How did Gunnar get to the place where Jack and Early find him?

After Gunnar was injured, he crawled in the back of a truck headed north. The truck belonged to a veterinarian and Gunnar ended up at his place. The main put ointment on Gunnar's wounds and allowed him to stay in his barn for a couple of days. Since Gunnar could not go back to Portland, he went far away to the end of the world.