CHOLELITHIASIS IN CAPTIVE MOUNTAIN CHICKEN FROGS (LEPTODACTYLUS FALLAX): DIAGNOSTIC IMAGING AND HISTOPATHOLOGICAL FEATURES

The mountain chicken frog (Leptodactylus fallax) is a critically endangered species highly reliant on ex situ conservation programs. In captivity, cholelithiasis has been reported during clinical examinations using diagnostic imaging and observed during postmortem examinations. Some individuals have presented with nonspecific clinical signs potentially associated with this condition, but little is known about its clinical relevance. A retrospective evaluation of ultrasonographic (n = 139) and radiographic (n = 156) images and histopathology samples (n = 32) obtained between 2014 and 2020 from 133 individuals was performed. An ultrasound scoring system was developed to evaluate changes in the gallbladder, with 38% (53/139) of the images showing abnormal contents. Gallbladder distension appeared associated with these findings (generalized estimating equation model, P < 0.001). In contrast, radiography proved to have low overall sensitivity (48%) when compared to ultrasonography for identifying abnormal gallbladder contents. A weak level of agreement (Cohen's kappa = 0.535) was observed between the imaging modalities. Histologically, cholecystitis was present in 86% (12/14) of the individuals, thickening of the gallbladder wall in 71% (10/14), and intrahepatic cholangitis in 90% (18/20). There was no evidence of cholestasis in any of the affected individuals. A significant difference was observed in the hepatic melanomacrophage density between animals with and without cholelithiasis (Welch two-sample t test, P < 0.001). This study provides an overview on the use of diagnostic imaging modalities to evaluate cholelithiasis and proposes a convenient ultrasound score to standardize monitoring of the condition in L. fallax. It is also the first systematic review of histopathological changes associated with cholelithiasis in this species.