Ringworm is not a worm at all, but a fungus. It can affect dogs, cats, horses, guinea pigs and people. There are several species of this fungus. Some can be found in the soil and other species have adapted to live solely on animals. Some species can be transmitted from pets to people or from people to pets.

The fungus “lives” on the surface of the skin, inside the hair shafts and around nail beds. A classic lesion in a pet is a rapidly expanding circular patch on the skin with hair loss and redness. Some animals can carry the fungus without showing any signs at all. Diagnosis is made by fungal culture. This is a simple test to actually perform, but may take up to three weeks to get results.

Treatment for ringworm consists of medicated shampoos, dips, clipping hair coats, topical medications and/or oral medications. The fungus can survive in the environment for a long time, so cleaning the household is important. Pet brushes, combs and pet bedding should be thoroughly disinfected with dilute bleach or even replaced. Vacuuming daily, including furniture, should be done and the bag disposed of each time. Professional cleaning of household ductwork may be needed in extreme cases.

Some people, especially children or those with other illnesses can be at increased risk to the fungus. Anyone handling pets with ringworm should wash their hands well using dilute betadine solution or iodine soap. Their human medical professional should also be consulted.

The prognosis for pets with ringworm is usually good. Few pets can remain as carriers and continuously expose other pets and people to the fungus.