"The dermatophytes" are a group of three genera of taxonomically related filamentous fungi. The three genera are Microsporum (observe primarily macroconidia), Trichophyton (observe primarily microconidia), and Epidermophyton (observe distinctive smooth-walled macroconidia in clusters of 2 or 3).

Microsporum canis produce large, multicellular (5-8 cells per conidium), thick- and rough-walled (echinulate) macroconidia. Some macroconidia may be fusiform.  Rare microconidia are small and clavate (club shaped).