Nasal Aspergillosis in Dogs
Nasal aspergillosis is an infection of the inside of the nose and sinuses caused by a microscopic fungus, Aspergillus, which is widespread in the environment. The fungus settles in the nose, gradually destroys the delicate bone structures f...
What is it?
Nasal aspergillosis is an infection of the inside of the nose and sinuses caused by a microscopic fungus, Aspergillus, which is widespread in the environment.
The fungus settles in the nose, gradually destroys the delicate bone structures found there, and causes significant inflammation.
It mainly affects dogs with long or medium-length muzzles.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
Nasal discharge lasting weeks, thick, sometimes purulent and tinged with blood, often from one side initially and sometimes from both.
Nosebleeds, sometimes repeated.
Nose losing its color (becoming pink or gray), or developing crusts and small sores around the nostrils.
Muzzle pain: the dog avoids having his head or face touched, or becomes irritable when approached.
Sneezing and reverse sneezing.
The dog sometimes rubs his nose.
Decreased appetite or lethargy in some dogs, often linked to pain.
Rarely, when the infection reaches the base of the skull, nervous signs may appear: disorientation, seizures.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
The infection is caused by a fungus of the Aspergillus genus, most commonly Aspergillus fumigatus.
This fungus lives everywhere in the environment: soil, decomposing vegetation, hay, straw, compost, dust. Its spores are present in the air that all dogs breathe.
It is not completely understood why some dogs develop the infection while most resist it. A prior injury to the nose, such as a foreign body or tumor, is sometimes found.
Dogs with long or medium muzzles are at higher risk; flat-faced breeds are rarely affected.
The disease often occurs in young adult or middle-aged dogs.
A pre-existing injury inside the nose—such as a foreign body, trauma, or tumor—is sometimes found.
Transmission
The dog becomes infected from the environment by breathing in fungal spores, not through contact with another dog.
An infected dog does not transmit the infection to other animals in the household under normal living conditions.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian examines the nose, nose pad, face, mouth, and teeth, palpates the muzzle to check for pain, and verifies airflow through each nostril.
Diagnosis requires examinations under anesthesia: a head scan shows the characteristic destruction inside the nose and any involvement of the sinuses and base of the skull.
Rhinoscopy—examination of the inside of the nose with a small camera—allows the veterinarian to see fungal patches and take samples for analysis.
Blood tests may complete the workup.
In Tunisia, nosebleeds also prompt screening for leishmaniasis and tick-borne diseases, which can cause bleeding.
Treatment
Treatment relies on an antifungal medication prescribed by the veterinarian.
The most common treatment involves cleaning the inside of the nose under anesthesia by removing fungal patches, then applying the antifungal directly into the nasal cavities. Several sessions may be needed.
Antifungal medication by mouth may be offered depending on the case, as a complement or when local treatment is not possible.
Pain relief medication helps ease the dog's discomfort.
These procedures often require a veterinarian equipped for endoscopy.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
There is no vaccine or guaranteed prevention, since the fungus is present everywhere.
Limit your dog's exposure to sources heavily laden with spores: moldy hay or straw, compost, and decomposing vegetation piles.
Have your dog examined promptly if its nose runs for several weeks or if the nose pad changes in appearance.
Possible complications
Lasting destruction of the internal structures of the nose, with discharge that may persist after healing.
Spread to the sinuses and, rarely, to the base of the skull, with neurological symptoms.
Repeated nosebleeds.
Relapse after initial treatment, requiring additional sessions.
When to see a veterinarian
Your dog is disoriented or having seizures: seek emergency care.
It is bleeding heavily from the nose, or bleeding repeatedly: consult the same day.
Its nose pad is discolored, or covered with crusts or sores around the nostrils, while its nose is running.
Its nose has been running for several weeks, especially from one side only.
It is painful when you touch its muzzle, or avoids having its head touched.
Its signs return after treatment.
Prognosis
With appropriate treatment, many dogs recover or show significant improvement, though several treatment sessions may sometimes be needed.
A mild nasal discharge may persist after recovery, as the inside of the nose remains damaged.
The outlook is more guarded when the infection has reached the base of the skull.
Frequently asked questions
How to distinguish it from a nasal tumor?
Both produce persistent nasal discharge and nosebleeds. Aspergillosis typically affects a young adult or middle-aged dog, causes a painful muzzle, and often damages the nose pad. Tumors typically occur in older dogs, deform the muzzle or cause one eye to protrude, with a normal nose pad. Only CT scanning and sampling can definitively distinguish between them.
My dog is bleeding from the nose and losing weight: could it be aspergillosis?
Not necessarily. In Tunisia, leishmaniasis and tick-borne diseases, such as ehrlichiosis, can also cause nosebleeds, often accompanied by weight loss, fever, skin lesions, or swollen lymph nodes. The veterinarian searches for these through a blood test.
Can I catch a disease from my dog?
No, not directly. The fungus comes from the environment, not from the dog. If your immune defenses are weakened, avoid handling moldy hay or vegetation and talk to your doctor about it.
Why is the treatment performed under anesthesia?
Because the fungus forms plaques at the back of the nose that need to be removed, and the antifungal must be applied directly to them. These procedures require the dog to be sedated.
References
Content reviewed by the TunisieVet editorial team · Updated 10 October 2026
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