Signs of Valley Fever in Dogs As Fungal Disease on the Rise in U.S.

Valley fever, an infection caused by a type of fungus that lives nestled in dust and soil, has been reported more and more in U.S. residents over the past several years—but it's not just humans that can catch the disease.

The fungus behind the disease is known as Coccidioides, and it tends to grow in areas with low rainfall and high summer temperatures, such as the southwestern U.S.

The fungal spores become airborne when the soil is disturbed, such as by wind. People and animals can then inhale them.

Over 18,400 U.S. residents were reported to have fallen ill with Valley fever in 2019, according to Centers for Disease Control and Prevention (CDC) data, with many living in Arizona and California. This marked an increase of nearly 3,000 reports from the previous year.

In people, the disease can cause symptoms such as tiredness, a cough, fever, a rash, headaches and more. But it can also affect our pets.

Dogs are very susceptible to Valley fever. According to the University of Arizona's Valley Fever Center for Excellence (VFCE), dogs traveling through areas such as the central deserts of California, southwestern Texas or the low desert regions of Arizona and New Mexico are about as likely to contract the disease as their human owners.

When this happens, dogs may show symptoms including coughing, fever, weight loss, lack of appetite, and lack of energy. The animals may go on to develop pneumonia as the infection progresses.

When the fungus spreads beyond the lungs to other organs, the disease becomes known as disseminated Valley fever. This can cause symptoms such as: lameness; back or neck pain; seizures; and swollen lymph nodes under the chin, in front of the shoulder blades or behind the stifles.

In the disseminated disease, bones and joints are most commonly infected, with lameness the most common sign. Healthy adult dogs can usually ward off infections on their own and show only mild symptoms or none at all.

But dogs with weak immune systems or underlying health issues can develop serious illness and very young puppies and senior dogs are more susceptible.

According to VFCE, around six to ten percent of dogs living in the Pima, Pinal, and Maricopa counties of Arizona will get sick with Valley fever each year. Around 70 percent of dogs who inhale the fungal spores will not get unwell.

If a dog does get unwell, treatment with anti-fungal medications can be lengthy—six to 12 months in many cases—though it depends on the severity of infection. A central nervous system infection may need lifelong medication.

VFCE states there is no sure way to prevent a dog from getting Valley fever, apart from never traveling through places where the fungus grows. People can avoid activities that generate dust and discourage digging behavior or sniffing in rodent holes.

Other animals, such as cats, llamas, horses, zoo animals and non-human primates have also been reported with Valley fever.

Dog being petted
A stock photo shows a dog being petted. Dogs and other animals, as well as humans, can catch Valley fever, a fungal infection. Ksenia Raykova/Getty