Barkley

Barkley is one of eight sled dogs you can adopt at the beginning of the game.

Barkley's Quest
When you go to check out Barkley, your character notates that his owners say he "gets into fights but is loyal to his Musher."

If you pick Barkley, when you have the encounter with the wolf while sledding, instead of being bitten by the wolf, Barkley will hop between you and the wolf and try to fight him, getting hurt himself in the process.

After this event, you bandage up Barkley. Later on, Chomper will encounter a squirrel and chase after it. The squirrel will be sitting on a log and Chomper will be yelling at it, but the squirrel will turn to try and run at you, but Barkley will then hop in and kill the squirrel before it can "attack" you.

You scold Barkley, telling him he needs to learn to bark instead of bite. You then have the choice of teaching him then, or leaving and moving on. It order to continue the quest, you should teach him then and use the command "Bark!" in order to help him learn how to bark.

Finally, your sled will encounter a moose that will run straight at you and knock you over. Barkley, because you taught him to bark, will then yell at the moose and scare it off, ensuring that neither you nor him get hurt in the process.

Doing all of this will result in receiving the Barkley sticker when you reach the cabin that run.

Barkley's Abilities
Barkley will help protect you from certain threats, such as wolves, moose, and squirrels. This can be helpful, as you injure yourself less, however he can injure himself in the process on occasion.