Oswald and some witnesses who stopped to help started searching the area for Tilly, but there was no sign of him after 10 hours of scouring the area.
The family posted about Tilly on social media and search parties continued to look for Tilly, but the dog didn't turn up until Tuesday, when Tyler Potter and her brother, Travis Potter, noticed one of their sheep herding dogs appeared to have darker fur than usual.
The siblings' other brother, Zane, attempted to call the dog, Hooey, later in the day, and became suspicious when the canine didn't respond to his name as usual.
"Hooey really comes right away when you call him, and this dog put its ears back and started running off," Travis Potter told the Spokesman-Review newspaper.
The Potters said they soon realized the dog they had thought was Hooey was actually Tilly, the canine their grandmother in California had seen on social media and told them to watch for after the crash, which occurred only 1 1/2 miles from their property.
The Potters captured Tilly and turned him over to a Kootenai County Sheriff's Office deputy who was searching for the missing dog in the area.
Tilly was reunited with the Oswald family late Tuesday morning.
The Potters and Oswalds agreed Tilly most likely was following his instincts, and was drawn to the farm by the opportunity to herd sheep.
"He'll herd anything," Oswald said. "When I go to the dog park, he tries to herd the people into one group."