Epidemic nodular facial myxomatous dermatitis in juvenile Cranwell’s horned frogs Ceratophrys cranwelli

Abstract

In 2017, approximately 40 out of 100 captive Cranwell’s horned frogs Ceratophrys cranwelli from several facilities in Japan exhibited protruding facial lesions. Histopathological examination was performed on 6 specimens with such lesions randomly selected from 2 facilities. Lesions consisted of scattered stellate to spindle-shaped cells without atypia in an abundant myxoid matrix and occasional lymphocytic infiltrates. Maxillary bone was resorbed. No etiological organisms were detected using light microscopy or metagenomic analysis of the lesions. Macroscopic and histological assessments indicate that the lesions are associated with nodular facial myxomatous dermatitis, which has never been reported in amphibians.