Multifocal Ophidiomyces ophiodiicola Infection in an Eastern Diamondback Rattlesnake (Crotalus adamanteus) without the Presence of Skin Lesions
A 15-yr-old captive-born male Eastern diamondback rattlesnake (Crotalus adamanteus) presented for the presence of two slow-growing subcutaneous/intramuscular masses along the dorsum. Whole-body radiographs showed two subcutaneous soft tissue masses and two soft tissue opacities within the lungs. An initial punch biopsy of one of the subcutaneous masses revealed chronic granulomatous cellulitis with intralesional fungal hyphae. During a follow-up examination, repeat biopsy of one of the subcutaneous masses confirmed Ophidiomyces ophiodiicola, the causative agent of snake fungal disease, via quantitative polymerase chain reaction (qPCR) of fresh tissue. Additionally, cytology of one of the intracoelomic masses obtained via fine needle aspirate showed evidence of necrosis with fungal hyphae consistent with O. ophiodiicola. Given the multiorgan nature of this disease at the time of diagnosis, and the concern for a lack of therapeutic efficacy, the snake was euthanized. Antemortem cytology, histopathology, and necropsy revealed fungal hyphae in multiple subcutaneous/intramuscular and pulmonary granulomas that were consistent with an O. ophiodiicola infection without the presence of skin or labial pit lesions. To the authors' knowledge, this is the first report of multifocal O. ophiodiicola (snake fungal disease) infection in a crotalid without skin crusts, ulcers, or scabs present.Abstract
Representative photomicrographs of one of the subcutaneous granulomas. (A) Fungal granuloma in the skeletal muscle of an Eastern diamondback rattlesnake with an inner core of abundant degranulated and necrotic heterophils (asterisk), rare fungal hyphae (arrow), and an outer wall of plump macrophages (star). Hematoxylin and eosin stain. Bar = 50 μm. (B) Necrotic core of a fungal granuloma containing few 3–6-μm-wide, septate fungal hyphae with occasional branching. Gomori's methenamine silver stain. Bar = 25 μm.
Right lateral radiographic image of the cranial third of the Eastern diamondback (Crotalus adamanteus). There are two, round, soft tissue opacity masses (*) present in the cranial coelom consistent with masses in the lung. Two additional soft tissue masses are outlined with barium sulfate contrast (white arrows) within the subcutaneous space of the snake.
Gross necropsy image of the lung showing two (3 × 2.5 × 1 cm and 2 × 1.5 cm diameter), firm, well-demarcated, pale red masses that bulge from the surface of the lung (*). The masses have prominent vasculature on the pleural surface. Bar = 1 cm.
