A senior shelter dog has taken to hanging back in the corner of the animal rescue he currently calls home, watching on as other dogs get adopted.

When Nico was found roaming the streets of Miami as a stray, he was in the worst shape imaginable.

The litany of health issues he was struggling with when he was initially brought to Miami Dade Animal Services makes for difficult reading. This poorly 19-pound terrier mix had an ear infection, an alarming mass on his body, was unneutered and his teeth were rotting away.

Thought to be around eight years of age, as a senior dog with such an extensive list of health issues, the stark reality was that, at that precise point, Nico was facing a very difficult future.

Thankfully, True and Faithful Rescue Mission, a rescue dedicated to saving seniors and unwanted dogs from high kill shelters, came to his aid. "The shelter got a hold of us and asked if we would save him," a spokesperson for the True and Faithful Rescue Mission in Venice, Florida, told Newsweek. "We are Miami Dade Animal Services top pulling rescue and we save all seniors that have huge medical needs."

They then set about making this brave dog "whole again." He was neutered, underwent dental treatment and received the meds necessary to address his ear infection.

Since then, he's come on leaps and bounds with blood tests returning perfect results and regular shots of the painkiller Librela helping address an uncomfortableness caused by some ongoing osteoarthritis.

At the True and Faithful Rescue Mission, Nico has a five-acre ranch to explore but, for the most part, likes to settle in quiet corners. "He must have been an outside dog and finds spots in a cool area to take naps," the shelter said.

Sadly, however, his desire to hide away might be hindering his chances of finding a forever home to see out his senior years in peace.

Research has highlighted how important first impressions can be in an animal shelter. In a 2014 study published in the journal Applied Animal Behavior Science, researchers observed 250 different interactions between potential adopters and shelter dogs.

They found that dogs ignoring play initiations by the adopter reduced the likelihood of adoption while lying in proximity to the adopter increased the likelihood of adoption.

Maybe it's down to past experience, or a nervousness with new people, but Nico is guilty of this kind of behavior. A video posted to TikTok by the True and Faithful Rescue Mission highlights how he likes to hide and watch from afar as other dogs play and take the limelight.

"Nico is one of those hidden gems who, despite his gentle soul and endless loyalty, often gets overlooked," a caption accompanying the heartbreaking footage reads. "Day after day, he watches other dogs find their forever homes while he waits patiently, always the quiet observer, hoping his turn will come."

Despite this, the shelter has not given up hope of someone taking a shine to this gentle senior pup. "Nico is shy and extremely sweet. We do not know his history but are determined to make his future brighter," they said. "Nico is older and needs anti-inflammatory medicine. More than that, he just needs a home that will give him time, love and patience."

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