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About Fungal Infection in Dogs

Fungal infections can affect your dog's breathing, skin, or internal organs making your pooch uncomfortable, and very sick. In today's post our Flat Rock vets explain a little about some of the most common fungal infections in dogs, their symptoms and how they can be treated.

Types of Fungal Infections in Dogs

While our Flat Rock vets typically see fewer fungal infections in dogs than either bacterial or viral infections, fungal infections can be just as serious and treating fungal infections can be challenging.

Your pooch could contract a fungal infection as a result of 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 dog's body.

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

Systematic fungal infections

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


Cryptococcus is a fungus found mainly in areas where large numbers of pigeons or other birds gather. This fungus can be inhaled by your dog, resulting in a lung infection. Cryptococcosis tends to begin in the dog's respiratory tract, but can go on to affect your pet's central nervous system, eyes, and skin. Symptoms of cryptococcosis vary from one dog to another but can include symptoms as wide ranging as skin lesions, lethargy, coughing, nasal discharge, and eye problems, to seizures and other neurologic abnormalities. Oral antifungal medications are typically used to treat dogs suffering from cryptococcosis, however it often needs to be administered for a year or longer. This condition can be difficult to treat and many dog's are unable to recover from this condition.


Caused by the fungus Blastomyces dermatitidis, blastomycosis most commonly takes the form of a lung infection. This fungus thrives near beaver dams and other areas with moist acidic soil rich in decaying vegetation, where hunting dogs are at the highest risk of inhaling fungal spores. While the infection is 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 dog's body you may notice symptoms such as lameness, blood in urine, eye problems, skin lesions around the toenails, and fever. When diagnosed and treated early oral anti-fungal medications can be a curative treatment.


Aspergillus is a species of fungus found in soil all around the world and is responsible for two main types of fungal infections seen in dogs:

Nasal Aspergillosis
  • While typically limited to a dog’s nasal passages and sinuses, Nasal Aspergillosis can go on to spread to your pup's bony nasal structures and occasionally the orbit of the eye and skull. Dogs with long narrow heads such as greyhounds and collies seem to be more susceptible to this systematic fungal infection. Symptoms include lethargy, bloody nasal discharge or nosebleeds, nasal pain, sneezing, or pain around the nose area. Treatment for Nasal Aspergillosis typically involves infusing the affected dog's nasal passages with a liquid anti-fungal medication. Most dog's recover well following treatment although in some cases a second round of treatment is required.
Disseminated Aspergillosis
  • Disseminated Aspergillosis is a more deadly and generalized fungal infection which 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 the pup's body. Most often seen in German shepherds, this infection is slow to develop, with a range of symptoms that can include back pain, lameness, loss of appetite, muscle wasting, weakness, vomiting, blood in urine, urinary accidents, swollen lymph nodes and even paralysis. Unfortunately the prognosis for dogs with disseminated aspergillosis is poor, although in rare cases treatment can be successful. 

Localized (Skin) Fungal Infections in Dogs

It can be difficult for pet parents to recognize that their dog has a localized fungal infection because the itching and scratching that go hand-in-hand with these infections is often thought to be the result of dry skin or fleas. Localized fungal infections commonly seen by our vets include ringworm and fungal dermatitis.

Ringworm (Dermatophytes)

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

Treatment your dog's ringworm will depend upon the severity of your pup's infection but may include a combination of medicated baths and dips and/or oral antifungal medications. It will also be important to vacuum and disinfect your home frequently in order to help prevent the spread of ringworm to others in your household.

Fungal Dermatitis

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

Treatment of fungal dermatitis may be an ongoing effort. If your dog has a compromised immune system or allergy, fungal dermatitis may be difficult to treat. Some dogs will experience secondary yeast or bacterial skin infections along with severe skin allergies multiple times a year. If this is the case for your pup, your vet will work with you to develop a custom treatment plan to address your dog's health concerns.

Is your dog showing symptoms of a fungal infection? Contact our Flat Rock veterinary clinic to book an appointment with our veterinary dermatology team. 

Fungal infections in dogs, Flat Rock Vet

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