It’s every dog owner’s worst nightmare: After a late night out, Carole and Verne King came back to their pet-friendly hotel in Montana to find their beloved 7-year-old border collie missing.

"We came back at 11:30, went to the room, walked in, and both of us were asking that question, 'where's Katie?'" Verne King told "Good Morning America."

A storm had spooked Katie and sent her running out of an unlatched hotel door.

The couple, originally from Washington, love to go on vacations to Montana and they often take Katie with them.

After searching for hours that night, they continued searching into the next week throughout the rugged terrain. A month passed -- still with no sign of the dog they consider family.

But the search didn’t stop there. After 37 days, ads and posters were no longer enough. The couple organized rescue teams, set traps and staked out sites with night vision goggles to see if they could spot Katie.

They even jogged around the area so that their sweat evaporating in the atmosphere would leave a familiar scent for Katie to follow.

Carole King even quit her job as a postal carrier to devote herself full time to the search for their best friend.

Almost another month went by, but after 57 days, the couple’s luck changed. A dog that looked like Katie was spotted running around the area, based on a tip from a nearby resident.

Carole went to investigate but apparently had just missed what could have been Katie. On the way back, she and a friend ran into a couple going for a walk and asked if they had seen Katie. By sheer luck, the couple noticed a dog that matched her description running behind them. They pointed in the direction they had seen the dog.

That dog turned out to be Katie. She was dehydrated and 15 pounds lighter. "Carole called her name, and Katie was a little hesitant at first. She just came running to her arms. It was so emotional … The day we've been waiting for," Jan Leland, a volunteer searcher and a friend of the Kings said. A tearful reunion concluded the almost 60-day search.

"I think it was the best decision I ever made to get my dog back ... I just know that she was out there looking for me, and I wasn't going to give up. No matter what," Carole said.