A South Portland woman who had been missing for nearly two days in Waterford was found alive Wednesday morning by a search-and-rescue dog and his handler.

Ruth Brennan, 77, was located in dense woods about a mile and a quarter from where she had last been seen at 10:30 a.m. Monday. She seemed in good health and smiled as she spoke with joyous family members before being taken to a local hospital by ambulance, said Cpl. John MacDonald of the Maine Warden Service.

Brennan was found by Elizabeth Fossett and her German shepherd Kobuk, members of Maine Search and Rescue Dogs.

“I just was exhilarated when she raised her head and said, ‘Yes, I’m Ruth,’ ” recounted Fossett, who lives in York with Kobuk.

Brennan, who has dementia, had been staying with family at a camp they rent every year. She was last seen walking toward Melby’s Market & Eatery on Route 35 in the Oxford County town of Waterford. She was found safe in the woods at 9:27 a.m. west of Jewett Pond Road.

The search involved 115 people – including 27 game wardens – with another 31 supporting the searchers, MacDonald said. It included crews on foot and a helicopter equipped with infrared equipment.

Fossett and Kobuk initially joined searchers at 8 p.m. Monday and continued until after midnight. They were back at 6:30 a.m. Tuesday, searching all day into the evening.

After two days, searchers may get concerned that a missing person might not be OK, MacDonald said.

“You think about the worst-case scenario,” he said. “The weather was on our side and she was in relatively good health for her age. Things worked out really well.”

On Wednesday, Fossett and Kobuk arrived at 7 a.m. and received GPS coordinates from the Maine Warden Service for her area of responsibility, Fossett said.

“Sometimes it’s just the luck of the draw – you’re given an assignment in an area where the person happens to be,” Fossett said. “We were given information she was a power walker, and the likelihood she was pretty far away (from where she was last seen). They gave me an outer perimeter assignment.”

Kobuk is an “air scent” dog, meaning he searches off-leash with his nose in the air and investigates when he catches a human scent. Such dogs tend to be used in outer-perimeter search areas to reduce the number of times they detect another searcher.

“Tracking” dogs, by contrast, will follow or search along the ground for a particular person’s scent, usually on a lead held by their handler.

Just before 9:30 a.m., Kobuk caught a scent. Search conditions had improved, with a steady breeze blowing smells toward him from as far as a half-mile away.

Fossett saw the dog catch the scent and take off running to investigate.

“I call him the Ferrari of the woods. He’s fast,” she said. Kobuk wears a GPS device on his collar so Fossett can keep track of him. When the dog returned, he gave a trained bark indicating that he had found someone, and was then rewarded with a toy.

Fossett gave a second command for the dog to show her the source of the scent, and found Brennan when she came down off a ridge into a low-lying area of dense growth. Fossett gave her water and snacks, and radioed the warden service command post with the coordinates of their location.

The warden service sent a helicopter overhead, and eight to 10 wardens carried Brennan out to get medical attention.

Fossett said it felt great to help find someone who was missing and reunite them with their family.

“We train hard for it,” she said. “I’m just thrilled today was my dog’s turn to find someone – to bring Ruth home.”

For Kobuk, the ultimate reward came from Brennan herself, who told the dog how handsome and big he was. Then she picked up his ball and threw it for him to chase down.

“For him that’s the ultimate,” Fossett said, “to (get to) play with the person he finds.”