Squanto is quite well groomed and is a pure breed dog, a rarity in Denver. He is also named and has some form of identification. He was separated from his previous owner and wandered the streets of Denver, looking for him until he found Harriot.
Despite the effort gone into keeping him presentable, Squanto does sport a number of battle scars and isn't exactly perfect like a scavengers dog or any of the incarnations of Dogmeat.
Squanto isn't afraid of expressing himself, whether he barks happily or whines in response to pain or some other unpleasant sensation.
He is incredibly loyal to those he follows, going as far as to put himself into harm's way for them.
Behind the scenes
Squanto is a native American name, the dog shares the name with a historical native American figure, who assisted the pilgrims when they were surviving the land. There are a number of similarities between Squanto and his Native American counterpart.