When it comes to your dog's health, skin issues can be a real concern — especially when you are unsure what is causing the problem. Fungal skin infections are a common but often overlooked issue that can make your dog uncomfortable, leading to itching, rashes, and hot spots that may need prompt treatment.
Understanding the different types of fungal skin infections, recognizing the signs, and knowing your treatment options can help you address the problem early and keep your dog healthy.
Types of Dog Skin Fungal Infections
Several types of fungal infections can affect your dog's skin. Knowing what to look for and understanding the risk factors can help you identify and address these infections early.
Fungal dermatitis (yeast dermatitis)
Fungal dermatitis is the most common fungal skin infection in dogs. It is caused by an overgrowth of Malassezia, a type of yeast that normally lives on your dog's skin in small amounts. When something disrupts the balance of the skin's natural microbiome — such as food or environmental allergies — this yeast can overgrow and take over.
Overgrowth of Malassezia leads to irritation, redness, itching, and a musty, unpleasant smell. Dogs with floppy ears or skin folds are especially prone to this condition. For more on how allergies contribute to skin problems, see our guide on allergies in dogs.
Blastomycosis
Blastomycosis is a more serious fungal infection caused by inhaling spores of the Blastomyces dermatitidis fungus, which is found in soil and decaying organic matter. Once inhaled, the spores can travel from the lungs to the skin, where they cause lesions, ulcers, and nodules.
Aspergillosis
Aspergillosis is caused by the Aspergillus fungus, commonly found in soil, hay, and dust. Dogs typically contract this infection by inhaling spores, which can lead to localized infections in the nasal passages or, in more severe cases, systemic infections. If the infection spreads to the skin, it can cause lesions and ulcers.
Cryptococcosis
Cryptococcosis is caused by Cryptococcus neoformans, a fungus found in soil and pigeon droppings. Dogs typically contract this infection by inhaling spores, which can lead to respiratory symptoms and, in severe cases, skin lesions. Dogs with weakened immune systems are at higher risk.
Candidiasis
Candidiasis is caused by Candida species, particularly Candida albicans, a yeast that normally lives in the gastrointestinal tract and on mucous membranes. When the balance of normal flora is disrupted, Candida can overgrow and lead to skin infections. This condition often appears as red, itchy, and moist skin lesions.
Histoplasmosis
Histoplasmosis is caused by inhaling spores of the Histoplasma capsulatum fungus, often found in soil contaminated with bird or bat droppings. While it primarily affects the lungs, it can spread to the skin, causing ulcers and nodules.
What Causes Dog Fungal Skin Infections?
Fungal skin infections in dogs are caused by various types of fungi that invade the skin, usually when the skin's natural barriers are compromised. A healthy immune system generally keeps these fungi in check, but certain factors can increase your dog's risk.
Environmental conditions play a significant role. Warm, humid climates create ideal conditions for fungi to thrive. Dogs that spend a lot of time outdoors, especially in moist soil or areas with decaying organic matter, are at higher risk of exposure.
Dogs with underlying health conditions such as allergies, diabetes, or a weakened immune system are more susceptible to fungal infections. Certain medications, including corticosteroids and other allergy medications, can suppress the immune system and further increase risk.
Poor grooming habits can also contribute. Matted fur traps moisture against the skin, creating the perfect environment for fungal overgrowth. Regular grooming appropriate for your dog's coat type and lifestyle helps maintain a healthy skin barrier and prevents the buildup of dirt and moisture where fungi can grow.
Signs and Symptoms of Dog Skin Fungal Infections
Recognizing the signs of a fungal skin infection early is important for effective treatment. Symptoms can vary depending on the type of fungus and the severity of the infection, but several common signs are worth watching for.
Persistent itching and scratching are among the most noticeable symptoms. You may also see red, inflamed skin that looks sore and irritated. In cases of fungal dermatitis, the skin may develop a greasy or scaly texture and produce an unpleasant musty odor. Other symptoms include hair loss, crusty or thickened skin, and the presence of ulcers or nodules.
Systemic fungal infections such as blastomycosis or histoplasmosis can cause more severe symptoms including lethargy, weight loss, fever, and respiratory issues. If the infection spreads to the skin, you may notice slow-healing lesions or ulcers. If you observe any of these signs, have your dog examined by a veterinarian as soon as possible.
How Are Dog Skin Fungal Infections Diagnosed?
Diagnosing a fungal skin infection typically involves a physical exam, diagnostic testing, and a review of your dog's medical history. Your veterinarian will start by examining the affected skin areas, looking for visible signs like redness, hair loss, or lesions. They will ask about your dog's environment, grooming habits, and any underlying health conditions.
To confirm the diagnosis, your veterinarian may collect a sample using a skin scraping or impression smear (pressing a glass slide onto the skin to collect cells). This sample is examined under a microscope to determine whether fungal overgrowth is present. In some cases, a biopsy — collecting a larger piece of tissue — may be sent to a lab for further analysis.
These tests help identify the specific type of fungus involved, which is crucial for determining the most effective treatment plan. For systemic infections, blood tests, urine tests, or imaging studies may also be needed to assess whether the infection has spread to other parts of the body.
How Are Dog Skin Fungal Infections Treated?
Treatment depends on the type and severity of the infection.
Mild cases of fungal dermatitis can often be managed with topical antifungal products applied directly to the affected areas. DermaBliss Anti-Bacterial & Anti-Fungal Spray provides targeted relief for localized fungal skin irritation. DermaBliss Anti-Bacterial & Anti-Fungal Wipes offer a convenient option for cleaning affected areas between baths. For more widespread fungal dermatitis, DermaBliss Anti-Bacterial & Anti-Fungal Shampoo can help treat the infection across larger skin areas during regular bathing.
For dogs dealing with the allergies that often trigger fungal overgrowth, DermaBliss Advanced Seasonal Allergy Health Chews can help manage the underlying immune response. Explore the full range of skin care products in the DermaBliss collection.
For more severe infections, your veterinarian may prescribe oral antifungal medications to clear the infection from within. Systemic fungal infections like blastomycosis or histoplasmosis require more intensive treatment — often long-term oral antifungal therapy lasting several months to ensure the infection is fully eliminated. Additional supportive care such as pain management, anti-inflammatory medications, or intravenous fluids may be necessary to manage symptoms and complications.
During treatment, it is important to follow your veterinarian's instructions carefully and complete the full course of medication, even if your dog's symptoms seem to improve. Stopping treatment too early can lead to recurrence, which may be harder to treat the second time around.
Tips for Preventing Dog Skin Fungal Infections
Preventing fungal skin infections involves good hygiene, regular grooming, and environmental management. Keeping your dog clean and dry is one of the most important steps for preventing fungal growth.
Identifying and managing any underlying allergies — whether food or environmental — is also essential, as allergies are one of the most common predisposing factors for fungal skin infections, particularly Malassezia overgrowth. For more on identifying and managing allergies, see our comprehensive guide on allergies in dogs.
Check your dog's skin and coat regularly for signs of irritation, and keep their living environment clean and dry. If your dog spends a lot of time outdoors, especially in areas with moist soil, wash and dry them thoroughly afterward. In regions where certain fungal infections like blastomycosis or histoplasmosis are more common, consider limiting your dog's exposure to high-risk environments.
Regular veterinary checkups and prompt attention to any skin changes will go a long way in catching fungal issues early — before they become serious.
For more on how ear infections relate to skin health, or for a broader overview of skin conditions and allergy management, visit our resource on allergies in dogs.
