Atrial septal defects in Florida panthers

Ostium secundum atrial septal defects (ASDs) were observed in six (3 M, 3 F ) of 33 (20 M, 13 F) (18%) Florida panthers (Puma concolor coryi) necropsie d by veterinary pathologists between 1985 and 1998. A seventh ASD was found in a female panther necropsied in the field and is included in the patholo gical description but not the prevalence of ASDs in Florida panthers. One p anther (FP205) with severe ASD also had tricuspid valve dysplasia (TVD). At rial septal defects and/or TVD are believed to have caused or contributed t o the deaths of three (9%) Florida panthers in this study. Mean diameter +/ - SD of ASDs was 9.0 +/- 4.7 mm (range 3 to 15 mm). Gross pathological chan ges attributed to ASDs/TVD in severely affected panthers (ASD greater than or equal to 10 mm) (n = 4) included mild right ventricular dilatation (n = 3) and hypertrophy (n = 2), mild to severe right atrial dilatation (n = 2), and acute pulmonary edema (n = 3). Panthers with mild ASDs (ASD less than or equal to 5 mm) (n = 3) had no other detectable gross pathological change s associated with the ASDs. Histological examination of lungs of three pant hers with severe ASDs revealed mild to moderate dilatation with fibrosis an d smooth muscle atrophy of the tunica media of medium to large caliber arte ries (n = 2), interstitial and/or pleural fibrosis (n = 2), perivascular fi brosis (n = 1), and acute to chronic edema (n = 3). Twenty-six necropsied p anthers were examined one or more times while living; medical records were retrospectively evaluated. Antemortem radiographic, electrocardiographic, a nd echocardiographic examinations were performed on two panthers with sever e ASDs (FP20 and FP205). Thoracic radiographic abnormalities in both includ ed right heart enlargement, and in FP205 (severe ASD and TVD), mild pulmona ry overperfusion. Electrocardiographic examination of FP205 revealed a righ t ventricular hypertrophy pattern, while FP205 had a normal electrocardiogr am. Echocardiographic examination of FP20 revealed marked right atrial dila tation; a bubble contrast study indicated regurgitation across the tricuspi d valve. Echocardiographic abnormalities in FP20 included right atrial and ventricular dilatation, atrial septal drop-out, and severe tricuspid regurg itation; non-selective angiography revealed significant left to right shunt ing across the ASD. All panthers with severe ASDs ausculted (n = 3) had sys tolic right or left-sided grade I-V/VI murmurs loudest at the heart base. A ll male panthers with ASDs (n = 3) (100%) and 9 of 17 (53%) male panthers w ithout ASDs in this study were cryptorchid.