Ringworm (dermatophytosis) is a clinical condition caused by fungal infection of the skin in humans, companion animals such as cats, and domesticated animals such as sheep and cattle. It is caused by fungi of several different species. The fungi that cause parasitic infection (dermatophytes) feed on keratin, the material found in the outer layer of skin, hair, and nails. These fungi thrive on skin that is warm and moist, but may also survive directly on the outsides of hair shafts, or in their interiors. In pets, the fungi responsible for the disease survive in skin and on the outer surface of hairs.
