Table of contents
Key Takeaways
- Valley Fever is a fungal infection dogs catch by inhaling spores from desert soil, and an estimated 6 to 10 percent of dogs in Maricopa and neighboring counties get sick with it each year.
- The most common early signs are a lingering cough, fever, low energy, and reduced appetite, and if the infection spreads it often settles in bone and causes limping, though it can also reach the skin, eyes, heart, or nervous system.
- Antifungal medication treats Valley Fever effectively, but the course usually runs six months to a year or longer, so early testing and finishing the full course both matter.
Valley Fever in dogs is common enough around Phoenix that it is worth understanding before your dog ever shows a symptom. It is a fungal infection that comes from our desert soil, and the two things owners tend to notice first are a cough that will not clear up or a limp with no obvious cause.
Those symptoms overlap with plenty of other conditions, which is part of why dogs here sometimes go undiagnosed longer than they should. Most dogs who get sick do recover with treatment, and treatment generally goes better when the infection is caught before it spreads.
Below is what our vets want Phoenix dog owners to know: what to watch for, how testing works, what treatment involves, and what you can do to reduce exposure.
What is Valley Fever, and how do dogs get it?
Valley Fever is an infection caused by Coccidioides, a fungus that lives in the soil across the southwestern deserts. Dogs get it by inhaling microscopic spores that become airborne when soil is disturbed, whether by digging, wind, dust storms, or construction. It is not contagious, so a dog cannot pass it to another pet or to a person, and it does not travel the other way either.
Other names you may hear. You may also see it called coccidioidomycosis, or hear it shortened to cocci or referred to as desert rheumatism. All of these describe the same infection.
How common it is here. This is very much a Phoenix problem. Arizona accounts for a large share of all cases, and estimates suggest that 6 to 10 percent of dogs in Maricopa, Pinal, and Pima counties get sick with Valley Fever in a given year. Dogs are exposed simply by living here and sniffing, digging, and breathing the desert air, and exposure rises during dry, dusty, windy stretches and after storms churn up the soil.
Not every exposed dog gets sick. Research from the University of Arizona suggests that around 70 percent of dogs fight off the fungus on their own and may build some immunity in the process, sometimes without ever showing a sign. The dogs who do get sick are often those exposed to a heavy dose of spores or those whose immune systems cannot keep the infection in check.
Why the timing is hard to trace. Symptoms can appear weeks, months, or in some cases years after the exposure that caused them. Because of that, there is often no recent event an owner can point to when the illness finally shows up.
Which dogs are most at risk?
Any dog living in or visiting the desert can be exposed, but a few groups face higher risk. Dogs who dig and spend a lot of time outdoors in dirt stir up and inhale more spores, so enthusiastic diggers and dogs with big, dusty yards see more exposure than dogs who spend most of their time indoors or on paved surfaces.
Dogs new to Arizona. This includes the pets of snowbirds and new residents. They have had no chance to build the natural immunity a longtime desert dog may have developed, so their first year or two here carries more risk.
Age and immune health. Very young dogs, seniors, and dogs with weakened immune systems tend to have a harder time controlling the infection once it takes hold.
Season. Risk can climb after the monsoon, since summer rains help the fungus grow and the spores then disperse as the soil dries out.
What are the symptoms of Valley Fever in dogs?
Symptoms fall into two patterns, depending on whether the infection stays in the lungs or spreads through the body. The early signs are vague and easy to mistake for other illnesses. Because of that, a cough or a limp that lingers in a Phoenix dog is worth having looked at rather than waiting out.
When it stays in the lungs. Most cases begin here, since the lungs are where the spores land first. This is called the primary or pulmonary form, and the common signs are:
- A persistent cough, which may be dry and harsh or moist
- Fever
- Lethargy and low energy
- Reduced appetite
- Weight loss
These can look a great deal like kennel cough or another respiratory bug at first, which is part of why Valley Fever gets missed early. A cough that does not clear up the way a routine illness would is a reason to have your dog checked.
When it spreads beyond the lungs. If the infection is not controlled, it can travel through the body, which is called the disseminated form. The fungus has a particular affinity for bone, so lameness is one of the most recognizable signs:
- Limping or lameness, often shifting or recurring, with pain or visible swelling over a bone or joint
- Non-healing skin sores, draining wounds, or abscesses
- Eye changes such as redness, cloudiness, or signs of vision trouble
- Neurologic signs, most commonly seizures, along with wobbliness, behavior changes, or neck and back pain
- Signs of heart involvement, such as fluid buildup, weakness, or a swollen belly
Disseminated disease is more serious and harder to treat than a lung-only infection, and it usually requires longer and more intensive care. That is the main reason the early, lung-stage symptoms are worth acting on.
How is Valley Fever diagnosed?
Diagnosis combines your dog's symptoms with a specific blood test and imaging. The key test is a blood titer, an antibody test that looks for the body's immune response to the fungus, and it is usually paired with chest or limb X-rays to look for changes in the lungs or bones. Some cases need additional bloodwork, a sample from a lesion, or further imaging to complete the picture.
Because the symptoms overlap with so many other conditions, a vet's familiarity with the disease matters. One advantage of living in an endemic area is that Phoenix-area veterinarians see Valley Fever regularly and know when to test for it.
What to mention at the visit. If your dog has a cough, a limp, or other signs that fit, tell us about any recent digging or dust exposure. That context helps your vet decide how strongly to suspect Valley Fever and how quickly to test.
Is Valley Fever treatable, and is it curable in dogs?
