Valley Fever: Dogs can get it, too (and do!)

It was a typical Valley summer: monsoon rains, extremely hot temperatures and terrific dust storms. September turned mild, and Daisy, the boxer, resumed her passion for rolling in the dirt and digging for imaginary rabbits.

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She began coughing and fatigued easily, sometimes became short of breath and stumbled. She ignored her food, even her favorite sausage treats, and lost weight. When petted, she squirmed in pain. Her forehead was often hot, suggesting fever. She developed a rash and stiff neck.

Taken to the vet, her blood was drawn and a cocci titer ordered. Soon the report came. Daisy had Coccidioidomycosis. Valley Fever.

Daisy’s veterinarian ordered Fluconazole (Diflucan), currently the best treatment, and scheduled liver tests.

Prevalent in Maricopa, Pinal and Pima counties, Valley Fever is caused by the microscopic fungus, Coccidioides spp., in areas with little rainfall, high summer and mild winter temperatures. It remains dormant until rain causes it to grow, sending out fragile, spore-filled strands. These become brittle in high temperatures, easily disturbed by construction and farming, even the curious sniffing of a dog. The fungal spores become airborne and potentially deadly when inhaled.

A parasitic cycle begins, with the spores growing, bursting and spreading infection in the lungs. If the immune system does not destroy it, sickness occurs and the spores multiply, with symptoms like those shown by Daisy.

Thomas Gus, DVM, Medical Director of University Animal Hospital in Tempe, said, “Although the lungs are the most common site of Valley Fever, it can infect almost any tissue. Bones are also affected, causing lameness.”

Every year, according to the University of Arizona, an estimated 150,000 infections occur in humans and more than 60,000 in dogs. Approximately 60 percent of the infections are mild and 30% are moderate, with recovery generally giving immunity. Another 10 percent are severe, possibly lethal, cases. About two-thirds of the reported cases occur in the “Valley Fever corridor,” the area between metro Tucson and metro Phoenix.

Gus said not only residents, but “visitors, with practically their first breath, are potentially exposed to Valley Fever. When those visitors and pets return home, say to the Northeast, many vets there aren’t sensitive to the disease and may take longer to reach a definitive diagnosis.”

Because of its geographically restricted area, Valley Fever is called an “orphan disease,” receiving little federal attention or funding, although millions of Arizonans and their animals are exposed to this potentially deadly disease. The UA’s Valley Fever Center for Excellence is the only research institution in this hyper-endemic area and relies heavily upon private funding.

Lisa Shubitz, DVM, a UA professor and prominent VFCE researcher, spoke recently to Phoenix-area veterinarians. She described her research, advancing a potential canine vaccine, which becomes “the pathway for a vaccine for humans.”

That promising development, originated by Dr. Marc Orbach, UA professor in Plant Sciences and a fungal geneticist, involves a mutant strain of the coccidioides fungus, created by “knocking out” a disease-causing gene. The mutant strain is injected into laboratory mice that lack immune systems. Then the mice are challenged with the pathogenic strain. The mutant strain protects nearly all tested mice from lethal doses.

Before the potential vaccine can be tested in dogs, more lab tests and the development of product stabilizers are necessary. Then Shubitz can perform testing to meet USDA regulations and licensing requirements.

It will cost over $2 million, but will save thousands of Arizona dogs and more than $60,000 in their annual treatment costs. The science can then be transferred to develop the human vaccine. Shubitz smiled, showed her crossed fingers, “I’m hoping for an angel. A benefactor.”

Richard Stolper, DVM, of Scottsdale Ranch Animal Hospital, attended the lecture and sees infections tied to the cycle of monsoons and dust storms. “If your dog hasn’t had Valley Fever,” he said, “it’s only a matter of time until it’s exposed. Know the warning signs. Take it to your veterinarian if you suspect anything. The earlier you start treatment, the more likely you’ll have a better outcome.”

Dr. Gus confirmed the need for early diagnosis, adding that large dogs are especially susceptible to the disease, “probably because they’re outdoors more. Hunters and hounds. And breeds with short muzzles, like pugs and boxers.”

He stressed that pets showing respiratory symptoms and lameness should be checked for Valley Fever.

As a final caution, Gus said, “If there’s a dust storm, protect yourself and your pets. Stay inside.”

Curious about Daisy? She eventually recovered. Her owner spread gravel and planted grass over Daisy’s favorite “digs.” Since Valley Fever can recur, Daisy stays inside during dust storms, with plenty of her favorite sausage treats.

For information about UA’s Valley Fever Center for Excellence, or to make a donation, visit www.vfce.arizona.edu. Follow the canine vaccine development on Facebook.

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