Fungal nasal disease

Fungal nasal disease is most commonly seen in young, long-nosed dogs such as German Shepherd Dogs and Golden Retrievers. Males seem to be at more risk than females. The fungal spores are widely found in the soil and are sniffed into the nose when the dog is out. Most dogs are able to remove the spores from their respiratory tract but in some dogs, this does not happen and the spores are able to develop into fungal plaques.

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The most common fungus causing fungal nasal infection is Aspergillus fumigatus. This fungus is found worldwide in the environment and is usually associated with decaying vegetation, compost, moldy hay etc. It is not clear why some dogs develop disease when most dogs must be exposed to the fungus in their environment. It is thought that rhinitis, inhalation of grass awns, or trauma may damage the nose and/or predispose some animals to developing infection. However, the disease is not uncommon and may be seen in dogs in with no previous history or identifiable risk factors.

Dogs with nasal aspergillosis can have a range of clinical signs that most commonly includes a cream or greenish nasal discharge and sneezing. In some cases, loss of pigment or tissue on the surface of the skin may also occur and nose bleeds may be a feature. With time swelling and pain over the nose and bleeding from the nostril may develop. Affected dogs may be depressed and unwilling to eat. Less commonly the degree of infection and inflammation in the nose can be severe and extend to involve adjacent structures such as the eyes or the brain. This can cause changes to vision or even seizures in some dogs.

Your veterinarian may suspect what is wrong with your pet from the signs they are showing. However, they will need to do further tests to confirm the diagnosis and rule out other possible causes. These tests are likely to include X-rays (or an MRI or CT scan) of your dog’s head and possibly putting an endoscope (camera examination) into your dog’s nose to take some tissue samples to look and try and grow the fungus. These procedures will require a general anesthetic.

A blood test is available but, it is important to remember that this test is not 100% accurate and some unaffected dogs may be diagnosed as positive and some infected dogs may test negative.

The treatment for nasal fungal infections is not straightforward and a variety of options are available. Most commonly, effective treatment strategies for the fungal infection are aimed at removing as much of the infection as possible under anesthetic (debridement), before applying liquid or cream anti-fungal agents directly to the site of infection. Debridement is usually achievable in most cases via a minimally invasive endoscope procedure. Often, multiple topical treatments are needed to completely cure the infection, and this can mean that multiple anesthetics are required. Overnight hospitalization for monitoring may be needed during recovery from this procedure.

Some cases with more extensive disease can require surgical treatment, and more prolonged stays in hospital.

In some cases, anti-fungal tablets are also prescribed following topical therapy, or these may be the main treatment recommended for those cases with extensive infection and involvement of the brain where use of topical antifungal agents are considered too risky, and surgery is not considered a good option by the treating veterinarian or owner.

These anti-fungal tablets are generally very well tolerated, but approximately 10% of dogs may have side effects with treatment and therefore monitoring with regular clinical assessments and blood tests to check liver function are usually recommended; depending upon the combination of tablets prescribed.

Nasal discharge may be worse immediately after topical treatment, but often improves within 2-3 weeks of topical therapy for nasal aspergillosis. It may be necessary to examine the nose again using an endoscope approximately 2 weeks after therapy to check that the fungus has been treated successfully. If discharge persists, or where there is any suspicion of ongoing infection with reassessment, a second treatment is often recommended.

Resolution of clinical signs is one of the best indicators of response to treatment and the outcome is good in many cases. However, if the fungal disease has spread into the eye or brain then treatment options may be more limited and the longer term outlook may be poorer. Once the infection has been cleared it is not likely that it will recur, although relapses or repeated infections have occasionally been reported.

The fungal spores that cause Aspergillus infection are present throughout the environment so every person and all pets will normally be exposed to them. Importantly, most people and animals do not become infected and nasal aspergillosis is not considered contagious.

Standard hygiene measures, washing your hands after contact with your pet and cleaning up nasal discharge, will reduce contamination of the environment. It would be wise to take special precautions with an infected animal, and consult your doctor, if there are individuals in the household that have a compromised immune system due to disease, certain medications and very old or very young age.

Since the spores are present throughout the environment there is really no way to prevent your dog coming into contact with them. It is important to remember that the vast majority of dogs exposed to environmental aspergillosis never develop a problem despite sniffing around in the soil every day. Prompt consultation with your veterinarian if there are signs of a persistent nose discharge, sneezing or nose bleeds can help identify disease early and improve the success of treatment.