Two-Legged Dog Instagram Star Beats the Odds and Survives Dramatic Car Accident During Family Vacation

"Duncan has always lived life on level 10 — he's one tough, incredible dog," Duncan's owner said.

A two-legged dog beloved by thousands on Instagram and YouTube for his determination and happy spirit, has beaten the odds again — this time while on a Yellowstone National Park vacation with his adoptive family.

Duncan Lou Who (named after Cindy Lou Who in How the Grinch Stole Christmas), a four-year-old boxer, was born with his rear legs fused together and a severely deformed pelvis, but he hasn’t let these differences slow him down.

His owners, Amanda Giese and Gary Walters, founders of Panda Paws Rescue, a pet adoption service in Vancouver, Washington, had just started their vacation in Yellowstone on the evening of Aug. 4th with their two children, Beast, 15, Jade, 13, Duncan, and two other dogs, Bullfrog and Garnet, when their car hit a buffalo that had wandered onto U.S. Highway 20, near a cabin they were renting in Island Park, Idaho.

Beast, who was driving (he has a learner’s permit and was getting in some nighttime practice), acted quickly and veered to the right instead of into oncoming traffic, hitting two power poles and rolling the family’s truck several times. Although everyone escaped with minor injuries, including Bullfrog and Garnet, Duncan was ejected from the vehicle and went missing.

“I was afraid that he was lying in the brush somewhere with broken bones or maybe dead,” Gary, 46, tells PEOPLE. “Once power crews put the poles back up and told us it was safe, we turned on flashlights and started looking.”

While an EMT drove Amanda and Jade back to the cabin, where they put out a message about Duncan on their nonprofit’s Facebook page, Gary and Beast searched through the night, joined by EMTs, police officers and witnesses who had stopped on the highway to help.

By Saturday morning, another 30 people showed up to search, but they could find no trace of the spunky boxer, whose first trip to the beach was a YouTube hit with more than 7 million views.

Then a local man driving near a rock quarry three miles from the accident site, saw a two-legged dog wandering around. At first, he thought nothing of it, says Gary, until he stopped at a gas station and heard people talking about the search for Duncan.

“He got in touch with me,” Amanda, 34, tells PEOPLE, “and everyone then refocused their search near the quarry. We were thrilled and amazed that Duncan had traveled so far on his own and had managed to survive the night in bear and wolf country.”

When one of the searchers spotted Duncan 20 feet from a fence line, he quietly waved over Jade to call out to the canine.

“I said, ‘Duncan! Do you want a cookie-ookie?’ ” Jade tells PEOPLE, “and his ears perked right up. Then he ran over and jumped straight into my lap.”

Her family’s two-legged dog has survived several brushes with death, ever since he was adopted when he was three months old.

“He survived having his fused legs amputated, he has autoimmune issues and his heart has stopped twice,” says Amanda. “Both times I was able to do CPR and bring him back. Duncan has always lived life on level 10 — he’s one tough, incredible dog.”

Although their family vacation was cut short (it took several days to line up a rental car before heading back to Washington), no matter, says Gary.

“We’re all together, and we’re all alive,” he tells PEOPLE. “This is not only a story of Duncan’s survival — it’s a story of humanity. We can’t thank people enough who dropped what they were doing to come out and help look for our dog.”

As for Duncan, “we need to pick him up a jar of peanut butter,” he adds. “I’d say he deserves it right now.”