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Valley Fever in Dogs: Everything You Need to Know

Valley Fever is a well-known concern for those residing in the southwestern United States. However, understanding the prevalence and severity of this disease in dogs is crucial for pet owners in the region. Whether you’re a resident or planning a visit to this area, it’s essential to educate yourself about Valley Fever to safeguard your canine companions. Below is your comprehensive overview of Valley Fever in dogs.

What Is Valley Fever?

Valley Fever stems from an infection caused by the fungus Coccidiodes immitis. It’s also known by various names such as coccidioidomycosis, California disease, desert rheumatism, or San Joaquin Valley Fever. The disease is prevalent in south-central Arizona and frequently detected in other areas of Arizona, as well as in desert regions of New Mexico, southwestern Texas, California, Nevada, and Utah. Additionally, parts of Mexico and Central and South America are affected. While humans and dogs are the most commonly diagnosed with Valley Fever, it can also infect various mammals, including cats.

What Causes Valley Fever in Dogs?

Valley Fever in dogs is caused by Coccidiodes organisms found in desert soils. These organisms generate lengthy mold filaments containing infectious spores. Disturbances like digging by dogs, construction activities, or windstorms can propel these spores into the air, where they can be inhaled. Upon inhalation, the spores transform into a yeast-like organism that infects the lungs. In Pima, Pinal, and Maricopa counties in Arizona, approximately 6–10% of dogs are diagnosed with Valley Fever annually. The high frequency of Valley Fever diagnoses in dogs is attributed to their common habit of disturbing and sniffing dirt during their daily activities.

Is Valley Fever Contagious?

Valley Fever is not contagious, so if your dog contracts the disease, there’s no risk of them spreading it to you or other pets. The transmission of Valley Fever occurs through inhaling spores found in dirt and dust, not through contact with an infected animal or person. In Pima, Pinal, and Maricopa counties in Arizona, approximately 6–10% of dogs are diagnosed with Valley Fever annually.


While many dogs exposed to Coccidiodes immitis may not exhibit symptoms of illness, their immune systems can typically contain and eradicate the organisms before they proliferate and cause Valley Fever. However, when a dog encounters a substantial number of spores or has a compromised immune system, Valley Fever can manifest. Common symptoms of a lung-limited infection include coughing, lethargy, fever, poor appetite, and weight loss. If the infection spreads beyond the lungs, additional symptoms may arise, such as back or neck pain, lameness, seizures, abscesses, slow-healing skin wounds, swollen lymph nodes, eye abnormalities, heart failure, or blindness. In Arizona, the highest risk of exposure to Coccidiodes immitis appears during the drier months of June, July, October, and November, though this may vary in other regions. Symptoms of infection can surface weeks, months, or even years after exposure.


Veterinarians practicing in regions where Valley Fever is prevalent are well-versed in the disease and routinely conduct tests on dogs exhibiting typical symptoms. If you’ve recently visited or relocated from an area where Valley Fever is common and your dog is showing signs of illness, it’s imperative to inform your veterinarian about your dog’s travel history. You should also inquire whether a Valley Fever test should be administered.

The primary method for testing Valley Fever is through a titer, which measures the level of antibodies against Coccidiodes present in a blood sample. Essentially, a titer test reveals whether a dog has been exposed to Coccidiodes. Veterinarians analyze the titer results along with other diagnostic tests like complete blood cell counts, blood chemistry panels, X-rays, and the dog’s symptoms and history to ascertain whether the dog has Valley Fever. In complex cases, additional tests may be utilized to aid in diagnosis.


Dogs diagnosed with Valley Fever receive anti-fungal medications designed to inhibit the growth of Coccidiodes organisms and empower the dog’s immune system to manage—and ideally eliminate—the infection. Commonly prescribed medications include Fluconazole, Itraconazole, and Ketoconazole. In cases of severe infections or when traditional treatments prove ineffective, veterinarians may explore alternative options. Additionally, veterinarians may recommend anti-inflammatory drugs, pain relievers, nutritional support, fluid therapy, and other treatments tailored to the individual needs of the dog.

Treatment for Valley Fever is prolonged, typically lasting from six months to a year. Some dogs may require extended or even lifelong treatment to prevent relapses. Veterinarians determine the optimal time to discontinue anti-fungal medications based on the dog’s response to treatment and follow-up testing, closely monitoring for any signs of relapse.

Survival Rate for Dogs With Valley Fever

According to the University of Arizona, over 90% of dogs treated for Valley Fever will survive. However, dogs with symptoms affecting multiple parts of the body, especially the brain, or those that exhibit poor response to anti-fungal medication, have a less favorable prognosis. Despite appropriate treatment, relapses are frequent, underscoring the importance of vigilant monitoring. Generally, dogs experiencing relapses typically respond well to treatment but may require lifelong administration of antifungal medication to manage the condition effectively.

How To Prevent Valley Fever in Dogs

To safeguard your dog’s health in a Valley Fever endemic area, it’s essential to take preventive measures. Minimize your dog’s exposure to soils and airborne dust by keeping them indoors whenever possible. When outside, ensure your dog is on a leash and walk them on paved sidewalks. These precautions can significantly reduce the risk of your dog contracting Valley Fever.

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