Javier G. Nevarez1, DVM, PhD, DACZM, DECZM (Herpetology); Wes Baumgartner2, DVM, PhD, DACVP; Fabio Del Piero3, DVM, PhD, DACVP; Peter L.H. Jowett4, PhD
1Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA; 2Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Starkville, MS, USA; 3Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA; 4Louisiana Animal Disease Diagnostic Laboratory, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
Since 2009, an increased number of liver pathology cases in captive reared alligators has been observed. Common gross findings include icterus (skin, sclera, mucus membranes, and greater vessels) with a nodular and fibrotic liver. Histopathologic evaluation of one case revealed diffused marked periportal and bridging hepatic fibrosis, biliary hyperplasia, and oval cell hyperplasia affecting up to 90% of the liver parenchyma. A second case revealed approximately 90% of the hepatic tissue was effaced and replaced by hyperplastic biliary ducts and edematous loose connective tissue with numerous heterophils, moderate numbers of lymphocytes and plasma cells, and multifocal hemorrhage. Portal areas were moderately expanded by fibrous and loose connective tissue and frequently seen severely thickened vessel walls by fibrosis. In both cases, liver tissue tested positive for aflatoxin M1.
The animals in the first case were identified as part of an ongoing alligator health surveillance program with the Louisiana Department of Wildlife and Fisheries. These animals were originally from the state of Georgia and part of the diet consisted of whole chickens. Those in the second case were identified at the time of slaughter. These animals were fed a commercial pelleted diet only. Due to the high turn around time of feed, we were unable to sample feed used before the diagnosis to confirm the presence of aflatoxins in the diet. One farmer did report problems with high humidity in the silo used for storing the feed. Feeding practices and feed storage are believed to be associated with the occurrence of disease.
We thank the Louisiana Department of Wildlife and Fisheries and the United States Animal, Plant, and Health Inspection Services. We would also like to thank Dr. Michael Garner for his guidance and assistance in the early diagnosis of cases.