Clinical observations on equine phycomycosis

During a clinical study of equine phycomycosis in tropical northern Australia 3 specific forms of phycomycosis were identified. Of 266 cases diagnosed in 5 different laboratories, hyphomycosis caused by Hyphomyces destruens was responsible for 76.7%, basidiobolomycosis caused by Basidiobolus haptosporus for 18.0%, and entomophthoramycosis caused by Conidiobolus coronatus for 5.3%. Most cases of hyphomycosis were observed between March and July, that is after the monsoonal wet summer, but were calculated from clinical histories to originate in the wet season between November and May. Basidiobolomycosis and entomophthoramycosis occurred regularly during the year and no seasonal incidence could be determined. All of these conditions occurred in horses in similar tropical regions of Queensland and the Northern Territory. No breed, sex or age predisposition was found but significant differences between the 3 fungal diseases in site of infection and appearance and size of the lesion were observed. Hyphomycosis was seen as an ulcerative granuloma containing characteristic coral-like kunkers. Lesions were most commonly found on the legs and ventral parts of the chest and abdomen, areas where contact with swamp water was apparent. Basidiobolomycosis was clinically similar to hyphomycosis but was mostly found on the lateral parts of the trunk and face where contact with contaminated soil might be expected. All lesions of entomophthoramycosis were located in the nasal region thus suggesting infection by inhalation.