Valley Fever in Dogs: An Overview
Dog Breeds
>“Valley Fever” is a common term for coccidioidomycosis, which is an uncommon but extremely severe and potentially fatal systemic disease caused by Coccidioides immitis.
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Definition
“Valley Fever” is a common term for coccidioidomycosis, which is an uncommon but extremely severe and potentially fatal systemic disease caused by Coccidioides immitis. This fungus thrives in the hot, dry, dusty areas of the deep southwestern United States – especially in Arizona, California and Texas. It also exists in Mexico and in parts of Central and South America. Not all dogs exposed to the fungi succumb to clinical disease, but many do. People can also become infected with this organism.
Causes of Valley Fever in Dogs
Valley Fever is caused by inhalation of the infectious form of the dimorphic fungus, Coccidioides immitis. This fungus has a mycelial form and a yeast form. The mycelial form persists naturally several inches deep in the soil of endemic areas. It is dormant during periods of drought. After rainfall, earthquakes, excavation or other causes of soil disturbance, the mycelial fungi surface, sporulate and become airborne. The released spores, called arthroconidia, are highly infectious and easily inhaled.
The arthroconidia invade deep portions of the dog’s respiratory tract, where they change into the organism’s yeast form. The yeast form of the fungus produces endospores, which can spread throughout the dog’s body and lodge in distant tissues. It takes several weeks after inhalation of arthroconidia for symptoms of respiratory infection to develop. It can take months for signs of disseminated infection to develop.
Prevention of Valley Fever
No vaccine is currently available for Valley Fever. The disease cannot develop unless a dog has lived in or traveled through a region where the fungal organism is endemic. Contaminated soil in endemic areas – especially during dust or wind storms after rain – should be avoided.
Special Notes
Coccidioidomycosis occurs in people as well as in dogs. Owners can become infected by the fungi at the same source as their dogs. Valley Fever is not considered to be contagious. It is extremely unlikely that people can contract infection from dogs, or that people can cause infection in their pets.
Valley Fever usually can be treated, if the fungal infection is promptly and properly diagnosed. However, successful treatment can take months to years to complete.
Causes of Valley Fever in Dogs