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Valley Fever


What is it?
Valley Fever (also called Coccidiodomycosis) is a disease caused by a fungal spore that is inhaled from the environment.  The spore survives in the warm, arid climates of the deserts of the southwestern United States. The disease occurs in most domestic animal species, many exotic species and in man.  It is not contagious from animal to animal or animal to man, or man-to-man, or man to animal. There are two forms of the disease – the primary form and the disseminated form.  The primary form develops two to four weeks after exposure, and is primarily located in the lungs and thoracic lymph nodes.  In the disseminated form the disease has spread beyond the lungs to other areas of the body, such as the bones, joints, brain or any other organs.

In the primary form of the disease signs may include an elevated temperature, listlessness, anorexia and a dry, harsh cough.  In the disseminated form of the disease signs may include lameness, weight loss, chronic cough, pain, skin abscesses, incoordination, or seizures.

The diagnosis for valley fever may involve a physical examination, radiographs of the chest or affected limb, blood serology testing and some other specialized testing as indicated by the signs (such as a CT scan for seizures).

The treatment for valley fever should be started immediately.  If done so, we can often prevent the primary form from becoming the disseminated form.  Several antifungal drugs can be used. The most effective oral drugs are Fluconazole (Diflucan) and Itraconazole (Sporonox). These drugs also have the least side effects.  They are used for both forms of the disease. Ketoconazole (Nizoral) is also used, and is less expensive than the other two drugs mentioned, but has been associated with the side effects of loss of appetite, vomiting, lightening of the hair coat and even liver toxicity. Occasionally, extremely ill patients might need to be hospitalized and treated with an intravenous infusion of Amphotericin B, which may need to be repeated over several weeks. Depending on the patient’s clinical signs, we may use additional drugs, such as anti-vomiting drugs, painkillers, antibiotics and seizure-control drugs.  We like to monitor our patients by reevaluating them at least every 4-8 weeks, and performing repeat blood serology tests and perhaps follow-up radiographs.

At this time, there is no known prevention of valley fever.  However, reducing your pet’s exposure to the desert soil and dust as much as possible may help.  It appears that areas with a lot of construction may have a higher incidence of valley fever spores in the environment. There is no vaccine available.