Microsporum canis infection, coloured environmental scanning electron micrograph (ESEM). The thread-like structures (green) are hyphae, the vegetative part of the fungus. Microsporum canis is a dermatophyte fungus, one that infects keratinized tissues (skin, nails, hair) in humans and other animals. These fungal infections are known as ringworm. This fungus, normally found on cats and dogs, can also infect humans, especially children.