Renal Disease in Captive Frogs: A Retrospective Study of Amphibian Histopathology
American Association of Zoo Veterinarians Conference 2008
Lisa M. Mangus1; Richard J. Montali2, DVM, DACVP, DACZM; Leigh Ann Clayton3, DVM, DABPV; Ellen Bronson4, Vet Med, DACZM
1College of Veterinary Medicine, The Ohio State University, Columbus, OH, USA; 2Department of Molecular and Comparative Pathobiology, Johns Hopkins University, Baltimore, MD, USA; 3National Aquarium in Baltimore, Baltimore, MD, USA; 4Maryland Zoo in Baltimore, Baltimore, MD, USA
Pathology reports from Johns Hopkins University’s veterinary pathology database were examined to determine the prevalence and types of kidney disease in amphibians. The submitted amphibian cases originated from in-house laboratory animal research facilities, the National Aquarium in Baltimore (NAIB) and the Maryland Zoo in Baltimore (MZIB). Kidney lesions were present in 150 of 408 (36.8%) cases in the database. Anurans with renal disease from NAIB and MZIB were examined in more detail. This subset was comprised of multiple frog species from NAIB submitted in 2006 and 2007 (26 cases) and Panamanian golden frogs (Atelopus zeteki) from MZIB submitted from 2001 to 2007 (37 cases). Within this subset of 63 cases, the most common morphologic diagnosis was interstitial nephritis (42.9%), followed by mineralization (30.2%), tubular degeneration (17.5%), tubular dilation/ectasia (15.9%), protein casts (14.3%), unqualified nephritis (14.3%), and tubular cysts (11.1%). Concurrent skin disease, typically bacterial or fungal dermatitis, was present in 49.2% of animals. Correlation of antemortem findings with histology findings showed 15 animals (25.4%) to have edema/hydrocoelom. Twelve of these 15 frogs (80%) had tubular dilation or degeneration. Among the frogs that showed mineralization in the kidneys, 26.3% were reported to have experienced hind limb paralysis/paresis. No clinical correlations could be drawn in regard to the occurrence of tubular cysts. The pathogeneses of these histopathologic findings are currently not well understood and further investigation into the role of renal disease in amphibian mortality and morbidity is warranted.