Valley Fever Treatment for Dogs and Cats in Scottsdale, AZ
Coccidioidomycosis, better known as Valley Fever, is a soil-borne fungal infection found throughout the desert Southwest. Led by Dr. Ale Aguirre, Diplomate of the American College of Veterinary Internal Medicine, the internal medicine team at Salt River Veterinary Specialists has extensive experience diagnosing and managing Valley Fever in dogs and cats, from first-time lung infections to severe, widespread disease.
What Every Pet Owner Should Know About Valley Fever
The fungus that causes Valley Fever requires high heat, low annual rainfall, and low altitudes, the conditions of the Lower Sonoran Life Zone, to survive. During summer, the fungus lives 6 to 8 inches below the surface. After periods of rain, it begins growing in the upper layers of soil and releases spores. Those spores are picked up by wind and dust storms and can be spread over great distances. Most patients develop the disease in the weeks to months following monsoon rains in the metro Phoenix area, but year-round infections can occur.
Most people and dogs living in areas where Valley Fever is prevalent will become infected at some point, and many infections resolve on their own without treatment. Only a small subset of animals and people ever become sick from the disease.
How Infection Occurs
Valley Fever is highly infectious but is generally not contagious from animals to people or from people to animals. After inhaling spores, most dogs begin coughing within one to three weeks. A small focal pneumonia develops first. If the immune system does not clear the infection, it can spread to the lymph nodes in the chest within about 10 days. Infection of the bones, eyes, heart, brain, spinal cord, and other organs can develop within one to four months.
Outdoor dogs, dogs that hike in the desert, and dogs that dig are more likely to become infected. Cats are affected less often, but even indoor cats can develop the disease. Breeds at higher risk include Labrador Retrievers, Golden Retrievers, Boxers, Dachshunds, and Siberian Huskies.
Signs of Valley Fever
Dogs often develop a dry, hacking cough first, usually accompanied by fever and decreased appetite. Weight loss is common, particularly with prolonged disease. When the fungus spreads beyond the lungs, signs depend on the organs involved:
- Limping or bone pain, sometimes with a bony swelling that drains pus
- Vision problems, behavior changes, or seizures when the eyes or brain are affected
- Weakness, lethargy, and a bloated belly when fluid accumulates around the heart
- Small raised skin lesions that can progress to large, weeping sores
Cats with Valley Fever tend to stop eating, hide, and develop fever and lethargy. Coughing may be noticed with activity. Skin lesions are more common in cats, while limping and bone lesions are rare.
Diagnosing Valley Fever
Diagnosis is based on clinical signs combined with one or more tests. Blood titer tests measure the body’s immune response to the Valley Fever organism; higher titers often indicate more severe or chronic infection. However, titers can be falsely negative in about 30% of dogs, especially very early in infection or in breeds such as Golden Retrievers, Boxers, and Dachshunds that mount a poor immune response. False positives can occur in pets that have previously recovered. Newer DNA-based tests that detect the organism directly can also help identify infection in some patients.
Imaging plays a key role. Thoracic radiography in coughing patients and x-rays of the legs in limping patients have a high probability of identifying active infection. A cardiac ultrasound may be recommended for weak patients with bloated bellies. Bronchoscopy can reveal enlarged lymph nodes, collapsed airways, and pus associated with Valley Fever pneumonia, and allows samples to be collected. Needle biopsies of affected tissues may also help confirm the diagnosis.
Treatment Options
Fluconazole is an oral antifungal medication that has been the mainstay of Valley Fever treatment in people and animals for many years. It works primarily by preventing the organism from reproducing, relying on the immune system to clear the infection. Fluconazole can reach the brain and spinal cord, making it valuable for neurological Valley Fever. Toxicity is uncommon, but vomiting, increased thirst, elevated liver values, and skin rashes can occur, so liver values are monitored periodically. Itraconazole and ketoconazole are related drugs used in patients that cannot tolerate fluconazole.
Amphotericin B is an IV medication used in patients that do not respond to oral therapy. It is typically given over several hours about three times weekly for several weeks. Amphotericin can kill the organism directly, but it can be toxic to the kidneys, so frequent blood and urine monitoring is required.
Newer-generation antifungals developed for people may be more effective in some cases but are significantly more expensive. Our team evaluates whether these medications are appropriate for patients with severe disease or poor response to fluconazole.
Supportive medications, including anti-inflammatories, steroids in select cases, and appetite stimulants, are often important, particularly for pets with fever or poor appetite. Pets with heart involvement may require additional procedures, and our surgical team treats complications such as pericardial disease, as described on our chest surgical conditions page.
Prognosis and Monitoring
Treatment usually continues for a minimum of six months and may last a year or longer. Some pets that cannot clear the organism require lifelong therapy. Recurrence is common when treatment is stopped too soon, so bloodwork and x-rays are repeated to guide the length of therapy. In general, treatment should continue for at least three months after test results return to normal. Reinfection is possible in limited circumstances.
Prevention
There is currently no commercially available Valley Fever vaccine for dogs or cats, so prevention focuses on limiting exposure:
- Walk dogs on city streets or in parks rather than in the open desert
- Keep windows closed and pets indoors on windy days, especially during dust storms
- Landscape bare-dirt yards with grass or rock to reduce dust
- Discourage digging, which significantly increases risk; strategically placed plants can help
Public Health Considerations
Valley Fever is generally not contagious from dog to dog or from dogs to people. People and pets in the same environment are both at risk from inhaling spores in the soil. There is a small risk of transmission from a draining or weeping skin lesion, so good hygiene should always be used when cleaning a wound thought to be caused by Valley Fever.
Learn more from our internal medicine department, visit our dedicated Valley Fever resource, or explore other conditions we treat, including tracheal collapse and chronic nasal disease. Ongoing antifungal medications can be ordered through our online pharmacy.
Valley Fever FAQs
Is Valley Fever contagious to people or other pets?
Valley Fever is generally not contagious between animals or from animals to people. Infection occurs by inhaling spores from the soil.
What are the first signs of Valley Fever in dogs?
A dry, hacking cough is often the first sign, usually accompanied by fever, decreased appetite, and lethargy.
Can a negative blood test rule out Valley Fever?
No. Titer tests can be falsely negative in about 30% of dogs, so imaging and other tests are often needed.
How long does Valley Fever treatment last?
Treatment usually lasts at least six months to a year, and some pets require lifelong therapy.
Can cats get Valley Fever?
Yes. Cats are affected less often than dogs and frequently develop skin lesions, poor appetite, and hiding behavior.
Is there a vaccine for Valley Fever?
There is currently no commercially available Valley Fever vaccine for dogs or cats.
How can I reduce my dog’s risk of Valley Fever?
Avoid walking in the open desert, keep pets indoors during dust storms, reduce bare dirt in your yard, and discourage digging.
Expert Valley Fever Care in the Valley
If your pet has a persistent cough, limping, or other signs of Valley Fever, our specialists can help. Call Salt River Veterinary Specialists at (480) 819-8630 or request an appointment online.