13 Symptoms of Fungal Skin Infections in Dogs

You might think nothing of your dog’s itchy paws or the small sore that’s formed on their leg, but these seemingly minor issues can be signs of a fungal infection. 

Fungi are parasitic organisms that produce spores and absorb food from hosts, such as your dog. Many types of fungi exist, but it’s most common for dogs to become infected by fungi that live in the soil. Your dog might inhale or ingest this fungi, or the fungi might get into their body through a cut or wound.

Fungal infections can be irritating and uncomfortable for dogs, but they can also affect their organs. When you’re familiar with the common signs of fungal infections in dogs, you can quickly recognize the problem and get your dog to the veterinarian for the treatment they need. 

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Signs of a fungal infection in dogs

Fungal infections can cause many symptoms in dogs. Here are 13 of the most common: 

1. Skin sores

2. Itchy skin

3. Skin lesions that drain

4. Hair loss 

5. Fever

6. Limp and swollen joints 

7. Nasal discharge

8. Blood in urine

9. Cough

10. Poor body condition

11. Loss of appetite

12. Weight loss

13. Blindness

The symptoms that your dog experiences will depend on the type of infection and whether the  infection is limited to their skin, or local, versus a systemic infection. 

According to Jamie Whittenburg, DVM, chief of staff at Kingsgate Animal Hospital in Lubbock, Texas, when fungal infections are limited to the skin, they most often affect certain areas. These include the external ear canals, area around the toenails, groin and armpits. But systemic infections can spread throughout a dog’s body, she told GoodRx Health, affecting major organs such as the lungs and liver. These infections can be life-threatening. 

Symptoms including skin sores, nasal discharge, and itchy skin may indicate a local infection. If the infection is systemic, you may see other, more widespread symptoms, such as blood in your dog's urine. 

Types of fungal infections in dogs

There are several common types of fungal infections in dogs. Each type of infection is caused by a different type of fungus, and the infections cause different symptoms. 

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Histoplasmosis

A fungus called Histoplasma causes histoplasmosis. This fungus is often found in soil that has a high nitrogen content, such as soil that’s been contaminated with bird or bat droppings. 

Your dog can inhale the fungal spores, and those spores become a yeast once they’re in your dog’s lungs. Histoplasmosis can be localized to your dog’s lungs, or it can travel through their blood and affect other organs. 

Blastomycosis

A fungus called Blastomyces lives in moist soil and decomposing wood and leaves. This fungus causes an infection called blastomycosis. Blastomyces is primarily found in:

• Great Lakes region

• Mississippi River valleys

• Ohio

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A blastomycosis infection occurs when a dog inhales the fungus spores and they transform into yeast in the lungs. The infection can stay within the lungs, or it can travel through the bloodstream and affect other organs. 

Coccidioidomycosis 

Coccidioidomycosis, also called Valley fever, is caused by the fungus Coccidioides, which is found in soil in warm, arid climates. This fungus is primarily found in: 

• Arizona

• California

• Nevada

• New Mexico

• Oregon

• Texas

• Utah

• Washington

If the soil is disturbed by an event such as a dust storm or construction, your dog may inhale the spores in the soil. Once in your dog's body, the spores transform into yeast and cause a fungal infection. 

Ringworm

Ringworm is caused by several different fungi, including: 

• Microsporum canis

• Microsporum gypseum

• Trichophyton mentagrophytes 

These fungi spread easily. And your dog can become infected through contact with objects, such as furniture or grooming tools, that contain the spores. 

Ringworm infections most often affect the face, ear tips, tail, and feet. It’s common for infected dogs to develop scaly patches and experience hair breakage or loss. 

Fungal dermatitis (yeast infection) 

Malassezia dermatitis is a common fungal yeast infection in dogs. Malassezia are organisms that live naturally on the surface of the skin. Fungal dermatitis occurs when there’s an overgrowth of these organisms. 

Several conditions on a dog’s skin can cause the organisms to overgrow, such as:

• Increase in skin oils during an allergy flare-up

• Immune deficiency

• Excess oil production (seborrhea)

Is my dog’s fungal infection contagious?

Whittenburg said some fungal infections in dogs are contagious to other pets and humans, but others are not. 

“Malassezia spp. are fungal organisms that are normally present on the skin but can overgrow and cause a skin infection. These infections are not contagious,” she said. “On the other hand, ringworm (most often Microsporum canis) is contagious between dogs, cats, humans, and other animals.”

If you suspect your dog has a fungal infection, it’s best to assume the infection is contagious until your veterinarian diagnoses the specific type.

To prevent the spread of a fungal infection: 

• Keep your dog away from other pets in your home. 

• Limit how much you and other people are in contact with your dog.

• Wear long sleeves and gloves when you do handle your dog. 

• Schedule an appointment with your veterinarian right away, so you can confirm whether your dog’s fungal infection is contagious. 

Treatment options for fungal infections in dogs

Before treating your dog, your veterinarian will diagnose the specific type of fungus causing the infection. Then, your vet will tailor a fungal infection treatment to your dog and their condition, Whittenburg said. This could include medicated shampoo or topical ointment. 

Your vet may also prescribe an oral antifungal medication, such as:

• Itraconazole (Itrafungol)

• Fluconazole (Diflucan)

• Terbinafine (Lamisil)

• Griseofulvin (Fulvicin)

In addition, your veterinarian will want to address any underlying condition that is causing the fungal skin infection, such as allergies, Whittenburg said.

What happens if a fungal infection is left untreated in dogs?

“Left untreated, fungal skin infections in dogs can lead to severe itching and discomfort, self-mutilation injuries, secondary bacterial infections, and other complications,” Whittenburg said. 

In addition, she said, “In the case of ringworm, the untreated pet will contaminate the environment and spread the condition to others.” 

Systemic fungal infections can progress to serious and even life-threatening symptoms. For example, blastomycosis can cause difficulty urinating, bloody nasal discharge, and ultimately an infection in your dog’s brain. 

Getting your dog prompt treatment can keep them more comfortable. And hopefully your veterinarian can start treating the fungal infection before it has progressed and caused these more severe symptoms. 

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Written by:

Paige Cerulli

Paige Cerulli is a freelance writer who specializes in pet and animal topics. She studied English and music performance at Westfield State University.

Edited by:

Renée Fabian, MA

Renée Fabian is the senior pet health editor at GoodRx. She’s worked for nearly 10 years as a journalist and editor across a wide range of health and well-being topics.

Reviewed by:

Ghanasyam Bey, DVM

Ghanasyam Bey, DVM, is from Cleveland, Ohio, and attended Princeton University for undergraduate studies. After a year of biology research at Duke University, he attended Ohio State College of Veterinary Medicine.

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