A 20-year-old sexually intact female African Grey parrot (Psittacus erithacus) was examined at Colorado State University Veterinary Medical Center because of a history of lethargy, hyporexia, weight loss, and ascites of 21 days' duration. Multiple therapeutic coelomocenteses had been performed by the referring veterinarian to maintain the parrot's comfort during the 21 days prior to examination at our facility. Results of fluid analysis and microscopic examination of the coelomic fluid aspirated by the referring veterinarian were consistent with a modified transudate (2.6 g of total protein/L, 112 nucleated cells/μL, and < 100,000 RBCs/μL).
Initial examination at our veterinary medical center revealed that the parrot had a body weight of 0.49 kg (1.08 lb). The keel was moderately prominent, which was suggestive of atrophy of the pectoral muscles. The parrot had a markedly distended abdomen and was tachypneic and dyspneic. The respiratory effort became substantially worse when the parrot was tilted backward at an angle between 45° and complete dorsal recumbency. Cardiac auscultation revealed a regular rhythm and a grade 3/6 holosystolic murmur.
Results of a CBC were within the respective reference ranges; however, plasma biochemical analysis revealed severe hypoproteinemia (1.0 g/dL; reference range,1 3.0 to 5.0 g/dL), hypoalbuminemia (0.4 g/dL; reference range, 1.57 to 3.23 g/dL), and hypocholesterolemia (64 mg/dL; reference range, 160 to 425 mg/dL); a mild decrease in aspartate aminotransferase activity (90 U/L; reference range, 100 to 350 U/L); and a mild increase in bile acids concentration (99 μmol/L; reference range, 12 to 96 μmol/L). Thoracic and abdominal radiography revealed severe generalized cardiomegaly (proportion for the width of the cardiac silhouette to width of the thorax, 70%; reference range,2 51% to 61%; proportion for the width of the cardiac silhouette to width of the coracoid, 745%; reference interval, 545% to 672%) and marked hepatomegaly. Although the pulmonary parenchyma appeared normal, the air sacs were minimally visible because of severe compression from coelomic fluid. There was a reduction in detail of the serosa in the coelomic cavity.
With the parrot standing in an upright position, Doppler ultrasonographic–echocardiographic evaluationa was performed to obtain horizontal and vertical views by use of a ventromedian approach described in another report.3 Specific measurements and calculations for the horizontal view were determined and compared with reference values reported elsewhere.3 A large amount of anechoic fluid was visible between the heart and liver, which was consistent with coelomic effusion. Marked distention of the hepatic venous system was also detected, which was suggestive of severe hepatic congestion (Figure 1). The right atrium (length, 8.4 mm, and width, 8.5 mm; respective reference ranges not established) was believed to be substantially dilated because it was larger in size than the left atrium (length, 6.0 mm, and width, 8.1 mm; reference range [mean ± SD], 4.8 ± 1.2 mm and 10.9 ± 2.5 mm, respectively). The right ventricular chamber was severely enlarged as well, with a marked increase in end-diastolic width (9.3 mm; reference range, 4.8 ± 1.1 mm) and length (21.3 mm; reference range, 11.5 ± 1.9 mm). The interventricular septum appeared to be skewed toward the left ventricle as a result of the severe enlargement of the right ventricular chamber. Thickness of the right ventricular wall (3.4 mm; reference range not established) exceeded that of the left ventricular wall (3.2 mm; reference range not established), and thickness of the interventricular septum (3.2 mm; reference range, 2.5 ± 0.3 mm) was increased. Typically, the left ventricle of a psittacine is heavily walled and approximately 2 to 3 times as thick as the right ventricular wall.4 Thus, echocardiographic findings were indicative of mixed concentric and eccentric hypertrophy of the right ventricle.
Systolic right ventricular myocardial function was severely depressed as determined by an increase in end-systolic width (8.5 mm; reference range, 2.8 ± 0.9 mm) and length (16.8 mm; reference range, 9.2 ± 1.4 mm) and a marked reduction in fractional shortening (9.4%; reference range, 39.6 ± 11.4%). The left ventricle appeared mildly volume contracted (end-diastolic width, 7.3 mm, and end-diastolic length, 20.1 mm; reference range, 9.1 ± 1.5 mm and 23.9 ± 1.9 mm, respectively), and left ventricular systolic function (end-systolic width, 3.1 mm; end-systolic length, 17.7 mm; and fractional shortening, 57.2%; reference range, 7.0 ± 1.1 mm, 22.2 ± 1.9 mm, and 23.1 ± 4.6%, respectively) was considered normal.
