Six years ago, a nursing home opened its doors to a stray Chocolate lab named Rusty who was about to be put down at a nearby shelter. But little could anyone have guessed that by saving the dog's life, he then would go on to bring so much joy to theirs.

Sue VanDeRostyne, who runs the Toulon Rehabilitation and Health Care Center in Illinois, first met Rusty after her sister found him wandering unattended in her backyard in 2008. The dog, thought to be around 2 years old, was wearing a collar with an out-of-state rabies tag, but it contained no information about who he belonged to.

"He was obviously someone's pet," says Sue. "We went everywhere trying to find the owner."

Eventually, they decided to drop Rusty off at the local animal shelter in hopes that someone might come claim him there. But after a week without any luck, Sue got word that Rusty's time was up.

"She called me on the seventh day, which was the day they would mostly likely be putting him down, saying nobody had claimed him," Sue says. "I actually left work, put blankets and sheets from the nursing home and went and picked him up in my car. And he's been here ever since."

Back at the nursing home, which specializes in caring for seniors with Alzheimer's and dementia, the lost dog was given a place to live alongside its nearly 100 live-in residents as Sue continued to try to track down Rusty's owner, but to no avail. It became clear, however, that Sue's gesture of kindness not only gave the friendly dog a new home -- it gave him a purpose as well.

Rusty soon established himself as the nursing home's resident pet, bringing happiness and comfort to seniors who needed it the most.

"He has made a huge difference. Oftentimes, they don't get visitors. But with Rusty though, if he walks by them and someone holds out their hand, he will stop and go closer to them to get petted," says Sue.

"He has many different names because the residents say, "Hey Brownie" or "Hey Misty" -- probably whatever name their dog had. If somebody is sad and they're sitting quietly, sometimes he'll just go to them."

But the former stray's positive influence doesn't end there. Despite having no training, Rusty has shown a remarkable aptitude as a therapy animal, just by being himself.

"We had a resident who wouldn't participate in therapy and he loved Rusty. We took Rusty into therapy and he had some toys, so the resident would throw the toys and Rusty would bring them back. The resident was getting arm exercises and he didn't even know it," say Sue.

"After about a week of doing that the resident then actually stood without even thinking about it, with some help of the therapist, but that was such a neat thing. It was a dog that got him to do things."

Naturally, being a nursing home's resident pet isn't without its perks.

"We had a resident who would send people to the store to buy treats for him. He knew right where her room was," she says. "Another lady insisted that she get a cheese sandwich every night. We discovered that it was because half was for her and the other half was for him. And he knew right where her room was, too."