Abstract

An adult male Beluga whale (Delphinapterus leucas leucas) presented with a 4 cm diameter raised firm papule on the ventral aspect of the left pectoral fin. Initial treatment with cephalexin (25 mg/kg PO BID x 10d) and topical application of silver sulfadiazine twice daily resulted in minimal change. The papule cracked and exfoliated developing into a large collarette with a friable, raised border. Initial diagnostics were suggestive of an epithelial inclusion cyst with no apparent infectious etiology. After 1 month, the lesion rapidly progressed to a 24 x 8 cm roughly oval lesion with irregular, yellow, friable margins surrounding a flat, roughened surface. Biopsy revealed proliferative lymphocytic and suppurative dermatitis with intralesional fungi; identified by PCR as Fusarium solani. Fungal sensitivity testing revealed resistance to single and combination drug regimes.

Treatments employed included serial surgical debridement of affected and surrounding tissue, topical application and regional infusion of antifungals combined with dimethyl sulfoxide (DMSO) or Tricide®. The lesion continued to progress to 36 x 25 cm extending from the axilla to the fin's dorsal surface. After 6 weeks under treatment with voriconazole (3 mg/kg PO BID x 10d; 3 mg/kg PO q7d x 4 doses) the lesion began to improve. Voriconazole dosage was tapered based on serum levels. Fourteen months after initial presentation, treatment continues with a protocol of voriconazole (1.96 mg/kg PO q14d), terbinafine and DMSO (TO q7d), with no dermal irregularities visible.

Acknowledgments

The authors wish to thank the Animal Health and the Marine Mammal Departments at the John G. Shedd Aquarium for their hard work and dedication, Dr. Michael Rinaldi, Dr. Sylvain De Guise, and Dr. Hendrick Nollens for their assistance, expertise and time with this challenging case.