Yes. Valley Fever is treatable, and most dogs recover with appropriate care, especially when the infection is limited to the lungs. The mainstay of treatment is antifungal medication, most commonly fluconazole, with itraconazole or, in severe cases, amphotericin B as alternatives. Alongside the medication, your dog may need supportive care such as pain relief or cough treatment.
How long treatment lasts. The length surprises most owners. Antifungal therapy typically runs many months, often six months to a year or more, and some dogs with severe or disseminated disease need medication for life. Your vet will monitor progress over time, usually with repeat titer tests, and adjust the plan from there.
Why finishing the full course matters. Many dogs start to feel better within a few weeks of starting medication, and it is tempting to ease off once the cough fades and energy returns. Stopping early is one of the most common reasons the infection returns, and relapses can be more difficult to treat than the original illness. The decision to stop medication should come from your vet, guided by repeat titer tests and your dog's overall progress, rather than from how your dog looks day to day.
What the outlook depends on. Recovery depends largely on how far the infection spread. Dogs with lung-only infections generally do well. Disseminated cases, particularly those involving the brain or heart, carry a more guarded prognosis and a higher chance of relapse.
Because treatment runs so long, it helps to have support between rechecks. Modern Animal members can reach our care team anytime through 24/7 Virtual Care with questions that come up mid-course, and you can keep your dog's medications and visit history in the Modern Animal app so nothing gets lost over a year of treatment.
Can you prevent Valley Fever, and is there a vaccine?
Prevention is difficult because the fungus is so widespread in our soil, but you can lower your dog's exposure. There is no widely available vaccine yet.
Where the vaccine stands. A canine Valley Fever vaccine developed at the University of Arizona has shown strong protection in studies and has been working through the approval process toward commercial availability. Timelines have shifted more than once, so ask us for the current status rather than assuming it is on the shelf.
What reduces exposure in the meantime. A few habits help:
- Discourage digging, especially in loose dirt and rodent burrows
- Avoid dusty areas and freshly disturbed or excavated soil
- Bring your dog indoors during dust storms
- Keep bare-dirt areas in your yard to a minimum to cut down on airborne dust
None of this eliminates the risk that comes with living in the desert. That is why knowing the symptoms and acting on them promptly remains the most useful thing an owner can do.
What does it cost to test and treat Valley Fever?
The cost of diagnosing and treating Valley Fever varies by location and, most of all, by how serious the case is. A lung-only infection caught early is very different from a disseminated case that requires extensive imaging, longer medication, and ongoing monitoring.
Several factors shape the final price: whether the visit is routine or urgent, your dog's age and health history, whether the infection is limited to the lungs or has spread, the length of the antifungal course, and how much monitoring is needed along the way. Because treatment often spans many months, it helps to understand the plan up front so you can budget for the full course rather than visit by visit.
For a full breakdown of service and test pricing at Modern Animal, visit modernanimal.com/pricing. Everything is listed transparently so you know what to expect before you come in.
The bottom line. Valley Fever in dogs is a normal part of desert life here. The fungus is in our soil, exposure is hard to avoid entirely, and most dogs who get sick recover well when the disease is caught and treated. Recognizing the signs is what makes the biggest difference, since a cough that lingers, a fever, fading energy and appetite, or an unexplained limp in a Phoenix dog all warrant a closer look.
If your dog is showing any of these symptoms, it is better to have them checked than to wait and see whether they pass. You can book a visit at a Modern Animal clinic so we can test and start treatment if needed, or message our team if you are not sure whether what you are seeing needs an appointment.
Frequently Asked Questions
The most common early symptoms come from a lung infection and include a persistent cough, fever, lethargy, reduced appetite, and weight loss. If the infection spreads beyond the lungs, it often affects the bones and causes limping or lameness, and it can also cause non-healing skin sores, eye changes, seizures or other neurologic signs, and signs of heart involvement. Our vets recommend having any cough or limp that lingers in a Phoenix dog evaluated rather than waiting it out.
Dogs get Valley Fever by inhaling microscopic fungal spores that live in desert soil and become airborne when the ground is disturbed by digging, wind, dust storms, or construction. It is not contagious, so dogs cannot catch it from another animal or from a person. Around 70 percent of dogs that inhale the spores fight off the fungus without ever getting sick. Those who do develop the illness may show symptoms weeks, months, or even years after the exposure.
Not one that is widely available yet. A canine vaccine developed at the University of Arizona has shown strong protection in research and has been moving through the approval process toward commercial release, though availability timelines have changed more than once. Until it reaches the market, the best protection is reducing exposure and recognizing symptoms early. Ask us for the latest on the vaccine at your dog's next visit rather than relying on older news coverage.
Most dogs recover with proper treatment, particularly when the infection is limited to the lungs. Treatment relies on antifungal medication and usually lasts many months, often six months to a year or longer, and some dogs with severe or widespread disease need medication for life. Lung-only cases generally have a good outlook. Cases that have spread, especially to the brain or heart, are more serious and carry a higher chance of relapse, so early diagnosis makes a meaningful difference.
You cannot eliminate the risk that comes with living in the desert, but you can reduce it. Discourage digging, especially in loose soil and rodent burrows, avoid dusty and freshly disturbed areas, bring your dog inside during dust storms, and minimize bare-dirt areas in your yard. Learning the symptoms matters just as much, because the dogs who do best are the ones whose owners recognize the signs early and get them tested quickly.
Antifungal medication works slowly against Coccidioides, and the fungus can persist in the body well after a dog looks and acts healthy. Our vets typically continue treatment for six months to a year or more and use repeat titer tests to track whether the infection is actually resolving. Dogs often feel better within weeks, but stopping at that point is one of the most common causes of relapse, so the medication should continue until your vet says otherwise.