Treatment and Prognosis for Valley Fever in Dogs
Valley Fever, medically called coccidioidomycosis, is a potentially fatal fungal disease in domestic dogs. Successful treatment is possible if the infection is properly and promptly diagnosed. However, treatment can take more than one year to complete. The goals of treating this disease are to prevent further dissemination of the fungal organism, eradicate the fungi from the dog’s body and restore the dog’s quality of life.
Most dogs with Valley Fever are treated as outpatients. Supportive care for these dogs includes restricting their activity until clinical signs of the infection resolve. Dogs should be fed a high quality, extremely palatable diet with free access to fresh water. If necessary, patients can be hospitalized and provided with oxygen supplementation.
Diagnosis of Valley Fever should be rapidly followed by oral anti-fungal therapy. The anti-fungal drugs currently available are in the imidazole, or “azole,” pharmaceutical group. They include itraconazole, ketoconazole and fluconazole, although of course with time newer medications may become available. Ketoconazole can be effective and is the least costly, but it carries the risk of more adverse side effects, including liver damage, vomiting and loss of appetite. Itraconazole is more expensive than ketoconazole and may or may not have fewer side effects. Fluconazole has the best penetration of the eye and central nervous system and is the most commonly used anti-fungal drug, although it is costly. Amphotericin B is another highly-effective anti-fungal medication that can be used when a dog does not tolerate or respond well to treatment with the azole drugs. It can also be used in combination with an azole drug. However, Amphotericin B is highly nephrotoxic and can cause significant kidney damage. An even newer drug, Lufenuron, has shown promising results in the treatment of disseminated coccidioidomycosis in dogs.
Whichever anti-fungal medications are chosen, they must be administered precisely in accordance with a veterinarian’s directions. This will typically be twice a day, for at least six to twelve months, and maybe longer. Medical therapy must continue for several months after the dog’s symptoms have resolved, so that long-term suppression of the fungus can be achieved. Anti-fungal medications can be toxic to dogs. They can cause liver dysfunction, kidney damage, gastrointestinal upset and adverse skin reactions, and they require close medical management. Blood testing every 3 to 4 months after completion of drug therapy is recommended to monitor progress. Unfortunately, relapses are common.
The prognosis for dogs that only develop respiratory signs of Valley Fever is fair to good. Sadly, the prognosis for dogs with disseminated systemic disease is guarded to grave.