The term "ringworm" is misleading. The disease has nothing to do with a worm but is actually a common infection of skin, hair, and nails that is caused by one of several different types of fungus. Ringworm, which is also called dermatophytosis, typically affects kittens, but cats and dogs of any age and other animals, including people, can be infected. Ringworm is contagious, so animals undergoing treatment should be isolated, and owners should wear gloves and wash their skin and clothes thoroughly after handling an infected pet.
Symptoms of ringworm include hair loss, itching, flaky or crusty skin, and/or misshapen and brittle nails. A veterinarian may suspect ringworm after a complete history and physical exam, but additional tests like plucking hairs and attempting to culture (i.e., grow) and identify the fungus or skin biopsies are necessary to differentiate the disease from other conditions that cause similar clinical signs. If multiple animals live in close contact with one another, it is not uncommon for several individuals to be infected with ringworm, even if they are not all symptomatic.
Medicated baths and dips and topical and oral anti-fungal drugs are used to treat ringworm. In some cases, shaving an animal with a long coat can speed healing and reduce the chances of it spreading ringworm to other animals or people with which it has contact. Treatment for ringworm generally needs to continue for several months and should not be stopped until follow-up cultures are negative. Animals can become reinfected immediately after treatment stops, so vacuuming and disinfecting a pet's environment is also very important.
Written by: Jennifer Coates, DVM
Last reviewed: October 2, 2008