Scientists Tackle Catalina Island Fox Tumor Mystery

posted: 12/08/15
by: Discovery.com Staff
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Veterinarians are one step closer to solving the mystery behind the unusually high occurrence of ear tumors that plagues a federally protected fox population on Catalina Island.

In recent years, scientists noted that half of the island's foxes had developed ear tumors, approximately two-thirds of which were malignant. Nearly every fox on the island was also found to be infected with ear mites.

In 2009, a research team from the University of California at Davis, the Institute for Wildlife Studies and the Catalina Island Conservancy began treating the foxes with acaracide, a chemical agent that has proven effective in treating ear mites in domestic dogs and cats.

Catalina Island foxes
Julie Lynn King/Catalina Island

After a six-month trial period, the prevalence of ear mites dropped 88%. The presence of tumors also has dropped significantly, researchers say.

Related: 13-Foot Giant Oarfish Washes Up on Catalina Island

"It's rare to have a success story," UC-Davis student Megan Moriarty, the lead author of a new study about the mite treatment, says in a news release. "It was interesting to see such striking results over a relatively short time period."

Researchers still haven't pinned down exactly why so many of the island's foxes developed tumors, although they believe that genetics play an important role. While other island fox populations are commonly infected with ear mites, their cancer rates are far lower than the Catalina Island population.

"Catalina foxes have an over-exuberant tissue reaction to the same stimuli -- the mites -- and that appears to lead to the tumors," UC-Davis veterinarian Winston Vickers explains. "That's why we gravitate toward genetics in addition to other factors."

Vickers' and Moriarty's newly published research is detailed in two studies in the journal PLOS ONE.


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