I think he was a mutt.

[Danny wasn't entirely sure about breed with Cujo. He'd probably been one of the usual guard dog breeds once. But now that he was a ghost...

Well, he was mostly just green and dog-shaped.]

But he kind of had one of those personalities, you know? One minute a puppy that just wanted his squeaky toy, and the next moment charging off and getting into trouble.

[And also the size of a house. ]