Just when Christine Petras had given up hope her family would be reunited with their missing border collie, she received the call she had been waiting for the past 9 months: Yo-Yo had been found.

“We thought maybe somebody found him and he’s a nice dog and they just decided to keep him,” Petras, 42, of Holbrook, said. “We certainly did not expect that phone call.”

Yo-Yo, who is four years old, was picked up Monday by the Brookhaven Animal Shelter after he was found in a wooded area near Sunrise Highway, about a mile from his home. His rescue delighted both his family and animal lovers online, who for months had shared Facebook posts and sightings in an effort to help find Yo-Yo.

Suffolk County police called shelter officials on Monday about a stray dog that had been reported, said shelter director Ashley Behrens. The black and white dog’s leg was caught in an animal trap, though the trap did not injure it, she said.

The dog was taken to Animal Emergency Services in Selden, where its microchip confirmed it was Yo-Yo.

The border collie had gone missing on May 9. Petras had met with a group of parents from her 6-year-old daughter’s school that day at Greenbelt Recreation Center so Yo-Yo and her children could play. Yo-Yo is skittish, however, and twisted away when another parent tried to pet him, Petras said.

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“The leash slipped out of my hand but I said ‘No big deal, he’s off-leash trained,’” she said.

But when well-meaning parentstried to help her regain control of Yo-Yo, he got spooked and ran off, Petras said. Friends and family members spent days, then weeks and then months searching for Yo-Yo and setting up feeding stations at all hours in Holbrook.

Pet owner communities across the Island rallied to help find him as the story spread online. Petras received dozens of messages with possible sightings, and some Facebook users even called local shelters and veterinarian offices.

One Facebook post Petras wrote about Yo-Yo was shared more than 3,640 times, and another from the animal shelter announcing his return was shared more than 1,200 times.

Behrens said it’s a unique case with a happy ending.

“It was obviously incredible that he was found and reunited with his family who never gave up hope,” she said.

Now Petras said Yo-Yo is back to sleeping in his favorite spot — her son’s room — and enjoying the company of his family. He lost nearly half his original weight and his paws are irritated, but he is otherwise healthy and on his way to recovery.

“Fatten him up and fix his feet and he’ll be good as new,” she said. “The kids are quite happy that he’s home.”