Valley fever in dogs and cats

If you are reading this because your dog has had a dry cough for a week, or because a titer test has just come back positive, here is the short version first. Most dogs who get sick from Valley fever recover with treatment. It is not contagious to your other pets, and it is not contagious to you. What follows is what to watch for, what happens at diagnosis, and what treatment actually looks like — sourced rather than guessed, for a condition that is dramatically more common here than almost anywhere else in the country.

How urgently to act

No page can diagnose your dog. But if you are trying to work out how quickly to move tonight, this is how to sort it.

Go to an emergency vet now for a seizure, a sudden collapse or extreme disorientation, laboured or rapid breathing at rest, pale or blue-tinged gums, sudden vision loss, or a limb so swollen and painful your dog will not bear weight on it at all — particularly alongside a fever. These are the signs associated with the more serious, spread-through-the-body form of the disease described below, and they warrant emergency evaluation rather than a wait-and-see approach.

Call your regular vet today, but it can wait until morning, for a cough that has lingered more than a few days — especially a dry, harsh one — new loss of appetite or a drop in energy, mild soreness or limping in one leg without collapse, or unexplained weight loss.

Book a regular appointment if your dog has already tested positive and is on treatment and you have questions about the medication, the timeline or side effects; if you want a baseline conversation about your dog’s risk given how common this is in this specific county; or if there are no symptoms at all and you are wondering whether testing makes sense.

Why this matters more here than almost anywhere else

Valley fever — coccidioidomycosis — is not a generic “Southwest” risk. It is concentrated here to a degree most owners do not realise. A peer-reviewed study analysing nearly 900,000 canine serologic tests from US diagnostic labs between 2012 and 2022 found overall canine seropositivity of 37.6%, with a mean annual Arizona incidence of 86.8 cases per 10,000 households (Journal of Infectious Diseases, 2025). Broken down by county, the same study put Maricopa County at 94.4 cases per 10,000 households per year, with neighbouring Pinal County at 69.0 — and Pima County, at 157.9, the highest in the nation (same source). Arizona’s overall rate runs roughly 100 times that of California, Nevada or New Mexico (same source).

The disease is also spreading geographically: the share of US counties with seropositive dogs grew from 2.4% in 2012 to 12.4% in 2022 (same source). The same research found that monthly dog infection rates track monthly human infection rates fairly closely — a statistical correlation of r=0.65 in Arizona — which is part of why dogs are sometimes called a sentinel species for this disease, though the researchers note the correlation is not strong enough to forecast human outbreaks ahead of time (same source).

The University of Arizona’s Valley Fever Center for Excellence, a resource genuinely local to this area, estimates the disease costs Arizona dog owners at least $60 million a year collectively (VFCE, Valley Fever in Dogs).

It is commonly assumed that risk rises after monsoon storms disturb dusty soil. TKfind an authoritative source with hard seasonal case-count data for canine Valley fever in Arizona — the Valley Fever Center for Excellence and ADHS surveillance are the likeliest holders. No "high season" claim publishes here until one is confirmed.

How dogs and cats get it

Valley fever comes from inhaling fungal spores that live in the soil and become airborne when the soil is disturbed. Dogs are especially exposed because digging and ground-sniffing are simply what dogs do (VCA, Valley Fever in Dogs). In a susceptible dog, inhaling fewer than 10 spores can be enough to cause illness (VCA, Coccidioidomycosis in Dogs).

It is not contagious dog-to-dog, dog-to-cat or dog-to-human (VCA, Valley Fever in Dogs). A positive dog in the house is not a risk to your other pets, or to you.

What to watch for

Most dogs develop the milder, respiratory form of the disease. A smaller number progress to a more serious, disseminated form in which the infection spreads beyond the lungs.

Primary respiratory disease, the more common presentation, shows up as a harsh, dry cough, fever, loss of appetite, and lethargy or general depression, typically about three weeks after infection (VCA, Valley Fever in Dogs).

Disseminated disease brings lameness from bone or joint involvement, swollen and painful joints, persistent fever, weight loss, and eye inflammation that can lead to blindness (VCA, Valley Fever in Dogs). Neurologic involvement is rarer but serious — seizures are the most common neurologic sign when the disease reaches the central nervous system, alongside vestibular signs such as loss of balance, head pressing, back pain, and weakness or partial paralysis (VCA; dvm360, June 23, 2025). Cardiac involvement can cause right-sided heart failure with fluid build-up (dvm360, June 23, 2025).

In cats, Valley fever is less common than in dogs, but when it does occur the disease spreads beyond the lungs in roughly 60% of feline cases — a much higher share than in dogs, where most cases stay respiratory. In cats, the skin is the most common site the infection spreads to (dvm360, June 23, 2025).

