Valley Fever (i.e., coccidioidomycosis) most commonly affects pets in alkaline desert regions in Arizona, New Mexico, southwestern Texas, and central California. Cases have also been reported in Washington, Oregon, Utah, Nevada, and desert areas in Central and South America. While dogs seem especially susceptible, cats can also be infected with the disease, which can potentially cause significant health complications for affected pets. Our Southern Arizona Veterinary Specialty and Emergency Center team wants to help by providing information about Valley Fever in case your pet contracts the disease.  

The basics about Valley Fever in pets

Valley Fever is caused by inhaling dust or dirt contaminated by fungi in the Coccidioides genus, and was named after an outbreak among San Joaquin Valley, California, farm workers. The fungus lives in sandy, alkaline areas that have little rainfall, hot summers, and cold winters. After a rainfall, fungal spores (i.e., arthroconidia) are released from the ground and carried by the wind, and earthquakes, high winds, and crop harvesting have led to Valley Fever outbreaks that affect animals and humans. About 60% of animals and humans who are infected by Valley Fever don’t get sick, but those who exhibit signs typically become ill about one to three weeks after inhaling the fungal spores. Signs tend to differ in cats and dogs:

  • Valley Fever signs in dogs — Dogs are more commonly affected by the disease, likely because they tend to sniff the ground and dig in the dirt. Signs include coughing, fever, weight loss, decreased appetite, and lethargy. If the infection disseminates (i.e., spreads outside the lungs), signs can include lameness, swollen lymph nodes, back or neck pain, eye inflammation, swollen testicles, skin lesions, and heart failure.
  • Valley Fever signs in cats — The most common sign in cats is non-healing skin lesions that look like abscesses, draining tracts, or dermatitis. Other signs can include fever, weight loss, decreased appetite, and difficulty breathing.

Valley Fever diagnosis in pets

Tests that help Valley Fever diagnosis in pets include:

  • X-rays — Pets with Valley Fever typically exhibit lung lesions and enlarged lymph nodes, and chest X-rays can help rule out other conditions, such as heart disease and tracheal collapse, that may cause your pet to cough. If your pet is lame, an X-ray of the affected area may also be helpful.
  • Blood testing — Blood tests can test for antibodies against the fungus. Antigen tests are also available that test for proteins on the fungus.
  • Biopsy — Biopsying non-healing wounds can detect the fungus in infected tissue.
  • Tracheal wash — Lung fluid can be collected by tracheal wash to test for the fungus.

Valley Fever treatment in pets

Treating Valley Fever is typically a lengthy process that must continue until the clinical signs resolve, X-rays appear normal, and antibody levels stabilize. Treatment usually involves:

  • Antifungals — Antifungal medications are typically prescribed for 6 to 12 months or longer. These medications can be toxic to the liver, so your pet will need periodic blood tests to monitor their liver function. 
  • Cough suppressants — If your pet has a severe cough, our veterinary team may prescribe a cough suppressant.
  • Pain and fever medications — Non-steroidal anti-inflammatories (NSAIDs) or other pain medications may improve your pet’s attitude and appetite during severe disease stages. 
  • Intravenous (IV) fluids — Severely affected pets may require hospitalization to receive IV fluids to help prevent dehydration. 
  • Nutritional support — Nausea and vomiting are common side effects of many antifungal medications, and your pet may require hand feeding, a feeding tube, or medication to reduce these signs and help stimulate their appetite. 

Valley Fever prognosis in pets

Your pet’s prognosis depends on several factors, including:

  • Infection severity and location — Mild to moderate infections that affect only the lungs have the best prognosis for full recovery. Pets who have disseminated infections may need prolonged drug treatment, and some pets require medication for life. Pets whose infection disseminates to the brain usually carry a guarded prognosis, and they typically need anti-seizure medications and steroids to control brain swelling. In some severe cases, pets don’t respond or respond poorly to treatment, and their condition progresses despite medication.
  • Medication administration — Many pets show improvement after one to two weeks of treatment, but you must continue treatment as prescribed by your veterinarian to help prevent recurrence. Your pet will likely need several rechecks before their treatment can be stopped.
  • Relapse — Valley Fever relapse is common after stopping treatment, and you should monitor your pet closely for any signs indicating that the infection may have returned.  

Valley Fever prevention in pets

Not every Valley Fever infection can be prevented, but you can take steps to decrease your pet’s risk, including:

  • Keeping your pet indoors — Keep your pet indoors as much as possible so they aren’t exposed to the fungi.
  • Reducing dust — Plant grass or cover your yard in deep gravel to help reduce dust.
  • Preventing digging behavior — Prevent your dog from sniffing and digging in sandy or dusty areas. 

Valley Fever is a concerning disease that can cause significant health complications for your pet, but you can take steps to reduce their risk. If your veterinarian suspects your pet has Valley Fever, contact our Southern Arizona Veterinary Specialty and Emergency Center, so we can determine the best treatment strategy for your pet.