Dog Aspergillosis is a fungal infection that invades the respiratory system, ears, throat and mouth. Dogs can inhale fungi spores or “conidia” naturally present in the environment, such as in straw, grass or grain. Common species are Aspergillus fumigatus and Aspergillus tereus. The Aspergillus fungi develop in tissue and lead to cell death and formation of abscesses. Younger dogs under 7 years may suffer from two types of Aspergillus infection: Nasal Aspergillosis or Disseminated Aspergillosis. Breeds with medium and long noses, including German Shepherd Dogs, Labrador Retrievers and Rottweilers, seem more prone to this infection that affects dogs with poor or deficient immune systems. Dogs that sniff in areas with fungal contamination may also be affected.
Symptoms and Diagnosis
Symptoms of Nasal Aspergillosis include nasal discharge, often odorous, and nose bleeds. Ulcerations may appear on the external part of the nose, at the edges of the nostrils. Dogs may experience pain or discomfort in the nose or facial region. This invasive infection destroys the bones of the sinuses. Symptoms of Disseminated Aspergillosis include bone infection. Which part of the body the fungus infects can determine the symptoms. The fungus invades the respiratory tracts or other organs through the bloodstream. The fungi may also attack the intervertebral discs of the spine. Common signs include weakness, uveitis (deep inflammation of the eye), fever, lameness, draining tracts, appetite loss and other symptoms that often show too late in a systemic disease. German Shepherd Dogs may be more prone to Disseminated Aspergillosis.
Diagnosis may be from two of the following criteria: radio graphs, fungal plaques, tissue biopsy or nasal discharge, or a blood test that is positive for antibodies. X-rays may reveal bone destruction patterns. Problems with antibody tests include knowing what species of Aspergillus to test.
Treatment of Dog Aspergillosis may be topical or systemic. Topical treatment requires infusion into the sinus cavities. Under general anaesthesia, the dog’s throat is closed at the back with gauze and foley catheters. The topical antifungal agent of 60 ml of 1% clotrimazole solution infuses the nose and frontal sinuses under pressure. After the incubation period, the clotrimazole is drained and suctioned. Some patients require long periods of treatment sessions. More promising is the combination of clotrimazole irrigation and depot therapy that allows a shorter treatment and lower patient morbidity. This process includes a five-minute flushing of 1% topical clotrimazole solution, then an application of 1% clotrimazole cream as a deposit agent into the frontal sinuses. After removal of the catheters, the skin incisions are closed. After the excess fluid drains, then the gauze is removed. This treatment has a success rate of 86%.
Systemic treatment includes oral antifungal drugs such as itraconazole or fluconazole. Surgical treatment is an extreme resort.
Treating Disseminated Aspergillosis may include the older antifungal drug Amphotericin B that carries the risk of causing kidney damage. Newer drugs may not cause as much damage, yet may not be as an effective treatment. Several years of itraconazole may be of benefit.