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Symptoms of Fungal Infection in Dogs

Fungal infections can affect your dog's breathing, skin, or internal organs making your canine companion uncomfortable, and very sick. Here our Orange County vets explain the symptoms of some of the most common fungal infections in dogs, and how they can be treated.

Fungal Infections in Dogs

Although our Orange County vets typically see more viral and bacterial infections in dogs, fungal infections can be just as serious and treating them can be challenging.

Fungal infections can result from contact with an infected animal, encountering the fungus in the environment, or due to an overgrowth of the fungi (yeast) which is naturally present in and on your pet's body.

There are two main types of fungal infections commonly seen in dogs, systematic fungal infections which affect your dog's major body systems, and localized fungal infections that are seen on your dog's external features or skin.

Systematic fungal infections

Systematic fungal infections invade the inner workings of your pup's body, often attacking your pet's nasal passages, lungs, bones or eyes. Aspergillosis, Cryptococcosis, and Blastomycosis are three of the most common systematic fungal infections seen in dogs throughout the US. 


Cryptococcus is a fungus that thrives in areas where large numbers of pigeons or other birds gather. Because the fungus is inhaled by your dog, Cryptococcosis infections typically begin in the dog's respiratory tract, but can go on to affect your pet's central nervous system, eyes, and skin. The symptoms of cryptococcosis vary widely but can include skin lesions, lethargy, coughing, nasal discharge, eye problems, seizures and other neurologic abnormalities. Cryptococcus in dogs is most often treated with oral antifungal medications but this condition can be difficult to beat. Many dog's require medication for a year or more, and some are unable to recover.


The Blastomyces dermatitidis fungus which causes this condition thrives near beaver dams and other areas with moist acidic soil rich in decaying vegetation. Because of where this fungus is found hunting dogs are at the highest risk of inhaling these spores. While the infection is still contained within the lungs symptoms of blastomycosis include coughing, fever, lethargy, loss of appetite, and weight loss, however, if the infection reaches other areas of your pup's body you may notice symptoms such as lameness, blood in urine, eye problems, skin lesions around the toenails, and fever. If your dog is displaying any of the symptoms of Blastomycosis book an appointment with your vet as soon as possible. If caught in the early stages oral anti-fungal medications can be a curative.


Found in soil across the globe Aspergillus is a species of fungus that is responsible for two types of fungal infections seen in dogs:

Nasal Aspergillosis
  • Although this fungal infection is typically limited to a dog’s nasal passages and sinuses, it can go on to spread to your dog's bony nasal structures and occasionally the orbit of the dog's eye and skull. Breeds with long narrow heads such as greyhounds and collies seem to be more susceptible to this systematic fungal infection. Symptoms of Nasal Aspergillosis include lethargy, bloody nasal discharge or nosebleeds, nasal pain, sneezing, or pain around the nose area. Treatment for this condition usually includes infusing the affected pup's nasal passages with a liquid antifungal medication. With treatment most dogs recover well, although in some cases a second round of treatment is required.
Disseminated Aspergillosis
  • Disseminated Aspergillosis is a much more serious fungal infection that can affect your dog's bones, muscles or organs. The fungus enters your dog's respiratory tract then makes its way into the bloodstream and throughout your dog's body. Most often seen in German shepherds, this infection is slow to develop, and can result in symptoms as diverse as back pain, lameness, loss of appetite, muscle wasting, weakness, vomiting, blood in urine, urinary accidents, swollen lymph nodes and even paralysis. Sadly, the prognosis is poor for dogs with disseminated aspergillosis, although in some rare cases treatment can be successful. 

Localized Fungal Infections in Dogs

Spotting a localized fungal infection can be tricky since the itching and scratching that go hand-in-hand with these infections is often thought to be the result of dry skin or fleas. Some of the most common localized fungal infections seen by our vets include ringworm and fungal dermatitis.

Ringworm (Dermatophytes)

Ringworm is caused by a collection of pathogenic fungi. Ringworm is extremely contagious and spread when your dog comes in direct contact with an infected animal, person, or object such as a carpet, couch, comb, bowl, or bedding. Symptoms of this condition affect your dog’s skin, fur, or nails and typically include hair loss, itching, flaky or crusty skin, and brittle or misshapen nails. Early diagnosis and treatment are essential in preventing the spread of ringworm to other pets and people within your household! 

Ringworm treatment for dogs will depend upon the severity of your pet's infection but may include a combination of medicated baths and dips and/or oral antifungal medications. You will also need to vacuum and disinfect your home frequently in order to help prevent the infection from spreading to others.

Fungal Dermatitis

Fungal dermatitis, is a common inflammatory skin condition that can occur when the yeast which normally lives in your pet’s ears, mucocutaneous areas and skin, reproduces uncontrollably and overpopulates these areas. The symptoms of fungal dermatitis in dogs include intense itchiness, flaky or crusty skin (particularly around your dog's nails, skin folds, armpits and anal area), and ear infections. Treatment for this condition may include antibiotics combined with topical anti-fungal treatments such as shampoos, or ear solutions.

Fungal dermatitis can be tricky to beat, particularly if your dog suffers from a compromised immune system or allergies. Some dogs will experience recurring secondary yeast or bacterial skin infections along with severe skin allergies. If this is the case for your pet, your veterinarian will work with you to develop a custom treatment plan to address your dog's health concerns.

Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.

Is your dog suffering from a stubborn fungal infection? Speak to your vet about a referral for your dog to be seen by our Board Certified Internal Medicine Specialist. Our veterinary specialists work with your primary care vet to provide your dog with the best possible care. Contact us to find out more.

New Patients Welcome

Veterinary Medical And Surgical Group–OC (VMSG-OC) accepts new clients to our specialty services and 24/7 emergency services.

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