What kind of dog is Billie?

Billie is Joe's dog brother. He is good-natured, friendly and eager to please but still weary of his place in the pack. Billie collapses after repeated cruelty from Hal. Billie eventually dies when an angry Hal breaks his head with an axe.

I think Billie and Joe are both Siberian Huskies and lol when Hal hits Billie in the head with the ax.

Stephen, you're right. Bill and Joe are brothers, and they are both pure bred huskies.