Abstract

Pox lesions have been seen each year in the winter months on several of the dolphins housed at Marine World Africa USA. In January, 1996, a female sixteen-year-old bottle nosed dolphin (Tursiops truncatus) with a one-year-old calf, developed aberrant lesions that appeared initially as unusually large, darkly pigmented, flat "tattoo" lesions. Over a period of several weeks, the lesions enlarged, coalesced and changed in character. There were numerous large, elliptical patches measuring between 4 and 6 cm in diameter located primarily on the anterior dorsal third of her body. The lesions became raised and the overlying tissue appeared corrugated. The entire epithelial surface of the lesion sloughed, leaving large, shallow, darkly pigmented depressions. These filled in over a period of several months, ultimately leaving unpigmented patches that were otherwise as smooth as the adjoining tissue. One of the factors possibly contributing to the severity of the lesions was a high rainfall causing a low salinity, reaching a low of 19 ppt at one point.

After a year's time, the lesions on the female have re-pigmented and have almost disappeared; however, this December, fresh, very small, flat pox lesions appeared, encircling each old lesion. These fresh lesions are adjacent to, but do not cross the border of last year's lesions.

A second dolphin, male, 22 years old, and typically more prone to pox lesions than other dolphins in his area, developed similar severe lesions in December 1996, three months after the affected female was moved into his water system. The lesions on the female were completely healed when she was transported to that area. Again the salinity in December 1996 was much lower than average after many days of heavy rainfall. The lesions this male has this year are comparable to those of the female last year.