Ringworm in Dogs & Cats
Ringworm is the common term for fungal infections in the skin, caused by types of fungi called Dermatophytes. The disease has nothing to do with worms but is usually characterized by ring-like hairless or inflamed areas on the animal’s coat.
Ringworm lesions can mimic many other skin conditions. Sometimes a blue-light used by the veterinarian can be helpful. A negative result is meaningless since only certain types of ringworm “light up” but a positive result can be diagnostic.Ringworm cultures can be done from hairs but take up to 2 weeks for results and again, false negatives are possible. At times, response to therapy can be the most diagnostic approach. Some animals can be carrier animals, having fungal organisms in their coat but not showing symptoms. Therefore when treating ringworm, all animals must be treated. Infections are transmitted by contact with infected hairs, either on the pet or those falling off into the environment. Therefore, not only all pets, but also the environment must be treated. Although ringworm can be contagious to people, it is rarely a serious problem. If you do develop lesions, consult your physician.
Treatment is continued a minimum of 2 weeks past cure (at least 4 weeks) and can include the following options:
- Clipping the hair away form the lesion(s) or even the entire body if lesions are diffuse, can be helpful in slowing spread of the fungus and allowing more effective topical therapy.
- With small isolated lesions a topical antifungal cream can be helpful. It should be applied to the lesion and out into surrounding normal skin. It is usually best to combine this treatment with some kind of whole body shampoo or dip.
- Shampoo therapy is safe and may help to reduce or eliminate organisms from the coat. Shampoo therapy is rarely curative by itself in active infections. Ketoconazole (Nizoral) Shampoo or Chlorhexiderm (Nolvasan) Shampoo can be used every 5-7 days.
- Lym-Dyp is a very safe and effective treatment option. Follow directions carefully. The dip is diluted out and sponged into the pets coat , soaking to the skin every 5-7 days. The dip is not rinsed off. The problem with Lym-Dyp is that it smells like rotten eggs and will stain everything it contacts. It is best to remove all jewelry, wear gloves and use a plastic tub that can be disposed of after your pet is cured. Work outdoors if at all possible.
- Griseofulvin is a tablet that is given 1-2 times daily. It is highly effective and may be the treatment of choice, especially in severe cases or when Lym-Dyp is not practical. However, although uncommon, Griseofulvin can be toxic and in rare cases cause severe problems. It cannot be given to pregnant animals and may cause side effects including Gastrointestinal upset, bone marrow suppression and liver toxicity. Bloodwork should be monitored when pets are taking this medication and costs will increase concurrently.
- The environment must be thoroughly cleaned, including vacuuming, change filters in air conditioning units, dusting and wherever possible using hot water and detergent with 1:10 Clorox bleach to wash bedding materials, etc. In severe cases it may be necessary to steam clean carpeting using 1 oz. Nolvasan / gallon. When possible, attempt to quarantine affected animals to one room of the house and minimize traffic from this area to reduce environmental contamination.