Aspergillosis in Dogs

See your vet immediately if your dog has repeated nosebleeds, thick nasal discharge, facial pain, eye swelling, trouble breathing, or seems generally very ill. Aspergillosis is a fungal infection caused by Aspergillus species, molds that are common in the environment. Dogs usually become infected after inhaling fungal spores. In many cases the infection stays in the nose and sinuses, which is called nasal aspergillosis. Less often, the fungus spreads beyond the respiratory tract into organs, bones, eyes, or the nervous system. That form is called disseminated aspergillosis.

Nasal aspergillosis is the form most pet parents hear about. It tends to cause chronic nasal signs that do not improve with routine antibiotics alone. Dogs may have discharge from one or both nostrils, sneezing, pain around the muzzle, and irritation or ulceration at the nostrils. Some dogs also develop facial swelling or changes around the eyes if nearby tissues are affected. Long-nosed breeds appear overrepresented, although any dog can be affected.

Disseminated aspergillosis is less common but much more serious. It can affect multiple body systems and may look very different from dog to dog. Signs may include fever, poor appetite, weight loss, weakness, spinal pain, lameness, enlarged lymph nodes, eye inflammation, or neurologic changes. Because the signs can be vague at first, diagnosis is sometimes delayed.

This is not a condition pet parents can confirm at home. Aspergillosis can mimic chronic rhinitis, foreign material in the nose, dental disease, nasal tumors, and other fungal infections. Your vet may recommend anything from a focused nasal workup to referral for advanced imaging and specialty treatment, depending on how sick your dog is and whether the infection appears localized or widespread.

Diagnosing aspergillosis usually takes more than one test. Your vet will start with a physical exam and history, including how long the nasal signs have been present, whether the discharge is one-sided or two-sided, and whether your dog has had weight loss, lameness, or neurologic changes. Basic bloodwork and urinalysis help look for inflammation, organ involvement, and whether antifungal treatment would be safe if needed.

For dogs with nasal signs, imaging is often an important next step. Skull radiographs may show changes, but CT is usually more informative because it can reveal destruction of the nasal turbinates, sinus involvement, and whether there is concern for a tumor or foreign material. Rhinoscopy lets your vet or a specialist look directly into the nasal passages, collect samples, and sometimes see fungal plaques.

Testing may include biopsy, cytology, fungal culture, PCR, and antibody or antigen testing. One challenge is that Aspergillus can be present in the environment, so a culture by itself does not always prove disease. Merck notes that nasal culture and serology can produce misleading results, which is why diagnosis is usually based on the full picture: signs, imaging, direct visualization, and tissue or sample findings.

If disseminated aspergillosis is suspected, the workup may expand to chest imaging, abdominal ultrasound, spinal imaging, urine testing, lymph node or organ aspirates, and fungal testing on tissue, blood, or urine. Referral is common in these cases because the disease can affect several organs at once and may need advanced sampling or imaging to confirm.

Aspergillosis is caused by inhaling spores from Aspergillus molds in the environment. These fungi are common in soil, decaying vegetation, compost, and other organic material. Exposure alone does not mean a dog will become sick. Most dogs inhale fungal spores at some point without developing disease, which suggests that local nasal defenses, immune response, and individual susceptibility all matter.

Nasal aspergillosis is seen more often in dolichocephalic, or long-nosed, breeds such as Collies, Greyhounds, and Dachshunds. VCA also notes increased incidence in some retrievers and Rottweilers in certain reports. The reason is not fully understood, but nasal anatomy may play a role in how spores are trapped and how infection becomes established.

Disseminated aspergillosis appears to have different risk patterns. German Shepherd Dogs are classically overrepresented, and some reports note a higher frequency in females. Dogs with immune dysfunction, chronic illness, or unusual exposure may also be at higher risk, although disseminated disease can still occur without an obvious trigger.

This infection is not usually considered contagious from dog to dog in the way kennel cough is. The concern is environmental exposure and the dog’s own susceptibility, not routine contact with another pet. Even so, if one dog in the household is diagnosed, it is reasonable to tell your vet about any similar signs in other pets so they can decide whether evaluation is needed.

There is no vaccine that prevents aspergillosis in dogs, and complete avoidance is not realistic because Aspergillus molds are widespread in the environment. Even healthy dogs are exposed to fungal spores while sniffing outdoors. Prevention is therefore more about reducing heavy exposure and acting early when signs appear.

If your dog loves digging, rooting through compost, or spending time around moldy hay, decaying plant material, or damp organic debris, it makes sense to limit those activities when possible. This is especially reasonable for dogs with chronic nasal disease, dogs with known immune problems, or breeds that may be predisposed to nasal fungal infection.

Prompt evaluation matters. Chronic nasal discharge, repeated sneezing, or intermittent nosebleeds are often mistaken for allergies or a minor upper respiratory issue. Early workup may help your vet identify fungal disease before there is more tissue destruction or spread to nearby structures.

For dogs being treated for aspergillosis, prevention also means follow-up. Recheck visits, repeat imaging or rhinoscopy when recommended, and blood monitoring during systemic antifungal therapy can help catch relapse, medication side effects, or progression before the situation becomes more difficult to manage.

The outlook depends heavily on which form of aspergillosis your dog has. Dogs with localized nasal aspergillosis often have a fair to good outlook when the disease is diagnosed early and treated with targeted local therapy. Recovery can still take time, and some dogs need repeat treatment because fungal plaques can be stubborn or because the infection has already damaged nasal tissues.

During recovery, pet parents may still notice some sneezing, mild discharge, or temporary irritation after procedures. Your vet may recommend rechecks to confirm that the infection is clearing rather than assuming improvement at home means the fungus is gone. If oral antifungal medication is used, blood monitoring is important because some drugs can affect the liver.

The prognosis is more guarded for sino-orbital disease and much more serious for disseminated aspergillosis. Merck describes disseminated disease as guarded to grave because many dogs already have advanced, rapidly progressive illness by the time they are diagnosed. Some dogs can achieve remission or meaningful control with long-term antifungal treatment, but outcomes vary widely depending on which organs are involved and how well the dog tolerates therapy.

It is reasonable to ask your vet what success looks like for your individual dog. In one case that may mean clearing a nasal infection with one or two procedures. In another, it may mean managing a chronic systemic infection for months while tracking comfort, mobility, appetite, and organ function. A realistic plan is often the most helpful one.