VALLEY FEVER IN DOGS

By Cherese Cobb

In the desert soils of the Southwest, there’s a fungus called Coccidioides immitis (C. immitis) that causes Valley Fever (aka coccidioidomycosis). In the wake of summer rains, C. immitis releases tiny, infectious spores and whenever the soil is stirred up, the spores become airborne. If your dog inhales even just a few spores, he can become infected with Valley Fever— particularly if he has a weakened immune system. The results can be deadly.

Here’s what you need to know about the prevalence, symptoms, treatment, and prevention of Valley Fever.

Prevalence

According to Arizona University Health Sciences, 6–10 percent of dogs living in Maricopa, Pima, and Pinal counties contract Valley Fever each year. One in four dogs become sick with the disease by age two, outdoor dogs are 4.9 times more likely to be infected, and dogs that have more than an acre of land to roam are 6.2 times more likely to develop Valley Fever. According to a 2017 study from the University of CaliforniaDavis, the most affected breeds are Brittanys, Boxers, Bull Terriers, Dalmatians, English Pointers, Greyhounds, Vizslas and Weimaraners. Males are also more prone to the disease than females, but more research is needed.

Symptoms

There are two types of Valley Fever in dogs: primary and disseminated.

• Primary Valley Fever

According to a 2016 study in the Journal of Veterinary Internal Medicine, 80 percent of dogs that have Valley Fever get Primary Valley Fever. It’s limited to the lungs and causes a dry, hacking cough; swollen lymph nodes; fever; weight loss; and lack of appetite and energy. Symptoms usually start three weeks after infection, but C. immitis can stay in the body for up to three years before signs occur. However, 60 percent of dogs with primary Valley Fever are asymptomatic.

• Disseminated Valley Fever

When Valley Fever spreads outside of the lungs, it causes disseminated Valley Fever. At this stage, it invades the bones in the legs of dogs. Disseminated Valley Fever causes back or neck pain, non-healing skin wounds, eye inflammation, lameness or swelling of the limbs, and seizures. In rare cases, it can affect the eyes, testes, prostate, liver, spleen, gastrointestinal tract, or kidneys.

Diagnosis

A Cocci titer is used to check a dog’s blood for Valley Fever antibodies. Created by the immune system, antibodies are Y-shaped proteins that envelop Valley Fever and block it from entering healthy cells. If the Cocci titer is positive, the dog has been infected with the fungus. He may need x-rays (i.e., bone, chest, and joint), white blood cell counts, or biopsies with microscopic exams. If the Cocci titer is negative, it may need to be repeated in 3–4 weeks.

Treatment

Nine out of 10 dogs that are treated for Valley Fever will survive. They’re given antifungal pills twice a day for 6–12 months; however, dogs with disseminated Valley Fever may need antifungal medications for life. The most commonly prescribed medications are Fluconazole, Itraconazole and Ketoconazole. Ketoconazole is often prescribed with Vitamin C. It helps the medicine move through a dog’s bloodstream because it ups the acid in his stomach. It may also boost his immune system. Denamarin is a combination of a milk thistle extract and SAM-e. It’s used to help your dog’s liver cope with the “stress” of the Valley Fever drugs. While antifungal medications can cause a lack of appetite, nausea, vomiting, and diarrhea, dogs usually begin to feel better within one to two weeks.

Veterinarians may also prescribe appetite stimulants, cough suppressants, anti-inflammatories, pain medications, or antinausea drugs. Extra nutritional support may also be needed. For example, hand feeding one fresh, home-cooked or raw meal per day. If the fungus has invaded the bones, skin, or organs, 24-hour care, oxygen therapy and intravenous fluids, or medications may be required. According to a 2019 study in Medical Mycology, Valley Fever can also reactivate after treatment with immunosuppressive drugs.

Prevention

There’s no way to completely prevent Valley Fever in dogs. Avoid activities that generate dust and curb digging behavior with more quality playtime. Cover dirt in the yard with grass seed mats, deep gravel, or wood chips. Because C. immitis can live up to 12 inches deep in the ground, treating the soil isn’t practical.

Vaccine

The University of Arizona Health Sciences has partnered with the National Institute of Health and Anivive Lifesciences in Long Beach, California, to create a Valley Fever vaccine for dogs. The vaccine is called delta-CPS1. It has a mutant strain of C. immitis that’s missing a large gene. During clinical trials with mice, it caused the Valley Fever fungus to die off in one to two weeks and lasted for at least six months. Preliminary data from a group of dogs vaccinated with the delta-CPS1 vaccine has not been released to date.

The possibility of a vaccine gives hope to many dog owners in the state of Arizona.