Cutaneous botryomycosis in a free-living short-beaked echidna (Tachyglossus aculeatus).

Botryomycosis is a chronic bacterial infection of the skin and viscera caused by nonbranching bacteria such as Staphylococcus spp. It results in the formation of chronic, suppurative and often granulomatous lesions that may resemble multiple abscesses. It has been diagnosed worldwide in both humans and animals. It is a rare disease, usually requiring surgical excision combined with long-term antibiotics to achieve a good resolution. A wild echidna (Tachyglossus aculeatus) was presented with a soft tissue mass at the base of the right distal beak with multiple discharging fistulas arising from it. The mandible appeared to be shortened and deviated to the right, and the animal was unable to close its beak. The echidna was in poor body condition and was euthanased on welfare grounds. Histopathology of the lesions demonstrated the classical botryoid lesions with the characteristic Splendore-Hoeppli reaction surrounding the bacterial colonies, in a background of extensive granulation tissue. Radiographs revealed mild mandibular osteomyelitis, yet haematology and biochemistry results were nonspecific. This disease has not previously been reported in a wild monotreme.