Bred and infected from an extinct chain of Argentinean pit dogs for the purpose of killing encroaching werewolves in an urban environment.
The plastic milk jug holds water that he can guzzle as his metabolism is so accelerated (he sweats profusely and pants simultaneously) that he constantly needs to rehydrate and eat.
The baseball bat has sharp strips of jeweler's silver hammered into it with wire wrapping around to prevent the bat from splitting. This tool is specifically used on werewolves.