reduce PCV and sildenafil citrate (2.5 mg/kg p.o. q 8 hr) to decrease pulmonary hypertension. One week later the patient was weaned off oxygen. Twenty-four days after initial presentation the parrot was returned to its outdoor exhibit. Intermittent periods of increased respiratory rate and effort have been reported but have resolved without additional treatments. Epistaxis, once common in this bird, has not been noted since initiating treatment with sildenafil citrate, which the bird continues to take well.
The authors thank the staff at the Sacramento Zoo for caring for this bird. Thanks to Thomas J. Morrison DVM, DACVIM (Cardiology) and Sarah Silverman DVM, DACVIM (Cardiology) for their assistance with this case.
1. Buchanan JW. Prevalence of cardiovascular disorders. In: Fox PR, Sisson D, Moise NS, eds. Textbook of Canine and Feline Cardiology. 2nd ed. Philadelphia, PA: Saunders; 1999:457–470.
2. Wood P. The Eisenmenger syndrome or pulmonary hypertension with reversed central shunt. Br Med J. 1958;2:755–762.