Color Doppler echocardiography revealed moderately severe insufficiency of the right atrioventricular valve, with a regurgitant jet that was subjectively assessed to occupy approximately a third of the right atrial area (Figure 1). By use of the simplified Bernouili equation,5 peak velocity of the regurgitant jet through the right atrioventricular valve measured with continuous-wave Doppler echocardiography (4.5 m/s) predicted that the systolic right ventricular pressure was 80.5 mm Hg greater than the right atrial pressure. Absence of pulmonary valve stenosis or obstruction of the right ventricular outflow tract was concluded on the basis of a lack of structural abnormalities because accurate measurements of outflow tract velocity could not be obtained. Because the right atrium and hepatic veins were severely dilated and there was coelomic effusion, the mean right atrial pressure was assumed to be increased to at least 10 mm Hg. Consequently, the systolic pulmonary arterial pressure was estimated by use of Doppler echocardiography to be at least 90 mm Hg. The clinical and diagnostic findings supported a diagnosis of right-sided congestive heart failure secondary to pulmonary hypertension.
Coelomocentesis was performed to improve respiratory function by providing more room for expansion of the air sacs. Clinicians were careful to remove as little fluid as possible to provide patient comfort while minimizing worsening of the hypoproteinemia. After successful stabilization, the parrot was discharged to the owner later the same day with instructions to administer several cardiac medications, including furosemide (1 mg/kg [0.45 mg/lb], PO, q 12 h), benazepril (0.5 mg/kg [0.23 mg/lb], PO, q 24 h), and pimobendan (0.25 mg/kg [0.114 mg/lb], PO, q 12 h). It was also recommended that the parrot be fed a high-protein diet.
One week later, the parrot was returned to our veterinary medical center for reevaluation. The owner reported that the parrot was doing better and had improvements in attitude and appetite. Although less abdominal distention was evident during physical examination and the respiratory rate and effort had improved, the keel appeared more prominent, which suggested additional muscle atrophy. Renal function remained normal, as estimated on the basis of uric acid and phosphorus concentrations. Although the amount of coelomic fluid was subjectively assessed as being reduced on an echocardiogram, there was still a substantial amount of effusion. The combination diuretic spironolactone-hydrochlorothiazide (1 mg/kg, PO, q 12 h) was added to the medications administered to the parrot.
Although reportedly doing well on the prescribed cardiac medications, the parrot was found dead in its cage by the owner 35 days after initial examination at our veterinary medical center. Necropsy revealed that the coelomic cavity contained approximately 10 mL of serosanguineous fluid with mild hydropericardium and pericardial thickening. The heart had a globoid appearance with marked dilatation of the right ventricle. The ratio of the thickness of the right ventricular free wall to thickness of the left ventricular free wall was approximately 1:1. Gross examination of the ascending aorta and main pulmonary artery revealed diffuse and irregular thickening with lumens that were variably narrowed. The liver was diffusely pale gray in color but of normal consistency.
Histologic examination of the pulmonary vasculature revealed circumferential expansion of the tunica media and subintimal layers of the large pulmonary arteries attributable to multifocal scattered islands of hyaline cartilage suspended in amphophilic to basophilic ground substance (Figure 2). The resultant thickening of the tunica media and subintima substantially narrowed the vessel lumens. Admixed multifocally within the subintimal layer were aggregates of acicular clefts, which was consistent with cholesterol clefts and accumulations of eosinophilic edema fluid. Endothelial cells were vacuolated with radial orientation of their nuclei into the lumen. Use of Verhoeffvan Gieson stain revealed multifocal scarcity to a total lack of the internal elastic lamina, with thin, irregular medial elastin fibers. Medium-size pulmonary arteries within the lungs were similarly affected. Within sections of the heart, there was multifocal epicardial fibrosis with varying degrees of subepicardial interstitial fibrosis. Adjacent to areas of fibrosis were numerous ectatic lymphatic vessels. Cardiac myoctes within affected areas were moderately reduced in cross-sectional diameter, vacuolated, or both. In some sections of liver, the fibrous perivascular capsule (ie, Glisson's capsule) was thickened as a result of organized fibrin. There was moderate to marked congestion of hepatic sinusoids and portal vessels with multifocal, randomly arranged aggregates of macrophages laden with coarse granules that had positive results when stained with Prussian blue dye (hemosiderin). Hepatocytes contained a fine dusting of similar granules within their cytoplasm.
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GE Vivid 7 Dimension 10s multifrequency transducer, GE Healthcare, Fairfield, Conn.