Travis and Old Yeller work together to mark the hogs using clever teamwork. Marking hogs is very dangerous work. It involves making a distinctive cut in a baby pig's ear. Travis knows the danger involved: he says, "I've worked with papa long enough to know that anytime you mess with a wild hog, you're asking for trouble" (Chapter 9). The risk comes from separating the piglets from the adult hogs, who are very keen to protect their offspring.

When Travis and Old Yeller come across a pack of hogs, Old Yeller antagonizes them into chasing him into a dead end formed by large rocks. Travis then climbs a branch of an oak tree that juts over the cornered pigs. While the hogs are distracted by the dog, Travis uses a lasso to snare one young pig at a time to raise it up into the tree where he marks its ear. By each marking their pigs' ears in this way, every settler knew exactly which hog belonged to whom.

The work takes about an hour to complete. The hogs are so distracted by Old Yeller that they do not pay much attention to Travis in the tree above them. Occasionally, the larger hogs break ranks and charge at Old Yeller, but he is able to stay just out of their reach each time.