Valley Fever in Cats and Dogs

Valley Fever is a fungal infection endemic to Arizona that can affect both humans and animals. 

Valley Fever is an infection caused by a fungus (Coccidioides immitis) that is found in the soil in the southwestern United States (California, Arizona, New Mexico, Texas, and Mexico). Infection occurs when fungal spores are released from the ground after rainfall, dust storms, or construction and are carried by the wind. Once the spores are in the air, they can be inhaled and lead to infection. Valley Fever is not contagious, meaning it is not spread between animals and people. 

What are the common symptoms of Valley Fever in dogs and cats?

Many species are susceptible to Valley Fever, although dogs are more likely to be infected compared to cats. Symptoms may include:

• Fever

• Dry cough

• Decreased appetite

• Lethargy

• Limping

• Seizures

How can I tell if my pet has Valley Fever?

Blood Testing

Valley Fever is normally diagnosed through a blood antibody test. The test measures antibodies against the fungus in a blood sample. However, many animals become exposed to Valley Fever without getting sick. This means that some animals have antibodies against the Valley Fever organism without having any clinical signs. We test your dog or cat for Valley Fever antibodies if there are clinical signs consistent with the disease.

X-Rays (Radiographs)

We might also recommend x-rays (radiographs) of your pet's chest if a cough is present. Valley Fever can cause large lymph nodes and lung infiltration which will likely be found on x-rays. X-rays are also important to check for other reasons for coughing such as enlarged heart, collapsing trachea, or other respiratory illnesses. 

If your pet has unexplained limping, we might perform x-rays of the affected limb to identify radiographic changes consistent with Valley Fever or other orthopedic disorders. 

How is Valley Fever treated?

Valley Fever is treated using an oral antifungal medication such as fluconazole. Pets often need to be treated for several months to years before clearing the infection. The prognosis is better if the fungus is only in the lungs compared to systemic dissemination. Treatment continues until the clinical signs have resolved and the antibody level has stabilized.

Both the disease and treatment can impact organs such as the liver and kidneys. For this reason, it is important to monitor the pet's lab values and Valley Fever antibody levels.

Most pets with Valley Fever will eventually recover, especially if the disease is isolated to the lungs. The prognosis is worse if the disease is in multiple areas of the body such as the bones, eyes, or brain. 

How do I prevent my dog from getting Valley Fever?

At this time there is no prevention for Valley Fever. Any pet breathing Arizona air is susceptible to infection because the fungus is spread through the air from the soil. 

However, there is currently a Valley Fever vaccine being studied at the University of Arizona. The vaccine works by using a modified version of the Valley Fever fungus, delta-cps1, that results in a strong immune response without causing infection. Preliminary data shows that the vaccine is effective in protecting dogs from natural infection. The vaccine is currently undergoing safety studies in dogs to ensure there are no adverse reactions. Click here learn more about Canine Valley Fever Vaccine Project.

Other useful resources regarding Valley Fever

There are great, up-to-date resources on the University of Arizona's Valley Fever Center for Excellence. They have additional, specific information on dogs as well.