Nasal Aspergillosis in Dogs: Chronic Nasal Discharge and Care

A runny nose that comes and goes for a day or two is common in dogs, but a discharge that keeps returning for weeks deserves a closer look. Nasal aspergillosis is a fungal infection of the nasal passages and sinuses that tends to cause long-lasting, thick discharge, sometimes streaked with blood, along with a sore nose and changes in the color of the nostril. It is caused by a common environmental mold, and it most often affects long-nosed and medium-nosed dogs. This guide explains how the infection develops, the signs that warrant a veterinary exam, how veterinarians reach a diagnosis, what antifungal therapy involves, and how to care for your dog at home during recovery.

Important: This article shares general educational information for pet owners and is not a substitute for an in-person veterinary examination, diagnosis, or treatment. For any medical concern or emergency, contact your veterinarian promptly.

What Is Nasal Aspergillosis?

Aspergillosis is an infection caused by Aspergillus, a group of molds found widely in the environment. Dogs breathe in tiny fungal spores every day, and in most cases the normal defenses of the nose clear them without any trouble.

In nasal aspergillosis, the fungus takes hold on the lining of the nasal cavity and, often, the frontal sinuses above the eyes. It grows as mats of fungal material, sometimes called fungal plaques, that sit on the surface of the nasal lining. The infection triggers strong inflammation and gradually destroys the turbinates, the delicate scrolls of thin bone and tissue inside the nose that warm, humidify and filter the air a dog breathes.

Nasal aspergillosis usually stays within the nose and sinuses, which is why it is often called a sinonasal infection.

Which Dogs Are Most Often Affected?

Nasal aspergillosis can develop in any dog, but certain patterns are well recognized by veterinarians.

• Nose shape: long-nosed (dolichocephalic) and medium-nosed (mesocephalic) dogs are affected far more often than flat-faced breeds.
• Age: it is most commonly seen in young to middle-aged adult dogs, although older dogs can also be affected.
• Overall health: many affected dogs are otherwise healthy, though local immune responses in the nose are thought to play a role.
• Previous nasal damage: earlier injury to the nose, a lodged foreign object such as a grass seed, or a past nasal procedure may make it easier for the fungus to become established.

Signs That Warrant a Veterinary Exam

Signs usually build slowly, and many dogs stay bright and energetic, which makes the problem easy to underestimate.

• Long-lasting nasal discharge: often thick, cloudy, yellow or green. It frequently starts on one side and may later involve both nostrils.
• Nosebleeds: blood may appear on its own or mixed into the discharge. Any nosebleed deserves a call to your veterinarian, and a heavy nosebleed or one that will not stop needs your veterinarian or an emergency clinic right away.
• Nose pain or tenderness: your dog may pull away when the muzzle is touched, rub the face, or seem reluctant to have the head handled.
• Depigmentation of the nostril: the dark skin around the opening of the nostril may lose color and look pink, raw or crusted, usually on the affected side.
• Sneezing: frequent or forceful sneezing, sometimes bringing up discharge or blood.
• Reduced airflow: noisy breathing through the nose, or one nostril that seems blocked.
• Facial changes: in some dogs, swelling or a sunken area over the bridge of the nose or above the eyes.

Many of these signs also occur with other nasal problems, so they point toward the need for an exam rather than toward a specific cause. Our guide to runny nose and nasal discharge in dogs and cats explains how different types of discharge are assessed.

Why Chronic Nasal Discharge Needs a Workup

A dog with weeks of nasal discharge can have one of several conditions, and some are far more serious than others. Your veterinarian will consider causes such as:

• Fungal infection, including aspergillosis
• Nasal tumors, which can also cause one-sided discharge, nosebleeds and facial swelling
• Foreign material lodged in the nasal passages
• Dental disease, such as an infected upper tooth root that drains into the nose
• Inflammatory rhinitis, a nasal inflammation without a single clear trigger
• Bleeding or clotting disorders, when nosebleeds are a main feature

Because aspergillosis and nasal tumors can look so alike, reaching the right diagnosis matters greatly. You can read more about the second of these in our article on nasal tumors in dogs and cats.

How Veterinarians Diagnose Nasal Aspergillosis

No single test is perfect, so veterinarians usually combine several findings. Most of the detailed tests require general anesthesia, because the nose is sensitive and the dog must stay completely still.

1. History and physical exam: questions about when the discharge started, which side it affects and any bleeding, plus checks of nasal airflow, the face, eyes, teeth and lymph nodes.
2. Bloodwork and clotting tests: these help assess overall health before anesthesia and look for bleeding disorders, especially in dogs with nosebleeds.
3. Advanced imaging: a CT scan is often the preferred tool. It shows turbinate destruction, fungal material in the sinuses, and whether the thin plate of bone between the nose and the brain is intact, which affects which therapy is safe.
4. Rhinoscopy: a small camera is passed into the nose to look directly at the lining. Fungal plaques can often be seen as white, gray or green mats on the surface.
5. Biopsy and fungal culture: samples of the lining or plaques are examined under the microscope and cultured to confirm the fungus and rule out other diseases such as a tumor.

