Colorado wildlife officers had to euthanize a sick bear after receiving multiple calls from concerned residents in Telluride.

And during a necropsy, wildlife officers came across a disturbing discovery inside the bear.

"There was all these paper towels, wipes, plastic bag type materials, and indigestible food content," said John Livingston, Colorado Parks and Wildlife spokesperson. "Trash content ... wasn't able to move its way through to the lower intestines."

All of which was prohibiting the male black bear from absorbing proper nutrients.

"A bear like this is about 400 pounds and has a lot of fat on it," Livingston told CNN, which means the mammal would have possibly starved for months before dying.

"To be eating and eating and not able to break down any of that food would have been a really sad and horrific way for that bear to suffer as it died," he said.

Officers had to make an 'unfavorable call'

"The first thing we noticed right away was a little bit of foam around its mouth," Livingston said.

While the foaming didn't appear to be rabies, officers noticed other concerning behaviors. The bear also had puffy eyes, which "indicated that it was battling some kind of infection," Livingston noted.

"He would walk about 20 or 30 yards at a time before needing to lay down."

These symptoms signaled to the wildlife officers the bear was in a lot of abdominal pain, the spokesperson said.

"We could not leave a sick bear like this knowing it was suffering and struggling to survive," said Rachel Sralla, Colorado Parks and Wildlife area manager, in a news release.

"That's a horrific way to die, decaying from the inside out for that long. As officers, we had to make an unfavorable call," Sralla said. "It's a call we wish we never had to make." The bear was put down on the evening of September 9.

In addition to preventing the bear from suffering, "CPW made the decision to euthanize the animal for human health and safety reasons," the release said.

Although the decision didn't come easy, it brought a sense of relief to the bear country community.

"When you do a full analysis of what was happening inside that bear, our officers feel good about the decision," Livingston said. "We didn't let this bear suffer out there," he continued.

The euthanized bear was well-known in the Telluride area, and had been hazed away from public spaces by wildlife enforcement before. The same bear was suspected to be involved in a home entry earlier this summer, according to the press release.

'Bears can smell things up to five miles away'

However, if bears are frequently being seen in proximity to homes, it is cause for concern.

"If the bears are around your residential area all the time, somebody doesn't know what to do," Livingston said. "Because if that bear is not getting a food reward, it will move on and go back up into the mountains," he continued.

"It only takes one person that's, you know, leaving unsecure food to attract them out."

Bears are smart animals with a good sense of memory, allowing them to remember where they found and referencing it as a place to return to, according to the wildlife spokesperson.

"Bears have an incredible sense of smell, and can smell things up to five miles away," Livingston told CNN. "If it smells a trash food source that's left out, there's a good chance that, in our Colorado mountain towns, there's a bear within five miles that can smell that."

Colorado Parks and Wildlife officials issued a statement providing ways for residents and hikers to "bearproof" their homes and lives, warning "only people (like you) can prevent problems with bears."

"There's been a large push over the last decade to get more residents in mountain communities to buy bearproof trash cans," the wildlife spokesman said.

Livingston also suggests placing garbage cans out on trash day, instead of letting it sit, not keeping doors and windows open overnight, and not putting bird feeders in trees.

"It really takes everybody doing their part, whether they're a visitor to Colorado, or us who live here full time. It takes everybody to do their part to secure that trash so bears aren't getting into it."