Fungi in Dogs: Symptoms, Diagnosis, and Treatment

The presence of fungi, scientifically called dermatophytes, can occur for several reasons. Immunosuppression (lowered defenses) and a humid environment are some of the most common factors behind a fungal infection in dogs.

In fact, there are several types of dermatophytes that can affect our furry friend. Let's take a detailed look at the symptoms that should put us on alert and how we should care for and treat a dog with fungi.

What Is Dermatophytosis?

Dermatophytosis is the medical term referring to a fungal infection in dogs that affects keratinized tissue (nails, skin, fur...). The most commonly isolated fungi are Microsporum canis (more commonly known as ringworm), Trichophyton mentagrophytes, and Microsporum gypseum.

They normally occur in puppies, since their immune system isn't fully developed, favoring their proliferation. For example, Malassezia is a yeast (a type of fungus) very common in dogs. It's normally found in their ears and skin.

What can happen is that, in cases of immunosuppression, it can proliferate and worsen the patient's symptoms. Under the microscope, it looks like a "footprint." Fungal lesions can occur on the snout, limbs, tail, head, groin… They usually cause a lesion called a dermatophytic kerion.

Dermatophytic kerion on the snout

Main Symptoms of Fungi in Dogs

Dermatophytosis presentations are very varied, depending on the dermatophyte causing the ringworm and the individual's response. Although fungal symptoms in dogs can vary, normally the signs that should put us on alert are:

• Hair loss in the affected areas (alopecia).
• Flaky, inflamed, or reddened skin (erythema).
• The dog may constantly lick its irritated paws, trying to soothe the discomfort it feels.
• Otitis and brownish earwax (Malassezia).
• Dermatophytic kerion (an inflamed circular lesion that can measure 1 to 4 cm in diameter and can appear anywhere on the body).
• Nail lesions.

If this is the case, the way forward is to see a vet so they can thoroughly examine the affected areas and confirm whether it's fungi.

Diagnosis and Treatment for Fungi

Diagnosis will be based on the medical history we can give the vet, examining the lesions, and some additional tests. One test will be the Wood's lamp. This is a lamp with ultraviolet light that detects the presence of fungi because they become fluorescent. Although this test only detects some cases of Microsporum canis infections; overall, in small animals, it only detects 30-40% of cases.

To find out what type of fungus is affecting the dog, hair samples are also likely to be taken (a trichogram to see whether fungi are attached to them). Another measure is a culture with hair or skin samples, to confirm the presence of fungi and the appropriate treatment.

Treatment for fungi in dogs can vary depending on the type of condition and the severity of the lesions it has. Normally, the vet will prescribe antifungal medications, for example ketoconazole, enilconazole, or itraconazole. Many animals improve clinically but remain positive on fungal culture.

Tips for Caring for a Dog With Fungi

For the fungi to go away as soon as possible, along with the discomfort the dog experiences, it's important to keep in mind a series of recommendations that will help prevent the infection from spreading. The main ones are:

1. If there are other animals or children at home, don't let the dog sleep with them or share blankets or brushes. There's a high chance other animals could play a role in spreading the disease.
2. Wash your hands thoroughly with soap after being in contact with the dog; also disinfect, if you can, the areas of the house where your dog has been, and throw away any objects that could be contaminated.
3. If it rides in the car or gets on the sofa, cover these places beforehand with a blanket or a sheet and wash it afterward.

As you may have guessed from these last tips, fungi in dogs can be spread to humans through contact.

In most healthy people, fungal infections are mild, only affect the skin, hair, nails, or other superficial areas, and resolve on their own. However, in people with a weakened immune system, infections can persist for a long time and even become a significant health risk.

That's why it's important to follow the treatment a professional gives us and take every precaution you can so the fungi don't affect other family members and stop bothering our beloved adventure companion as soon as possible.