Treatment of Canine and Feline Dermatophytosis

Valerie Fadok, DVM, PhD, DACVD, dermatologist in the Veterinary Specialty Team at Zoetis, discusses the principles of treating dermatophytosis.

Interview Transcript (slightly modified for readability)

“[The] basic principles of treating dermatophytosis are the same. We have the option of using a systemic drug, we have the option of using a topical medication, and we have environmental treatment. One of the things that [is] relatively new is the progression of the availability of systemic drugs for cats and dogs. In the old days, we always used griseofulvin, [which] is a great drug, but cats can be sensitive to the side effects; now, we have these wonderful azole drugs. Itraconazole became the drug of choice for [treating] cats, [but] it’s quite expensive. People were getting it compounded, and we learned that the compounded material is not equivalent. So, because of cost, many of us are using a drug called terbinafine, now, [which] is the generic name of Lamisil. It used to be very expensive, but now, it’s the most economical choice, and we have papers to verify its use in both cats and dogs.

[As for] topical therapies, for years, in the United States, we relied on lime sulfur, and we still do. But [for] a cat that has to have a lime sulfur dip, it’s very unpleasant, so people are exploring other topicals. There’s a shampoo concentrate called accelerated hydrogen peroxide, [which] is much less noxious. The use of shampoos that contain antifungal ingredients, [as well as] foams and sprays, [are] things that [make it] easier for the client to apply to their pet, whether it’s a dog or cat.

Doctor Karen Moriello, who I think of as the goddess of dermatophytes in veterinary medicine, [has] done a series of studies to show which household cleaners will kill ringworm spores in the home. We always used to say you have to use 1-10 [percent] bleach, but [this] is very, very concentrated, and will destroy fabric, and a lot of finishes on your furniture. Now, she has come up with a list of home cleaners, some of which are not bleach-based, that we know will kill ringworm spores. I think it’s made it much easier for the client to move forward with some of these environmental treatments that we recommend.”