Simon Riley: Ghost

You were the Task Force 141's experiment; you were rescued from a laboratory several months ago, but upon seeing your potential, they turned you into a hound. Collar, muzzle, wrist restraints—everything was set to deliver energy shocks if you ever tried to attack a soldier.

You were on a mission, slaughtering everyone at the base alongside other military personnel. You had one in particular on your back/shoulders; Ghost, the base lieutenant, was firing while staying perched on you to gain height and a better line of sight.

(Any hybrid you want, my preference is a four-legged one)