Abstract

An abnormal mass was diagnosed in the genital area of two female Tursiops truncatus. Because of the likelihood of a viral infection and the possibility of the contagious spread of the disorder, a surgical biopsy was ordered for differential diagnosis. Due to the advanced state of husbandry training of the animals, voluntary behavioral control was selected over physical restraint for conducting the biopsy, and resulted in successful procedures in both cases. After application of lidocaine spray on the vaginal mucosa, followed by peri-lesional injections of lidocaine 4 percent, three biopsy samples were taken using 4-mm biopsy punches. Bleeding was quite reduced by applying locally Yunnan Baiyio powder after having given it PO the morning of the biopsy. Bleeding stopped after 30 minutes in one animal and 10 minutes in the other. Each sample was divided and either kept on dry ice or in a 10 percent formalin solution for further processing. The histopathology results revealed focal to severe diffuse epithelial hyperplasia, with pseudocarcinomatous rete ridges in one animal; infiltration of neutrophils and lymphocytes in the propria right under the epithelium; moderate to severe intracellular edema; and epithelial cells with amphophilic homogeneous staining nuclei (suggestive of papillomavirus infection) were found in the stratum basale. Immunohistochemistry using a polyclonal antibody derived from bovine papillomavirus type 1 (BPV-1) was used and was positive for both animals. At the time of this abstract, the biopsy sample of the first animal was positive for papillomavirus structural virus proteins using a cocktail of sera from rabbits immunized with canine oral papillomavirus virions, human papillomavirus type 8 virus-like particles and bovine papillomavirus type 1 virions. The sample was negative for human papillomavirus types as determined by in situ hybridization. Viral antigens were present in high concentration right up to the upper layers of the epithelium in the first animal, meaning that the lesion was highly infectious at the time of the biopsy. Presently cutaneous forms of papillomavirus have been identified in several delphinids, including the Atlantic white-sided, the common and the bottlenose dolphin species, as well as in porpoises and killer whales. The genital form has been reported in the Dusky dolphin and the Burmeister porpoise. There isn't any proven treatment available for papillomavirus in marine mammals and until now it was thought not to be a big issue, since the lesions are usually self-limiting and would eventually regress spontaneously. However, in humans, papillomavirus infections are known to have a malignant potential towards squamous cell carcinoma. The presence of a pseudocarcinomatous propriety in one of the female should make us aware of this possibility in marine mammals, as well. The lesion has been present in this particular dolphin for at least eight years, whereas it seems to have appeared in the last two years for the other one. Possible transmission of the virus from the genital area to a calf's oral cavity during birth should also be considered; similar transmission has been postulated in humans. At this time, we have decided to tentatively histo-freeze the remaining lesions (the lesion in animal with the most recent lesion, has nearly completely regressed after the biopsy) and to further test the male population.