Valley Fever Center for Excellence


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Do Dogs Get Valley Fever?

Yes, dogs get Valley Fever! Like people, dogs are very susceptible to Valley Fever. Dogs primarily contract Valley Fever in the low desert regions of Arizona, New Mexico and southwestern Texas and the central deserts of California. Dogs accompanying people traveling through these areas or wintering in these warm climates have about the same chance as their owners of being infected.

Areas in the U.S. where the fungus is found

Dogs comprise the majority of Valley Fever cases in animals. However, other animals can get the disease as well. Cats, llamas, non-human primates, horses, zoo animals, and even wild animals have been reported with Valley Fever. For more information on Valley Fever in other species, go to Valley Fever in Other Animal Species.

Used with permission: Dr. H. Levine

Valley Fever is caused by a fungus that lives in the desert soil in the areas described above. As part of its life cycle, the fungus grows in the soil (saprophytic cycle) and matures, drying into fragile strands of cells. The strands are very delicate, and when the soil is disturbed - by digging, walking, construction, high winds - the strands break apart into tiny individual spores called arthroconidia or arthrospores. Dogs and people acquire Valley Fever by inhaling these fungal spores in the dust raised by the disturbance. The dog may inhale only a few spores or many hundreds.

Once inhaled, the spores grow into spherules (parasitic cycle) which continue to enlarge until they burst, releasing hundreds of endospores. Each endospore can grow into a new spherule, spreading the infection in the lungs until the dog's immune system surrounds and destroys it. The sickness Valley Fever occurs when the immune system does not kill the spherules and endospores quickly and they continue to spread in the lungs and sometimes throughout the animal's body.

About 70% of dogs who inhale Valley Fever spores control the infection and do not become sick. These dogs are asymptomatic. The remainder develop disease, which can range from very mild to severe and occasionally fatal.

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