Nodular and neoplastic skin lesions in an aquarium-managed group of Sabana Surinam toads Pipa parva

Abstract

Although skin disease is a common cause of morbidity and mortality in amphibians, published reports of integumentary conditions affecting skin-brooding anurans are extremely limited. This case series describes the clinical, macroscopic, and histopathologic features of nodular skin lesions in an aquarium-managed population of Sabana Surinam toads Pipa parva, a fully aquatic, skin-brooding species native to South America. The skin lesions represented an ongoing clinical concern in this group, affecting approximately 10-20% of animals throughout the study period, and were observed exclusively in females, suggesting an association with the females’ specialized cutaneous reproductive anatomy. Multiple animals died or were euthanized due to skin lesions, which were histologically complex and encompassed a range of hyperplastic, cystic, and neoplastic changes (with internal metastases in one animal). Cultures and special stains showed evidence of mixed polymicrobial infection, including occasional fungal hyphae and acid-fast organisms, but were predominated by Gram-negative bacteria. Lack of a significant response to various environmental modulations and therapeutic interventions indicates that the pathogenesis of the skin lesions is multifactorial. Additional research into the reproductive physiology and ideal environmental conditions (both social and physical) for this species will likely help identify new strategies for prevention and treatment of skin disease.