Because ringworm is infectious, animals with the disease should be quarantined within the owner's home until the disorder can be cured. All infected animals or asymptomatic carriers within the household should receive topical therapy, which may include clipping down the hair and applying an antifungal ointment to the skin or shampooing and dipping the entire dog or cat in medicated products. The examining veterinarian will recommend the best approach depending on the location of the lesions. Topical treatment is continued until a negative fungal culture is obtained.
Animals that do not appear to respond to topical treatment within two to four weeks may be given supplemental oral drug treatment in order to eradicate the infection more quickly. The most commonly used oral antifungal medication is griseofulvin, but some fungal infections may be resistant to it. Also, some animals, especially cats, cannot tolerate griseofulvin and may develop a serious side effect of fatal bone marrow suppression. Thus, serial complete blood count tests are performed on cats taking this drug to watch for evidence of bone marrow problems. Also, cats with the feline immunodeficiency virus should not be given this drug. Ketoconazole and itraconazole, two drugs that are not licensed currently in the United States for the treatment of ringworm, nevertheless are used effectively as an alternative to griseofulvin for animals that cannot tolerate this medication. Typically, griseofulvin is safe for dogs.
A vaccination against Microsporum canis has been developed for cats, but the safety and efficacy of this vaccination still needs to be researched. The use of the vaccine may be recommended in frustrating cases of ringworm infection.
Infections can be very difficult to eradicate in multiple-cat households or breeding facilities and often require the consultation of a veterinary dermatologist. Humans should wear gloves while treating the infected animal and follow the recommended protocol for avoiding infection, including a thorough disinfection of the indoor environment. If human infection does occur, prompt medical attention is advised.