How it is diagnosed

The primary test is antibody serology, most often an agar gel immunodiffusion (AGID) test that looks for two antibody types. IgM antibodies typically become detectable 2 to 5 weeks after infection; IgG antibodies take longer, becoming detectable at 8 to 12 weeks. AGID testing carries up to a 13% false-negative rate. A newer point-of-care lateral flow test is highly reliable when positive — 100% positive predictive value — but less reliable when negative, at 75% negative predictive value compared with AGID, which means a negative point-of-care result on its own does not rule the disease out (dvm360, June 23, 2025; VFCE).

One nuance matters more than most owners expect: there is no established correlation between how high a dog’s initial titer is and how severe the disease will turn out to be (dvm360, June 23, 2025). A high number on a test result does not predict a harder course of illness, and a low one does not guarantee an easy one. Chest radiographs and general bloodwork usually round out the diagnostic picture.

Treatment

Several antifungal drugs are used, and the choice depends on the individual case.

• Fluconazole is the most widely prescribed option in southern Arizona. It absorbs well from the gut, is generally better tolerated by the liver than the alternatives, and is preferred when the infection has reached the central nervous system or spine.
• Itraconazole is more potent and dosed once daily. It penetrates bone well, so it is often preferred for bone or joint disease, but it costs more and carries a higher risk of liver enzyme elevation.
• Ketoconazole is older and generally cheaper, but requires an acidic stomach environment to absorb properly, and it causes infertility in male dogs during treatment.
• Posaconazole and voriconazole are options for cases that do not respond to the first-line drugs.

Hepatotoxicity — liver-related side effects — occurs in up to 26% of patients on this class of drug, which is part of why monitoring bloodwork during treatment matters (dvm360, June 23, 2025; VFCE, Treatment).

One specific warning on compounded medication: a 2018 study found that 95% of compounded itraconazole samples tested were subtherapeutic, meaning the actual drug dose was too low to be reliably effective. Compounded formulations are specifically discouraged for this reason (dvm360, June 23, 2025).

How long it takes

On average, treatment runs 9 to 12 months, though the range spans anywhere from 6 months to several years. The general rule is to keep treating until titers fall to 1:2 or lower and any visible lesions resolve — and many clinicians continue for another 3 to 6 months past that first low or negative titer rather than stopping immediately. Bone infections and central nervous system cases often require long-term or lifelong medication. Titers are typically rechecked every 3 to 6 months during treatment to track progress (dvm360, June 23, 2025).

What it costs

TKthis is the highest-value single research task left on this page. Pull the actual figures from the 2022 cost study "The costs of the diagnosis and treatment of canine coccidioidomycosis in endemic regions, USA" (PMID 40845432). The paper was identified during drafting but its figures were never extracted, and no dollar figure publishes here until they are.

What can be said with a source is this: generic fluconazole prices spiked five- to tenfold in 2013 during a manufacturer shortage, creating real financial hardship for owners already managing a months-long course (VFCE, Treatment). Given that compounded formulations carry a documented efficacy risk, cost pressure on this disease is a conversation to have directly with your vet about brand options and pharmacy pricing — not a reason to substitute a cheaper, unverified formulation on your own.

Prognosis

Overall recovery rates with treatment range from 60% to 90%, with worse outcomes tied to central nervous system involvement or infection in multiple bones (VCA, Coccidioidomycosis in Dogs). The takeaway most owners want to hear is a real one: most treated dogs get better.

TKfind a source addressing whether a dog that has recovered from Valley fever can be reinfected later. Nothing in the drafting research addressed this directly, and it is a question owners ask constantly.

Prevention, and the vaccine

There is currently no reliable way to prevent Valley fever beyond limiting exposure to disturbed, dusty soil. No source reviewed for this page described an effective prevention method beyond that, and it is stated plainly here rather than implying there are more options than there are (dvm360, June 23, 2025).

A canine vaccine does not yet exist commercially. One is in development by Anivive Lifesciences, using a modified, avirulent strain of the fungus that causes the disease. As of the most recent sourcing available, it is not FDA or USDA approved and not available for purchase — the company has begun the formal USDA registration process but has not received approval (Anivive, Valley Fever; dvm360, June 23, 2025).

The research behind it is genuinely promising. A study published in the journal Vaccine, covered by the University of Arizona’s health sciences division, found that a two-dose regimen — an initial dose plus a booster 28 days later — prevented or greatly reduced disease in vaccinated research dogs after deliberate exposure, with roughly 90% of vaccinated dogs showing only minimal signs. A single dose without the booster did not provide adequate protection, and how long protection lasts beyond the study period has not been established (UA Health Sciences, Oct. 26, 2021; dvm360, June 23, 2025).

TKre-verify Anivive's approval status against current FDA and USDA records immediately before this page publishes — not at a later review date. This section was last checked against sources published through mid-2025, and approval status is exactly the kind of fact that moves without notice.