Multifocal hyperemic nodules and plaques associated with the cloacal mucosa of juvenile alligators (Alligator mississippiensis) at a public aquarium were investigated. All of the affected animals were obtained from the same distributor and housed together in an indoor exhibit. Blood work and the cloacal mucosa of 15 juvenile alligators (11 female, 4 male) were examined. Hematology and clinical chemistries were within normal limits.2 Grossly, pale pink to dark red multifocal, circular lesions of varying degrees of severity were identified on the cloacal, and in males, phallus mucosa. Other clinical signs were not apparent. No parasites were visualized on fecal flotation of random feces obtained from the enclosure. Fecal cytology revealed a small number of budding organisms consistent with yeast.
Cloacal mucosa biopsies were obtained from two of the alligators. These samples were examined histologically, and by polymerase chain reaction (PCR) using probes for herpesvirus and iridovirus. Microscopically, the lesions were characterized as submucosal lymphoid follicles with hyperemia and hemorrhage. The nodules were composed of aggregates of round cells located within the superficial dermis. Minimal to no anisokaryosis and no etiologic agents were identified. Through PCR, a band consistent in size with herpesvirus was identified. Sequencing of the PCR product is currently being pursued to characterize the virus further.
In the United States, intensive captive breeding of alligators is performed for commercial and exhibit purposes. Diseases with potential for sexual transmission could complicate captive breeding, and further transmission and long-term effect studies should be investigated. Viruses known to infect crocodilians include parapoxvirus, adenovirus, paramyxovirus, eastern equine encephalitis virus (EEE), influenza C virus, West Nile virus and coronavirus. Of these, paramyxovirus and EEE have not been associated with clinical signs, and none are known to cause genital lesions.1 Herpesvirus has never been reported in crocodilians.
The authors wish to thank Hap Fatzinger, Elliot Jacobson, Keith Linder, Talmage Brown, and Steve Rushton for their contributions.
1. Huchzermeyer FW. 2003. Viral Infections. In: Huchzermeyer, F.W (ed.) Crocodiles: Biology, Husbandry, and Diseases. CABI Publishing, Cambridge, Massachusetts. Pp. 157-163.
2. International Species Information System (ISIS). 1998. Physiologic Reference Values Compact Disc. 12101 Johnny Cake Ridge Road. Apple Valley, MN 55124-8151.