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Nasal Fungus In a Dog (Sinonasal Aspergillosis)

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The owners of an adult male neutered German Shepherd noticed that their dog had experienced occasional bleeding from the nose and sneezing for about a month. The primary care veterinarian thoroughly examined the dog and performed blood tests and skull radiographs

The owners of an adult male neutered German Shepherd noticed that their dog had experienced occasional bleeding from the nose and sneezing for about a month. The primary care veterinarian thoroughly examined the dog and performed blood tests and skull radiographs. The blood tests were all normal and the X-rays revealed increased thickness in nasal tissue and damage to the back of the left nasal passages. The dog was treated with an oral antibiotic. The bleeding stopped, but the sneezing continued. At the follow-up visit after finishing the antibiotic treatment the examination revealed occasional nose bleeding, good airflow, no nasal discharge, and no discoloration to the tip of the nose. At this point the dog was referred to a veterinary specialist for evaluation and advanced diagnostics. 

At the specialty hospital a CT scan showed several areas of bone loss within the left nasal cavity with irregular soft tissue of outside origin on the walls of the remaining bone. Similar material was seen in the front left sinus. There was mild bone loss in the right nasal sinus, but no abnormal soft tissue was noted. The roof of the sinuses was found intact and the lymph nodes on the left side of the dog’s head were swollen.

When a camera was placed down the dog’s nose to investigate the nasal cavities, the right nasal cavity was found normal; however, the left nasal cavity showed thick mucus. The left nasal cavity was inflamed and showed bone destruction along with fungal plaque at the entrance of the front sinus. The plaque found was tested, then removed.

The test on the fungal plaque was performed at the veterinary specialty hospital during the procedure; it revealed the mold Aspergillus. This new development produced a diagnosis of sinonasal aspergillosis.

Sinonasal aspergillosis is the second most common cause of nasal discharge in dogs, and affects primarily dogs that are male, long-nosed, and young to middle aged. It is most often caused by the fungus Aspergillus fumigatus, but sometimes other fungi, such as Penicillium. In most cases, it involves the nasal cavity and the front sinuses.

Aspergillus is a fungal organism found in many places and is a common mold. It also infects humans, mammals, birds, and reptiles, in which it most often causes respiratory disease in animals with compromised immune systems.

Dogs with sinonasal aspergillosis are thought to have local immune system dysfunction, but most seem immune-competent. In some cases, there is an underlying condition, such as a foreign body, a cancerous tumor or trauma. A rare form of Asperillus, Aspergillus terreus, occurs in German Shepherds thought to have immune deficiencies.

In sinonasal aspergillosis, the fungus is non-invasive, but produces toxins that kill tissue, which can lead to a severe inflammatory host response, causing destruction to bones. Clinical signs include pain; nasal discharge; nosebleed (from either one nostril or two); loss of appetite; ulcers on the nose; change in color of the nose; increased nasal airflow; facial deformity; or excessive tearing.

Sinonasal aspergillosis can be diagnosed by: 1) history and clinical signs, 2) skull X-rays or CT (CT provides more information), or 3) rhinoscopy with visualization of fungal plaques or fungal characteristics noted on cytology or histopathology of nasal or sinus mucosal biopsy.


Antifungal medications have poor to moderate response rates (50 – 70% success rate), are expensive and require long-time dosing. In addition, antifungal medications have potential side effects such as liver damage and gastrointestinal problems.

Topical antifungal treatments, such as clotrimazole or enilconazole have up to an 85% success rate when properly infused into the nasal cavities. These types of medications cause direct-damage to fungal membranes therefore killing the fungal organisms and allowing the immune system to clear the debris. A single one-hour infusion will cure about 50% of dogs, the rest will need two to three (or more) treatments. Multiple treatments and recheck rhinoscopy will be recommended weekly to monthly based on the needs of the patient and owners. Treatments are usually continued until two consecutive rhinoscopy procedures have failed to find additional fungal plaques.

Fortunately, the dog’s owners elected infusion treatment.



After infusion treatment (such as with clotrimazole): the dog was monitored overnight in the hospital for aspiration, coughing, and respiratory distress; and for pain management and/or anti-inflammatory medications. As expected the dog’s nose continued to have a discharge for five to seven days after the infusion. The specialist rechecked the dog with a rhinoscopy and followed up with another infusion four weeks later. Infusion complications can include scar tissue, chronic obstructive sinusitis, lesions (rare), aspiration pneumonia, chronic nasal discharge, and reoccurrence of fungal infection. Fortunately, this dog recovered uneventfully; he and his owners are delighted.


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