Outfoxing mange in the San Joaquin kit fox

The endangered San Joaquin kit fox is facing a new threat and the U.S. Fish and Wildlife’s Sacramento Field Office is joining others to help save the species. In addition to habitat loss, predation, and human induced mortality, the fox is facing a sarcoptic mange disease epidemic in Bakersfield, California, which was until recently a thriving population hub for the species.

Photo of a San Joaquin kit fox with mange

In Bakersfield, there have been over 90 known cases of mange in the
San Joaquin kit fox. This outbreak is particularly troubling because
Bakersfield hosts a stable population comprising about 10% of this
species’ population. - Photo Credit: CSU Stanislaus Endangered
Species Recovery Program

If you’re a pet owner, you’ve probably seen the word mange written on your pet’s monthly prevention medication or posted on the wall at your veterinarian’s office. Sarcoptic mange is a highly contagious and potentially fatal skin disease caused by parasitic mites. In foxes and other closely related species like coyotes and wolves, sarcoptic mange is caused by a canine-specific variety of mite that is not able to survive and reproduce on humans. Domestic dogs are easily protected from the disease, as long as they are receiving monthly tick and flea prevention medication.

After colonizing a mammalian host, these microscopic mites will burrow into the skin, depositing eggs, exoskeletons and fecal waste along the way; this leads to intense itching and hair loss, leaving the host more vulnerable to parasites and skin disease. If left untreated, sarcoptic mange can eventually result in death due to factors like secondary infection, hypothermia, dehydration and starvation. While mange has been widely documented in red fox populations across the globe, with the first recorded outbreak dating back to 1689, it has only just been documented in the San Joaquin kit fox within the last three years.

If left untreated, sarcoptic mange can eventually result in death due
to factors like secondary infection, hypothermia, dehydration and
starvation. - Photo Credit: CSU Stanislaus Endangered Species
Recovery Program

In 2013, the first cases of mange were reported in an urban population of kit fox inhabiting the City of Bakersfield. Since then, there have been over 90 known cases of mange in this population, with the number of infected individuals increasing each year. This outbreak is particularly troubling because Bakersfield hosts the last remaining stable population of San Joaquin kit fox.

Historically abundant throughout the San Joaquin Valley, kit fox now exist in small, fragmented populations. The overall population size of the San Joaquin kit fox is estimated to be as low as 3,000 individuals. While populations occurring in natural areas are subject to fluctuations in abundance due to availability of prey and water, urban kit foxes persist in an environment with a constant source of human-related food and water resources and fewer natural predators. Over the years, kit foxes in Bakersfield have maintained a population size of several hundred individuals and consistently high reproductive rates, but that stability may now be at risk.

Supported by funds from the Service, researchers at the UC Davis School of Veterinary Medicine, the CSU Stanislaus Endangered Species Recovery Program and the California Department of Fish and Wildlife are teaming up in an effort to stop this epidemic. Researchers plan to test the use of over-the-counter mange-preventive collars to reduce the occurrence of this disease. Kit foxes will be trapped at high risk sites in Bakersfield and, depending on severity, infected individuals will either be dosed with a topical parasiticide or taken to the California Living Museum for rehabilitation. Uninfected foxes will be divided into two groups: a treatment group and a control group. The treatment group will be fitted with mange-preventive collars and the control group will not be treated. Foxes in both groups will then be monitored for 9 months using radio tracking collars and remote cameras to detect differences in the occurrence of mange between the two groups.

Based on the results of this study, researchers can determine whether mange-preventive collars will be an effective tool for controlling this outbreak on a larger scale. The Service is committed to supporting our partners in this effort to gather information which may prove vital to the future persistence of this endangered species.

The Service is teaming up with our partners in an effort to stop this
mange epidemic. Researchers plan to test the use of over-the-counter
mange-preventive collars to reduce the incidence of this disease.
- Photo Credit: CSU Stanislaus Endangered Species Recovery
Program

After application of mange-preventive collars, foxes will be
monitored for 9 months using radio tracking collars and remote
cameras. - Photo Credit: CSU Stanislaus Endangered Species
Recovery Program

 

 


Story by Dana Herman, Sacramento Fish and Wildlife Office Biologist