Conservation officers on Vancouver Island are telling residents to watch out for cougars after a big cat took off with a woman’s dog on a popular trail.

Nanaimo resident Serra Stewart was walking with her Chihuahua Charlie last week when it was snatched by a young cougar on Mount Benson. The tiny dog was not on a leash.

“She screamed maybe five or 10 seconds and then it was done,” Stewart says of the terrifying ordeal.

She ran after the cougar, but couldn’t get very close – and her beloved dog was gone.

“I threw my backpack off and chased [the cougar], which in hindsight was probably not the smartest thing to do,” she said.

Stewart, who carries bear spray and bells, said there wasn’t enough time to react when the cat approached.

The encounter does not come as a surprise to conservation officers, who say sightings have increased this year because of a population boom. Vancouver Island has the largest population of cougars per capita in North America.

Last month there were three separate reports of aggressive cats just outside Cumberland, where a motorcyclist said a cougar tried to attack him.

The population spike in B.C. and resulting conflicts mean a jump in the number of euthanized cougars as well: 117 were put down between March 2013 and March of this year -- a 50 per cent increase over the previous year.

One aggressive cat was euthanized on the Galloping Goose Trail in Victoria in June after it showed signs of aggression and approached people using the park.

The latest incident has prompted a warning for Nanaimo's Mount Benson area in particular.

Conservation Officer Tony Sterling urges dog owners to stay close together and keep their dogs on-leash.

“If they're not on leash, have good control over the dogs because they're either going to irritate the predators or act as an attractant and bring the predator back to the people," he told CTV News.

With a report from CTV Vancouver’s Penny Daflos