Valley Fever is a fungal disease caused by the organism Coccidioides immitis. This organism lives in the dry alkaline soil which is found in the Sonoran desert areas of the southwestern U.S. It is also found in Central America and the Middle East. When the soil is disturbed from building, gardening or strong winds, spores are released into the air. The disease is transmitted by inhalation of the spores, not by contact. Valley Fever was originally diagnosed in a group of farm workers in the San Juaquin Valley of California.
A few weeks ago, the Phoenix area experienced strong winds that lasted several days. Now, I am seeing a spike in Valley Fever cases in dogs. One of the newly diagnosed cases was in my own dog! A week ago, he came to me in the middle of the night. He was shaking and holding his neck in a strange position. When I tried to move it, he yelped. I gave him some medication for pain and then held him until he fell asleep. Three days later, a blood test confirmed the diagnosis of coccidioidomycosis (Valley Fever).
Clinical signs of Valley Fever vary greatly. Most exposed animals and people get mild flu-like symptoms of aches, chills and a dry cough which resolve after a few days. Forty percent of the exposed animals and people become sick. The fungus can settle anywhere in the body. In humans, the lungs are the most common site. In dogs, I have seen Valley Fever affect almost every organ in the body. Here is a list of the more common sites I see in dogs:
1) Lungs causing pneumonia characterized coughing.
2) Brain causing seizures.
3) Bone and joints causing lameness and arthritis.
4) Eyes causing anterior uveitis.
5) Spinal cord causing pain and problems walking.
6) Internal organs such as liver and kidney. Blood work reveals elevated enzymes associated with the affected organ.
Since most of the cats in my area are kept indoors, I rarely see Valley Fever in this species. When I do, the cat usually presents with fever, weight loss and a skin lesion.
When I started practicing in Arizona, a wise veterinarian told me, “If a pet sneezes, check it for Valley Fever.” It was great advice!
-Brooks, Wendy. Valley Fever (Coccidioidomycosis), The Pet Health Library, VIN Published 9/26/07 and reviewed in 12/1/09.