(425) 742‑0342

16429 7th Place West
Lynnwood, WA 98037

hero image

Animal Skin and Allergy Clinic Blog

Getting Rid of Ringworm and Other Fungal Infections in Pets

A dog with skin conditions

Fungal infections in pets are no fun. There are a variety of fungal organisms that can cause problems for our four-legged friends. Read on to learn about fungal infections in pets and how we can combat them.

Yeast Dermatitis

Yeast, which is a common fungus, is a frequent offender when it comes to skin and ear infections. Pets who have an overgrowth of yeast organisms on the skin are often itchy, scaly, and smelly. If the infection is long-standing they may even develop a characteristic thickened, elephant-like appearance to the skin.

Yeast organisms live on the skin all the time, but may grow out of control under extenuating circumstances. Any condition where there is increased oil production, such as an allergic flare-up, can lead to a yeast overgrowth. The most frequent yeast organism that lives on the skin of our pets is Malassezia.

We can identify a yeast fungal infection in pets by taking samples from the skin and analyzing under the microscope. If a yeast overgrowth is identified, it is often treated by:

  • Addressing the cause of increased oil production
  • Using topical treatments, such as shampoos or ointments
  • Prescribing oral antifungals, when needed


A black dog with ringwormRingworm, despite a deceiving name, is neither a worm nor does it necessarily grow in a ring. This skin infection is caused by a group of fungi referred to as dermatophytes. In people, they typically result in a round, red lesion with a scaly ring around the edges. In our pets, they more commonly present as a scaly, dry patch, but can look like a variety of other skin conditions.

Dermatophytes produce spores that live in the environment and one, the cat dermatophyte called Microsporum canis, can be extremely difficult to treat. Some cats may even be infected without visible signs, meaning that they contaminate their surroundings with fungal spores even though they aren’t showing signs of infection.

If ringworm is suspected, we will often take samples from the hairs and incubate these on a culture plate. This can help us to confirm a suspected infection and identify what type of dermatophyte we are dealing with. Sometimes skin biopsies may need to be performed to achieve a diagnosis.

Depending on the type and severity of the ringworm infection, several treatments may be recommended. These can include one or more of the following:

  • Topical antifungal creams
  • Antifungal dips or shampoos
  • Shaving
  • Systemic antifungal medications
  • Environmental treatment

Is it Ringworm, or is it Not?

A black and white boxer with a skin condition

Ringworm is a condition that causes inflammation of the hair follicles. There are two other infections that also attack the hair follicles, Demodex mites and bacterial infections, and all are grouped under a condition known as folliculitis. All of them look the same since they all affect the hair follicle.
These 3 photos show different dogs with different diseases: one with ringworm, one with Demodex mites, and the last with a bacterial infection. All are diseases that affect the hair follicles and are indistinguishable from each other to the casual, and most times even to a trained, observer. The cause can only be determined by using correct diagnostic procedures, all of which can be done in the veterinary hospital during an examination. Veterinary dermatologists are specially trained to know how, and when, to perform and interpret these tests.

Other Fungal Infections in Pets

There are several less common fungal infections in pets that can affect the skin. Most of these are systemic types of infections that affect other body systems as well. Systemic fungal infections, such as blastomycosis and Valley Fever, are usually quite serious and require intensive treatment.

Fungal infections in pets are quite common. Luckily, most are dealt with fairly easily. If your pet is diagnosed with a fungal infection, never fear. The Animal Skin and Allergy Clinic is here to help!