Two of the most common fungal infections in cats and dogs

In this interview, Domenico Santoro, DVM, MS, DRSC, PhD, associate professor at the University of Florida College of Veterinary Medicine, and service chief of dermatology in the school’s Small Animal Clinical Sciences department, discusses common fungal infections in dogs and cats as part of a discussion on his lecture Fungus Among Us: Fungal Skin Infections in Dogs & Cats, which was presented at the 2025 WVC Annual Conference in Las Vegas, Nevada.

As Santoro explains, Malassezia pachydermatis is one of the most prevalent fungal infections in cats and dogs. This yeast infection, according to Santoro, is primarily associated with secondary infections in animals with allergies. However, it can also be linked to other primary conditions. Santoro also talks about dermatophytes, commonly known as ringworm, which represent another common fungal infection in feline and canine patients.

Below is the interview transcript, which has been lightly edited for clarity:

Domenico Santoro, DVM, MS, DRSC, PhD: My name is Domenico Santoro. I'm an associate professor in dermatology at the University of Florida. I have a PhD in immunology, and I'm service chief of the dermatology service here.

The most common fungal infection that we see in dogs and cats is actually due to yeast, due to Malassezia pachydermatis. That's a common commensal of the skin of dogs and cats and is mainly associated [with] a secondary infection in dogs and cats with allergies, but also other primary diseases like endocrinopathy or tumors—cancers.

[Following] that, the other common fungal infection is due to dermatophytes. So those are like superficial fungal infections. The late term for these would be ringworm, so they're more [commonly] known as ringworm [by] the general population, and they're less common than what is generally taught, but can be definitely present in dogs and cats, specifically in young animals or older animals or sick animals or animals coming from shelters in which...their immune system is not properly developed or is [weakened] because of comorbidities. So those animals are more prone to getting this type of infection.