Photo by Eric Isselée.
When people think of getting an infection, what comes to mind are usually bacteria and viruses. Fungal infections also occur, although much more rarely.
Fungi have several interesting characteristics: they are ubiquitous and grow very slowly, and they occur in pockets when they cause disease. One infection caused by fungi is called aspergillosis.
Aspergillosis is a common mold that can be found throughout the environment, especially around hay, dead leaves, grain, straw, grass clippings and dust. Animals and people are exposed to it often, yet it causes an infection only when you or your pet has a problem where the immune system is weakened. This is called an opportunistic infection. This weakening can stem from a number of causes that include an inherent weakness in producing antibodies, malnutrition or parasitism.
Aspergillosis manifests itself in two different ways: the nasal version and the disseminated version. Dogs tend to get it more often than cats, with the nasal version being more common in dogs with a more elongated snout. Since farm dogs are more exposed to standing straw and hay, we tend to see the nasal version more often in them. Some breeds, the German shepherd in particular, seem to get the disseminated version.
The nasal version occurs when a dog sniffs an area with the fungal spores present, as in grass clippings. Symptoms in these pets include the following:
- Sneezing
- Bleeding from the nose
- Ulcers at the tip of the nose
- Pawing at or rubbing the nose
- Swollen nose
- Poor appetite
- Thick or pus-like discharge from the nose
- Blood or pus-like discharge from only one nostril
Fungal infections commonly go to the lungs. The mottled area throughout this radiograph is typical of a fungal infection. Photo courtesy of Long Beach Animal Hospital (LBAH).
Dogs that get disseminated aspergillosis, which means that it has spread from the nasal cavity into the rest of the body, might get the following symptoms:
- Pain when petting the spine
- Lameness
- Fever
- Weight loss
- Poor appetite
- Vomiting
Disseminated aspergillosis commonly goes to the bones of the spine, so we carefully assess this area if we suspect this disease. This is the normal spine of the lower back of a dog. Photo courtesy of LBAH.
In addition to a routine blood panel, diagnosis is assisted by use of urinalysis, a fecal exam, CT scans and radiographs. A special blood panel can look for antibodies to the fungus. A dog with a weakened immune system might not be producing these antibodies, or the antibodies could be used against a form of aspergillosis this is not pathogenic, so this test is not always diagnostic.
Analysis of any nasal discharge can be helpful. Analysis includes looking at the cells and culturing out the aspergillosis, although fungi are slow growing and culture results can take weeks or even months to determine whether there is a growth. Rhinoscopy, the insertion of a small fiber-optic scope under anesthesia, is a valuable procedure because it can find a foreign body and remove it or take a biopsy of the inner lining of the nasal cavity.
Treatment consists of antiviral medications in the nasal cavity while under anesthesia. If caught early enough and the bones of the nasal cavity are not eroded, this treatment can be effective.
Oral medication is needed for the disseminated form, although outcome varies. Once the disseminated version is diagnosed, the problem is usually too advanced to treat and is generally fatal. Treatment might be required for many months because of the slow nature of fungal infections.
For a list of other diseases and their treatments, please see the diseases page on LBAH’s website.