Your veterinarian may refer your dog to a specialty or referral hospital for CT and rhinoscopy. If you have questions about anesthesia, our article on anesthesia safety for pets covers how veterinary teams monitor patients.

Antifungal Therapy and Veterinary Care

The plan for each dog depends on how much of the nose and sinuses are involved, the CT findings, and your dog's overall health. Every medication should be given only as prescribed by your veterinarian.

Removing fungal plaques

During rhinoscopy under anesthesia, your veterinarian often removes as much fungal material and damaged tissue as possible. This step, called debridement, is considered one of the most important parts of care, because antifungal medication works best when it can reach the infected lining directly.

Topical antifungal therapy

Many dogs receive topical antifungal medication placed directly into the nasal passages and sinuses while under anesthesia. Before this is done, the CT scan is reviewed to confirm that the bone separating the nose from the brain is intact.

Systemic antifungal medication

Oral antifungal medication may be prescribed for some dogs, either alongside topical therapy or when topical therapy is not suitable. These medications are usually given over a longer course, and your veterinarian may recommend bloodwork during that time to monitor liver function and overall health.

Repeat procedures

Nasal aspergillosis can be stubborn. Your veterinarian may schedule a follow-up rhinoscopy to check whether fungal plaques remain, and some dogs need more than one round of debridement and topical therapy before the infection clears.

Long-term outlook

Many dogs respond well, though recovery can take time. The turbinates destroyed by the infection do not grow back, so some dogs keep a mild, intermittent discharge afterward. A recheck is the only way to tell this from returning fungal disease, so report any thicker, one-sided or bloody discharge.

Caring for Your Dog at Home

Home care supports your veterinarian's plan and never replaces it. These steps help your dog stay comfortable during recovery.

After nasal procedures, your veterinarian will tell you what to expect. A heavy nosebleed or one that will not stop, or any trouble breathing, needs your veterinarian or an emergency clinic right away.

When to Call Your Veterinarian

Schedule a veterinary exam soon if your dog shows gradual or milder changes, such as:

• Nasal discharge lasting longer than a few days, or one that keeps coming back
• Discharge from one nostril only
• Loss of color or crusting around the nostril
• Mild sensitivity when the muzzle is touched, or frequent face rubbing
• Frequent sneezing or noisier breathing through the nose
• Discharge returning after a course of medication has ended

Contact your veterinarian or an emergency clinic right away if your dog

• Has a heavy nosebleed or a nosebleed that will not stop
• Is struggling to breathe, breathing with the mouth open at rest, or has pale or bluish gums
• Collapses or is very weak
• Has a seizure, seems disoriented, or shows sudden changes in behavior or balance
• Shows sudden swelling of the face or around the eyes
• Has sudden changes in vision

While you arrange care for a nosebleed, keep your dog calm and quiet and do not put anything inside the nose. Our article on nosebleeds in dogs and cats explains what to do in more detail.

Common Mistakes and Myths

Myth: A runny nose in a dog is always just a cold.

Fact: long-lasting discharge, especially from one side or with blood, warrants a veterinary exam to look for causes such as fungal infection, dental disease, a foreign object or a tumor.

Mistake: Repeating antibiotics whenever the discharge returns.

Fact: antibiotics do not address a fungal infection. Discharge that improves and then returns once medication ends is a sign that a fuller workup may be needed.

Mistake: Using human nasal sprays or home remedies in a dog's nose.

Fact: products made for people can be harmful to dogs and may irritate damaged nasal tissue. Use only what your veterinarian prescribes.

Myth: Once the dog looks better, the infection is gone.

Fact: fungal plaques can remain even when signs improve. Follow-up visits and any recommended repeat rhinoscopy help confirm that the infection has truly cleared.

Frequently Asked Questions

Is nasal aspergillosis contagious to other pets or people?

It is not generally considered contagious between dogs or from dogs to people. The mold is common in the environment, and disease develops when the fungus becomes established in an individual dog's nose. If anyone in your home has a weakened immune system, they can ask their physician for personal advice.

Will my dog need anesthesia?

Usually, yes. CT, rhinoscopy, biopsy, debridement and topical antifungal therapy are generally performed under general anesthesia so they can be done safely and thoroughly.

Can nasal aspergillosis come back?

Recurrence is possible, which is why follow-up visits matter. Report any return of thick, one-sided or bloody discharge to your veterinarian.

Key Takeaways

Nasal aspergillosis is a fungal infection of the nose and sinuses caused by a common environmental mold, and it most often affects long-nosed and medium-nosed dogs. Typical signs include long-lasting discharge that often starts on one side, nosebleeds, nose pain and loss of color around the nostril. Because these signs overlap with nasal tumors, dental disease and foreign material, diagnosis usually involves CT imaging, rhinoscopy, biopsy and fungal culture under anesthesia. Care often combines removal of fungal plaques with topical or systemic antifungal medication, given as prescribed by your veterinarian, and some dogs need repeat procedures. Contact your veterinarian or an emergency clinic right away for a heavy nosebleed or one that will not stop, trouble breathing, collapse, seizures, sudden facial swelling or sudden changes in vision.