Plague killed two cougars, a mother and her kitten, found in the Gros Ventres in mid-October, University of Wyoming researchers confirmed Wednesday.

Another cougar died of plague in the greater Yellowstone area earlier this year, and a fourth cougar, which was part of a Wildlife Conservation Society study, died last year.

Researchers from Beringia South found the dead mother and kitten after picking up a mortality signal on the mother’s radio collar. The adult cougar had been collared as part of a scientific study.

The mother was previously healthy and on or about June 1, she gave birth to a litter of three female kittens. Researchers found one kitten dead underneath the mother and one kitten was missing.

A third kitten was also wearing a radio collar, allowing researchers to recover her. Officials sent the surviving kitten to the Wildlife Research Center in Sybille for evaluation, and it will eventually become part of the cougar exhibit
at the Lincoln Park Zoo in Chicago.

Cynthia Tate, an assistant veterinarian with the Wyoming Game and Fish Department, performed the necropsy on the animals Oct. 26.

“She [the mother] was in excellent condition. She had a lot of body fat,” Tate said. “She had died acutely. There weren’t any signs of trauma, and you starting thinking of something toxic or some kind of disease.”

“When I necropsied the kitten, she had enlarged lymph nodes,” Tate said. “That's a very strong suggestive sign of plague in cats.”

Tate then sent samples to Ken Mills, a professor in the Department of Veterinary Sciences at the University of Wyoming, who diagnosed the disease.

Mills said three confirmed cases of the plague in the greater Yellowstone area, plus one case last year, could mean the disease is cycling through the rodent, flea and cat populations in the region.

While Mills said he didn't think the disease posed much of a threat to the overall cougar population, the bacteria can infect domestic cats and humans. Cats can contract the disease by either eating a rodent infected with the plague or by getting bit by a flea that carries the bacteria. Humans stand the most danger if the bacteria is inhaled into the lungs, causing pneumonic plague.

While the disease has caused five human deaths in Wyoming since 1978, Tate said the plague is not a cause for panic.

“It’s an interesting finding and something we want to pursue,” she said. “It's not surprising and there's certainly no reason to be overly concerned. This disease has been around a very long time.”

Mills said there are a number of antibiotics that work well in combating the disease.

People with domestic cats should watch for swollen lymph nodes and coughing, Mills said.

“If a cat has swollen lymph nodes and is coughing, get it to a vet,” he said.

Tate said hunters should wear gloves when skinning animals and take care not to slice through the lymph nodes. The disease can kill rapidly, and hunters who experience flu-like symptoms two to six days after exposure to a cougar should call a doctor.