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Winter 2013

Urban Jungle

The changing natural world at our doorsteps | Illustration and text by Patterson Clark      

March 5, 2013

Sarcoptic mange: Hounded by a mite

Alarmed when he saw a fox "running aimlessly and frantically" through his back yard in Takoma Park last month, Henry Allen alerted the police and posted his sighting on the neighborhood
e-mail discussion group, where others were reporting the same animal. Vigilance was high after news of a rabid fox attack on a woman in Rock Creek Park a week earlier.

The Takoma Park fox was distinctive in two ways: erratic behavior — which threw the rabies flag — and a ghastly skin disease, sarcoptic mange.

"I was appalled to see that it had no fur on its tail," said Allen, a former Post writer and editor, who described the tail as "completely denuded of its brush." In extreme cases, a fox with mange can lose all of its body hair.

"Every year we generally receive a couple reports of strange-looking wild animals that turn out to be foxes with mange," says Montgomery County Police Capt. Michael Wahl, director of the county's Animal Services Division. His officers have made several unsuccessful attempts at capturing the animals in humane live traps.

Jim Monsma, director of Second Chance Wildlife Center in Gaithersburg, reports getting a call about once a week regarding foxes with mange, "but our hands are tied by state regulations," he says. Because foxes are a rabies vector, the law requires that any adult fox brought to the center must be euthanized. The center can spare only healthy fox pups less than a year old — and even that requires special permits and precautionary vaccinations for the rehabilitators.

Without human intervention, foxes can recover from mange, but serious infections can prove fatal. The disease is caused by a highly infectious mite, which burrows just under the surface of the animal's skin. It feeds on lymph and lays eggs and waste as it gnashes and claws its microscopic tunnel. Low-level infections can cause hair loss and itching within a few weeks, but a bad infection, with as many as 32,000 mites per square inch, can yield a thick, relentlessly itchy crust that is vulnerable to secondary bacterial infection when the animal scratches or gnaws at the area.

More time spent scratching means less time hunting, which can lead to malnourishment and compromised immunity. If too much fur is lost, foxes can succumb to hypothermia.

One strain of the mite causes human scabies, but

Red fox with sarcoptic mange

the strain causing fox mange creates at most a temporary, itchy rash on people.

Dogs are highly vulnerable to fox mange, but for some dogs a prescription of ivermectin can cure them in a month. Because the drug can do the same for foxes, some fox advocates suggest medicating affected foxes with ivermectin-laced bait every two weeks. But delivering reliable doses in the wild can be tricky, and the bait might accidentally kill ivermectin-sensitive dogs, such as collies and Jack Russells.

The Fox Project, a conservation group based in Britain, says on its Web site that "spectacular recoveries [from sarcoptic mange] have been

achieved by use of two homoeopathic remedies," a combination of arsenicum and sulphur and a second dose of psorinum. However, "positive results are less convincing on foxes suffering more than 40 percent visible mange."

The National Fox Welfare Society, also in the U.K., suggests feeding foxes sunflower seed oil, fresh liver and vitamins A and D to help them recover from mange. The foxes that the NFWS nurses back to health in captivity are much more fortunate than Maryland's mangy tods and vixens: Britain is rabies-free.

Source: Wildlife Online