DD

DD or D-Dog (short for Diamond Dog) was the pet of the private military company Diamond Dogs during the 1980s. Like his owner, Venom Snake, the animal wore an eyepatch over his missing right eye.

As a puppy, DD lost the use of his right eye and was presumably an orphan. The puppy was found alone by Venom Snake during a mission in 1984. DD was later taken by Fulton Recovery to Diamond Dogs' Mother Base, his new home. After DD had fully grown and been trained for a combat support role, Venom Snake had the animal accompany him on his missions, at the suggestion of Ocelot.