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). Infections caused by fungi are relatively common in dogs and are more likely to develop when a dog’s immune system is weakened or when the skin barrier is compromised. This can happen due to underlying health issues, such as allergies, wounds, hormonal imbalances and more. Here are some of the common and not-so-common fungal infections that can affect dogs and, in some cases, be passed to people, too.
Yeast Infection in Dogs (Malassezia Dermatitis)
Malassezia pachydermatis is a type of yeast that is normally present on your dog’s skin and ears in small numbers. However, under certain conditions, like allergies, hypothyroidism, oily skin or a weakened immune system, it can overgrow and lead to infection. Dogs with Malassezia dermatitis often develop greasy, smelly skin, intense itching, thickened areas of darkened skin and recurrent ear infections. You might notice your dog scratching, licking or chewing certain areas more than usual.
What Causes Yeast Infections in Dogs?
While Malassezia pachydermitis is normally harmless, certain factors can disrupt the skin’s balance and allow it to multiply excessively. Underlying health conditions often play a major role and result in secondary yeast infections. Additionally, high humidity and temperatures can increase the risk of opportunistic yeast infections. But there is some good news — M. pachydermatis is not contagious, so it won’t spread to other pets or humans.
Yeast can spread all over a dog’s body, but it prefers moist, warm places like in a dog’s ears, between their toes, in skin folds, and around their neck, armpits and groin. If your dog has yeast dermatitis or a yeast ear infection, they will probably be scratching, chewing and rubbing frenziedly in an effort to relieve the itching. Other symptoms include redness, smelly, crusty and thickened skin and darkly pigmented skin. Chronic ear infections in dogs are commonly linked to yeast overgrowth in the ear canal and can become a recurring problem if not properly addressed.
Treating a Yeast Infection in Dogs
If your veterinarian suspects your dog has yeast dermatitis, they will typically examine a sample of your dog’s skin debris under a microscope after staining it with a specific dye that highlights the presence of yeast. Once a diagnosis is confirmed, appropriate treatment will be recommended. Antifungal medication is available in both topical and oral treatment forms for treating yeast dermatitis and ear yeast infections. Medicated shampoos and ointments (for small areas) are used for mild yeast dermatitis, but more severe yeast infections may require a combination of topical and oral antifungal medications. Your veterinarian will also work to identify and address any underlying health issues that may have triggered the yeast overgrowth in the first place. Managing underlying causes is essential for clearing an infection and also for preventing future flare-ups.
Ringworm in Dogs
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, hair loss and easily broken nails. Dogs with weakened immune systems, existing skin problems (e.g., from allergies or fleas), and dogs that have open wounds, 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 others who live in the same house as an animal (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 human.
Treating Ringworm in Dogs
For an accurate diagnosis of ringworm, skin and hair samples are collected from your dog. Your veterinarian can examine your dog’s hair under a microscope, or they can perform a fungal culture to confirm the presence of ringworm. Treatment typically includes a medicated shampoo with or without oral antifungal medications.
Hygiene is important with a ringworm infection. To reduce the spread (and recurrence) of ringworm, limit household contact with affected dogs while they are undergoing treatment (and shedding infectious spores), and clean and disinfect your house often.
Other Types of Fungal Skin Infections in Dogs
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. While it usually starts as a skin infection, sporotrichosis can spread to other parts of the body and can be transmitted to other animals and people. Recovery is slow, as 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 fresh water. Surgery and long-term antifungal medications are often used to try to control this infection, but treatment isn’t always successful.
Nasal aspergillosis is another rare fungal infection in dogs that affects the nasal passages. These fungi occur naturally in decaying leaves, compost piles and standing water. Dogs with a compromised immune system are more likely to be affected by aspergillosis. The most common clinical signs are a strong odor and thick discharge coming from the dog’s nose, sneezing and pawing at the nose (due to pain). Treatment with antifungal medication is often required for months or years.
A Fungal Skin Infection Is No Fun for Your Dog
If your dog is licking, chewing or scratching excessively, or if you notice changes in your dog’s skin and coat, contact your vet. Skin problems often have multiple contributing factors, and if a fungus is involved, it’s important to know which fungus so your veterinarian can determine the best treatment plan for your dog and you can keep the rest of your household healthy.
