A rescue dog has suffered the heartbreak of being adopted and then returned within 72 hours.

Jan Vega has been a volunteer at the Carson Animal Shelter in Gardena, California, for the past three years. "I started volunteering just for fun, excited to get dogs out of their kennels and give them some relief, but now it's become such a big part of my life and I'm so passionate about our animals," she told Newsweek. "All of our volunteers are."

It's a role that has seen her experience the highs and lows of animal rescue. Caramel's story touches on all of the above and, despite Vega's best efforts, might yet end on the lowest of lows.

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"Caramel has been at our shelter since August," Vega said. "He came as a stray. Unfortunately his family never came looking for him."

Someone eventually saw something in Caramel though and after two months at the shelter, it looked like he had found a forever home having been adopted by an animal lover from the local community.

"I thought that meant this person understood the due diligence that's required when taking a shelter dog home," Vega said. "I really thought we would never see Caramel again."

However, less than 72 hours after he said goodbye to the shelter and its staff, Caramel was returned. Vega was confused. "He's such a sweet dog, he's gentle, affectionate, and obedient," she said. "He would have made the best companion."

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That confusion turned to frustration when Vega learned Caramel had been returned "for being too puppy-like" and too much of a handful for his adopter.

"Caramel is just under two years old," Vega said. "He more than likely had a lot of pent up energy after being in a confined kennel 24/7, and was excited to be in a home!"

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Now Caramel is back in his enclosure in a development Vega describes as both "really sad and frustrating to see." Visiting him for the first time since he returned to the Carson Animal Shelter, Vega said it felt like Caramel had gone back to square one

"He was extremely scared and timid, tail tucked and all," she said. "The shelter is a really scary and loud place. I just worry this situation has confused him and left him in worse shape than when he first entered."

The worry is that things could get worse. In a study published in the Journal of Applied Animal Welfare Science, researchers sought to identify the shared characteristics of long-term shelter dogs.

They found that these dogs often demonstrated stress-related behaviors and had more difficulty relaxing in the shelter environment. Sadly, Caramel may not end up being a long-term shelter stay. Dogs can be euthanized at Carson Animal Shelter.

Vega has been posting to her TikTok, @_jannnnv, trying to drum up interest. Sadly, she's yet to have anyone come forward and express interest. "Unless we find an adopter or a rescue and foster that can help, Caramel won't make it out of the shelter," she said. "Caramel is good with other dogs, people are friendly, walks great on a leash, and knows commands. We're really hoping someone steps up and gives him a fair chance."

In the meantime, Vega hopes Caramel's experience helps those interested in adopting a dog remember the crucial "3-3-3" rule.

"First three days, give the dog space and alone time to acclimate to their new environment," she said. "Three weeks, gradually introduce the dog to other pets, family members, and new environments. Then at the three month mark the dog should have established trust and a bond with their owner."

Vega is still surprised at the number of dogs returned after a few days. "It doesn't happen overnight. It takes time," she said. "Caramel needed time."