Ranchers don't have to stop to open and close gates if they have a cattleguard. This is Slim's house. Slim is a cowboy. Loper lives down the road. He is a rancher.
Ranchers own or lease the land.
Cowboys work for the rancher, usually for a monthly wage plus a house and beef. He and Sally May own the land, and Slim works for them as a cowboy. To a dog, of course, there is little difference between the two. In this scene, there's little difference between the two. This is pasture land which gives readers a clue that Hank must live on a ranch.