Ringworm Infection in Dogs and Cats

Ringworm in Dogs and Cats

            Ringworm is not actually caused by a worm as the name suggests but rather it is a skin infection caused by several species of fungus that can infect dogs, cats and people as well as large animals such as cattle and horses.  Ringworm can be transmitted by direct contact with infected animals or people, through contact with contaminated surfaces especially soft surfaces such as bedding or furniture and the fungus can also be found in soil and infection can spread by contact with infected soil when doing activities such as gardening. 

            Ringworm typically causes circular, crusted areas of hair loss on the skin and the lesions may be itchy.  The condition is best diagnosed by a fungal culture—a few hairs are plucked from a lesion and placed on a gel plate that will change color from yellow to red within 7-10 days if fungal organisms are present.  A special type of black light called a Wood’s Lamp may also be used to diagnose some species of ringworm fungus or dermatophytes.  Certain species glow a bright apple green under the light.  Once in a while, cats may be carriers of the fungus, but not show any outward clinical signs. 

            Ringworm can be treated in several ways.  If there are only a few localized lesions, a topical antifungal cream may be applied daily for several weeks to the affected areas.  If the lesions are covering large areas of the body, anti-fungal shampoos and/or antifungal pills may be used to treat the patient.  Because it is contagious, all household pets may need to be treated and special decontamination of the house and environment may be necessary. Unaffected pets in a multi-pet household may need to be isolated from those affected and receiving treatment.  Remember, ringworm is caused by fungus, not bacteria. Antibiotics are ineffective.

            Ringworm may be extremely difficult to treat in a shelter or breeding facility, but it is typically manageable in a home situation. Pets may need to be treated for up to eight weeks and anyone handling affected pets should use good hygiene when handling affected pets.  Wash your hands after handling pets with ringworm and do not sleep with or cuddle infected cats or dogs. Immune compromised individuals should not handle pets with ringworm.  Pets should have a fungal culture repeated at the end of the course of treatment to ensure the infection is resolved.

With proper treatment, most ringworm infections will resolve, but treating pets in a multi-pet household or shelter may be challenging.

            This blog brought to you by the Patton Veterinary Hospital serving Red Lion, York and the surrounding communities.