Valley Fever in Dogs: Symptoms, Treatment & Regional Risk

Quick Answer
  • Valley fever, also called coccidioidomycosis or "cocci," is a fungal infection dogs get by inhaling Coccidioides spores from dusty soil in the desert Southwest, especially Arizona and parts of California, New Mexico, Nevada, Utah, and west Texas.
  • Many exposed dogs never get sick, but dogs that do can develop cough, fever, tiredness, poor appetite, and weight loss. If the infection spreads beyond the lungs, limping, bone pain, eye inflammation, skin sores, or neurologic signs can occur.
  • Diagnosis usually combines travel or regional history with a valley fever blood test, chest X-rays, and sometimes imaging or sampling of affected tissue. A negative early test does not always rule it out, so your vet may recommend repeat testing.
  • Treatment usually means months of antifungal medication. Fluconazole is commonly used because it is widely available and reaches the eyes and nervous system well, but itraconazole, amphotericin B, terbinafine combinations, or newer antifungals may be considered in some cases.
Estimated cost: $350–$1,200

What Is Valley Fever?

Valley fever is a fungal infection caused by Coccidioides organisms that live in dry, dusty soil. Dogs become infected when they inhale airborne spores after wind, digging, construction, or other soil disturbance. It is not spread from dog to dog, and people do not catch valley fever from routine contact with an infected dog.

In dogs, the infection usually starts in the lungs. Some dogs clear or contain the infection without obvious illness. Others develop a primary lung infection with cough, fever, low energy, and weight loss. In more serious cases, the fungus spreads through the body. This is called disseminated valley fever.

Disseminated disease often affects bones, joints, lymph nodes, skin, and eyes. Bone involvement is especially important in dogs because it can look like an orthopedic injury at first. Rarely, the brain or spinal cord is affected, which can lead to seizures, neck pain, back pain, or behavior changes.

Dogs are considered one of the animal species most likely to develop clinical illness from this fungus. That is one reason your vet may think about valley fever quickly if your dog lives in, or has traveled to, the Southwest and has a chronic cough or unexplained lameness.

Signs of Valley Fever in Dogs

  • Persistent cough, often dry or harsh - common with primary lung infection
  • Fever - may be intermittent and easy to miss at home
  • Lethargy or exercise intolerance - common early sign
  • Decreased appetite and gradual weight loss - often develops over days to weeks
  • Lameness, limping, or shifting leg pain - concerning for spread to bone or joints
  • Swollen, painful joints - can mimic injury or arthritis
  • Enlarged lymph nodes - may be found on exam or imaging
  • Draining skin tracts, nodules, or nonhealing sores - possible skin dissemination
  • Eye redness, squinting, cloudiness, or vision changes - urgent because ocular disease can threaten sight
  • Back pain, neck pain, or reluctance to move - may suggest spinal involvement
  • Seizures, circling, behavior changes, or severe weakness - emergency signs that can occur with brain involvement

Mild valley fever can look like a lingering respiratory infection, while disseminated disease can look like an orthopedic, skin, or eye problem. See your vet promptly if your dog has a cough lasting more than a few days in an endemic area, or if a limp does not fit a clear injury. See your vet immediately for eye pain, sudden vision changes, seizures, severe breathing trouble, collapse, or intense bone pain. Travel history matters, so tell your vet if your dog has visited Arizona, California's Central Valley, New Mexico, west Texas, southern Nevada, southern Utah, or other dusty desert regions.

What Causes Valley Fever?

Valley fever is caused by inhaling fungal spores from the environment. The fungus lives in arid and semi-arid soil. When the ground is disturbed, microscopic spores can become airborne and enter the lungs. Dogs are at particular risk because they spend time close to the ground, sniff soil, and may dig in dusty areas.

The disease is most strongly associated with Arizona and California, but it also occurs in New Mexico, Nevada, Utah, west Texas, northwestern Mexico, and parts of Central and South America. Cases have also been reported outside traditional endemic areas, including Washington state. Regional risk can shift over time with weather patterns, land use, and climate conditions.

Risk is highest for dogs that live in or travel through endemic areas. Outdoor activity, digging, hiking, construction exposure, and dust storms can all increase exposure. Young, active dogs may be overrepresented in some case series, and any dog with a weakened immune response may have a harder time controlling infection.

Valley fever is not caused by food, water bowls, or contact with another infected pet. It is an environmental disease. That means prevention focuses on reducing dust exposure where possible, not isolation from other dogs.

How Is Valley Fever Diagnosed?

Diagnosis usually starts with history and pattern recognition. If your dog has lived in or traveled to an endemic area and has a chronic cough, fever, weight loss, unexplained lameness, or eye inflammation, your vet may recommend valley fever testing early in the workup.

The most common test is serology, often called a valley fever titer. This blood test looks for antibodies against Coccidioides. A positive result in a dog with compatible signs strongly supports the diagnosis. However, early infection can test negative, so your vet may repeat the test in a few weeks if suspicion remains high.

Chest X-rays are commonly used to look for lung changes and enlarged chest lymph nodes. If your dog is limping, your vet may recommend bone or joint imaging because valley fever can cause destructive bone lesions. Blood work is also important before and during treatment to assess overall health and monitor for medication effects.

