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Fungal Skin Infections Are Anything but Fun for Your Dog

If you notice your dog scratching, biting, chewing or rubbing sooooo much that it causes bald spots or damages their skin, they may be at risk of developing a fungal skin infection (or already have one). Skin infections caused by fungi are relatively common in dogs and often develop as a result of an underlying health issue. Here are some of the common and not-so-common fungal skin infections that can affect dogs and, in some cases, be passed to people, too.

Malassezia Dermatitis (Yeast Infection)

Malassezia pachydermatis is a naturally occurring yeast normally found in small numbers on the skin and in the ears of dogs. However, underlying health conditions can promote the overgrowth of this opportunistic yeast, leading to an infection. High humidity and temperatures can also increase the risk of a yeast infection.

M. pachydermatis is a common cause of skin infections in dogs, particularly those with a weakened immune system, or dogs with allergies, hypothyroidism, a bacterial skin infection or other disease that affects the skin’s oil glands. But there is some good news — M. pachydermatis is not contagious.

If your dog has a yeast infection on their skin, they will probably be scratching, chewing and rubbing frenziedly to stop the itching. Their skin can be smelly and crusty and may become thickened and darkly pigmented. Yeast can spread all over your dog’s body, but it prefers moist, warm places like in their ears, between their toes, and in their neck, armpits or groin.

If your veterinarian suspects your dog has a yeast infection, they will typically use a microscope to look at skin debris that has been stained with a specific dye for diagnosing a yeast infection. Antifungals are available in both topical and oral forms for your veterinarian to treat yeast infections. Medicated shampoos and ointments (for small areas) are used for mild yeast infections, but more severe infections may require a combination of topical and oral antifungal medications. Your veterinarian will also treat any underlying health issues that may have caused the yeast infection to begin with.


Despite the name, a worm doesn’t actually cause ringworm — although it does look like a circular rash on the skin. It’s a common fungal infection in dogs that causes itchy and crusty skin, bald patches and easily broken nails. Dogs who have skin problems already (e.g., from allergies or fleas), or who have an open wound, have an increased risk of contracting ringworm.

Probably the most important fact to know about ringworm is that it is highly contagious and can spread between pets and people — especially those who live in the same house as a pet (or person) with ringworm. The spores from the ringworm fungus are released into the environment, so ringworm can be contracted from objects in the house, not just from direct contact with the infected pet or person.

Ringworm is diagnosed by examining your dog’s hair under a microscope or by doing a fungal culture of their skin cells or hair. Treatment typically includes a medicated shampoo with or without oral antifungal medications. An important step for reducing the spread (and recurrence) of ringworm is to limit household contact with your dog while they are undergoing treatment (and shedding infectious spores), and to clean and disinfect your house often.

Other Fungal Skin Infections

Two other fungal skin infections that can affect dogs (but are rare) include sporotrichosis and lagenidiosis. Sporotrichosis is caused by a fungus found naturally in soil and on plants. Skin infections usually occur via a wound caused by a foreign body (e.g., thorn or splinter) contaminated with the fungus. The sporotrichosis fungus can also affect other parts of the body and pass between animals and people. Treatment usually requires long-term use of antifungal medications.

Lagenidiosis affects the skin and the area underneath the skin but can also affect other parts of the body. It is caused by a mold typically found in warm and stagnant freshwater. Surgery and long-term antifungal medications are often used to try to control this infection, but treatment isn’t always successful.


If your dog is licking, chewing or scratching excessively, or if you notice changes in your dog’s skin and coat, contact your veterinarian. If it is a fungal skin infection, it’s important to know which fungus caused the infection so your veterinarian can provide the right treatment plan for your dog, and you can keep the rest of your household healthy.


RELATED POST: Getting a Grip on Your Dog’s Pododermatitis

The information in this blog has been developed with our veterinarian and is designed to help educate pet parents. If you have questions or concerns about your pet's health or nutrition, please talk with your veterinarian.


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