Two cases of dermatophytic pseudomycetoma in the dog: an immunohistochemical study

Two cases of canine dermatophytic pseudomycetoma resulting in subcutaneous nodules resembling those previously reported in Persian cats are described. Culture performed from one nodule yielded dark yellow colonies consistent with Microsporum canis. Immunohistochemistry, using rabbit anti-M. canis, d emonstrated specific binding to fungal elements in paraffin sections. The s pecificity of the antiserum was further tested by an agar gel immunodiffusi on assay using a soluble extract from a feline isolate of M. canis as antig en. The antiserum did not cross-react with an Aspergillus fumigatus antigen . These are the first two reported cases of canine dermatophytic pseudomyce toma and immunohistochemical staining supported the diagnosis.