In some dogs, your vet may recommend sampling a swollen lymph node, skin lesion, or other abnormal tissue. Finding the organism's characteristic spherules on cytology or biopsy can provide a more definitive diagnosis. Advanced cases, especially those with neurologic signs, may need MRI and spinal fluid testing through a specialty hospital.

Treatment Options for Valley Fever

Spectrum of Care means you have options. Here are treatment tiers at different price points.

Conservative: Uncomplicated Pulmonary Valley Fever

$350–$900
Best for: Dogs with suspected or confirmed primary lung disease that are stable, eating, breathing comfortably, and can be managed as outpatients with close follow-up.
  • Office exam and review of travel or regional exposure
  • Valley fever titer blood test
  • Baseline CBC and chemistry panel before antifungal therapy
  • Chest X-rays if respiratory signs are present
  • Generic fluconazole as the usual first medication when your vet feels it fits the case
  • Symptom support such as appetite support, cough relief, or pain control if needed
  • Recheck exam and repeat blood work or titer monitoring every 2-4 months
Expected outcome: Often good when disease is limited to the lungs and treatment is started early. Many dogs improve clinically within 1-2 weeks, but medication commonly continues for 6-12 months or longer.
Consider: Lower upfront cost range, but it still requires months of medication and monitoring. A dog may relapse if medication is stopped too early, and some dogs later prove to have more widespread disease than first expected.
Most Common

Standard: Disseminated Valley Fever Management

$900–$3,000
Best for: Dogs with spread beyond the lungs, including bone, joint, skin, lymph node, or eye involvement, but who are still candidates for medical management.
  • Expanded diagnostics such as chest and limb X-rays, repeat titers, and full lab monitoring
  • Fluconazole or itraconazole selected by your vet based on disease location, tolerance, and response
  • Pain management for bone or joint involvement
  • Targeted eye medications if ocular inflammation is present, often with ophthalmology input
  • Longer treatment course, commonly 12-18 months and sometimes longer
  • Serial rechecks with blood work, titer monitoring, and repeat imaging when bone lesions or lung disease need tracking
  • Hospital care if dehydration, poor appetite, or breathing difficulty develops
Expected outcome: Fair to good in many dogs with consistent treatment and monitoring. Bone disease can take months to improve, and some dogs need long-term or lifelong medication to control relapse.
Consider: Higher total cost range because treatment lasts longer and follow-up is more involved. Medication side effects and relapse risk are more common than in straightforward lung-only cases.

Advanced: CNS, Refractory, or Critical Cases

$3,000–$9,000
Best for: Dogs with seizures, severe neurologic signs, vision-threatening eye disease, severe disseminated infection, or poor response to first-line treatment.
  • Referral to internal medicine, neurology, or ophthalmology
  • MRI or other advanced imaging when brain or spinal cord disease is suspected
  • CSF testing or tissue sampling when appropriate
  • Higher-intensity antifungal planning, often centered on fluconazole for CNS penetration
  • Consideration of amphotericin B, posaconazole, voriconazole, or combination therapy in selected refractory cases
  • Hospitalization for oxygen, IV fluids, nutritional support, or seizure control when needed
  • Long-term or lifelong monitoring with repeated exams, lab work, and medication adjustments
Expected outcome: Guarded, especially with brain or spinal cord involvement. Some dogs can still achieve meaningful long-term control and good daily function, but treatment is intensive and relapse remains a concern.
Consider: Highest cost range and most complex care plan. Advanced antifungals and specialty imaging can add substantial expense, and some dogs need lifelong medication even after improvement.

Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.

Questions to Ask Your Vet About Valley Fever

Bring these questions to your vet appointment to get the most out of your visit.

  1. Based on my dog's signs and travel history, how likely is valley fever compared with pneumonia, cancer, or another fungal disease?
  2. Do you recommend a valley fever titer now, and if it is negative, when should we repeat it?
  3. Does my dog need chest X-rays, bone imaging, or referral testing to look for spread beyond the lungs?
  4. Why are you recommending fluconazole versus itraconazole or another antifungal in my dog's case?
  5. What side effects should I watch for at home, especially appetite changes, vomiting, diarrhea, coat changes, or increased drinking and urination?
  6. How often should we recheck blood work and titers while my dog is on treatment?
  7. What signs would make you worry about eye involvement, bone spread, or brain involvement?
  8. What is the expected cost range over the next 6-12 months, including medication and monitoring?

Preventing Valley Fever

There is no widely available commercial vaccine for dogs at this time. Prevention focuses on lowering exposure, especially for dogs living in high-risk parts of the Southwest. That means reducing digging, avoiding dusty lots and construction zones, and keeping your dog indoors during dust storms or very windy conditions when possible.

Yard design can help a little. Ground cover, gravel, or other landscaping that reduces bare dust may lower exposure around the home. Still, complete prevention is difficult because spores are part of the natural environment in endemic regions.

Early recognition matters as much as prevention. If your dog develops a cough that lingers, unexplained fever, weight loss, or a limp without a clear injury, bring up valley fever with your vet. This is especially important if you live in Arizona or your dog has traveled through desert areas.

If your dog has already had valley fever, follow your vet's recheck plan closely. Stopping medication too early is a common reason for relapse. Some dogs recover fully after a finite course, while others need much longer management. The right plan depends on where the infection is, how your dog responds, and what monitoring shows over time.

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