Importance of Differentiating Fungal Species when Diagnosing Dermatophytosis

Valerie Fadok, DVM, PhD, DACVD, dermatologist in the Veterinary Specialty Team at Zoetis, explains the importance of knowing which species caused dermatophytosis in your pet.

Interview Transcript (slightly modified for readability)

“In my opinion, it is very important to know which fungus causes the dermatophyte. While in many parts of the country and the world [Microsporum] canis is the most common cause, in some parts, the prevalence of, say, [Microsporum] gypseum might be higher, or Trichophyton species. The reason it’s important to know the species, is the species will dictate how aggressive we have to be with therapy.

As an example, I have a kitten in a home with two adult cats, a dog, two children, and a mom, and people start breaking out with lesions, we have to be very aggressive about treatment [for] M. canis. We need to use systemic anti-fungal therapy, we need to use topicals, and we need to do some environmental clean-up.

By contrast, if we have, say, a Jack Russell who’s been rooting around in the soil, and they get M. gypseum, [which] is a soil fungus, it’s not contagious from animal-to-animal, or animal-to-people. It’s much more easy to treat; we can get a topical, [or] we can use a systemic. We don’t treat the environment because we can’t sterilize the soil. I think knowing the species determine how aggressive we have to be with treatment, and that comes back to [if] the client [can] comply, and how expensive it’s going to be. To me, there’s the value in knowing the species.”