Ulcerative skin lesions were observed in three captive adult female hippopotamus (Hippopotamus amphibius) held in two North American institutions. Lesions appeared as cracking, peeling, or vesicles of the skin affecting the lateral and ventral aspects of the neck, limbs, thorax, and abdomen, dorsum, toes, and around the perineal region. Lesions progressed to tissue sloughing of variable severity, ranging from superficial, raw erythemic areas to deep, ulcerative lesions that drained blood, serum, or purulent material. While lesion appearance was similar to previously reported dermatitis in captive hippopotamus attributed to a group-G beta-hemolytic Streptococcus sp.,1 no predominant pathogens were identified in the hippopotamus from this report. Histologic evaluation of sloughed skin consisted of deep dermal collagen with bacterial cellulitis and vasculitis and superficial fungal colonization or ulcerative dermatitis with infarct and extensive colonization by bacterial and fungi. No viral pathogens were isolated and PCR testing for herpesvirus was negative. Lethargy, depression, lameness, and weight loss of variable severity were observed in all affected hippopotamus. Minimal response to previously described systemic antibiotics and topical treatment1 was observed in the hippopotamus from this report. Commercial cattle food-grade salt was added to the exhibit pool of both facilities at 2–3 parts per thousand with a positive response to salt bath therapy observed in all affected hippopotamus over a 4–6-month treatment period. Seasonal recurrence of similar skin lesions was noted in all hippopotamus from this report. Seasonal recurrence of dermatitis has been previously observed in captive hippopotamus with similar lesions (V. Clyde, personal communication).
The authors would like to thank Dr. Jim Wellehan at the University of Florida for performing the herpesvirus PCR; Dr. Vickie Clyde and Dr. Roberta Wallace of the Milwaukee County Zoo for their consultation and expertise; and the hippopotamus care staff of the Woodland Park Zoo and Birmingham Zoo for their dedication and daily care of the patients in this report.
1. Clyde, V.L., R.S. Wallace, and A.N. Pocknell. 1998. Dermatitis caused by group B beta-hemolytic Streptococcus in Nile hippos (Hippopotamus amphibius). Proc. Am. Assoc. Zoo Vet. Pp. 221–224.