John Darby, manager of Granite Chief mountain gear in Truckee, said his oldest son, Alex, and Max the dog were hiking in the train tunnels near Donner Summit on Oct. 18 when the pet wandered away and could not be found.
John Darby searched for Max at at various ski resorts near the summit, as well as Squaw Valley. He went back the next morning and subsequent days for the next week but couldn't find the animal.
Jerrid Guerrero of Union Pacific Railroad spotted Max last Tuesday. He called the dog, which came to him.
When Guerrero drove over in his truck, the dog nearly jumped in.
"The dog was not going to let this guy leave without going with him," Darby said.
Guerrero called Darby on his cell phone because Max's tag had contact information on it.
Max was taken back home after 16 days alone in the forest. Darby said Max appeared to be in shock, but after a warm bath and some food he was fine. Max had lost a lot of weight, but he has since recovered.
Darby said he has no idea how Max survived without food or water. He said Max is not a hunting dog or an outdoorsy kind of pet. He goes on hikes sometimes, but he mostly likes to lie by the fireplace.
"I think it's going to be a while before he goes on a long walk again by himself," Darby added.
This article originally appeared on KCRA.com.