Attack dog

An attack dog is any dog bred, trained or used for the purpose of attacking a target either on command or on sight. Attack dogs generally receive extensive military training in tracking and combat techniques, making them formidable close-range fighters, and difficult to elude. They have been used since the time of the Greeks and the Romans, where they wore spiked collars and charged against enemy lines.

World War II
The Soviets once attempted to train so-called anti-tank dogs, nicknamed "bomb dogs," to deliver explosives to enemy tanks by diving beneath them and detonating them as they retreated. However, though they were successful in operating in this manner, the plan backfired when the dogs attacked Soviet tanks rather than German tanks.

During Operation Snake Eater, Naked Snake encountered Great Danes that were being used as attack dogs by GRU. Their barking would alert enemy patrols to an intruder's presence and they would also try to pounce on and bite them. There was no easy way to shake them off as they would pick up an intruder's scent, but smoke grenades helped in fending them off. Despite their large size they could fit through narrow ducts, as demonstrated in the sewers beneath Groznyj Grad.

Great Danes were also utilized during the takeover of the San Hieronymo Peninsula, this time by FOX and Red Army soldiers. They were sometimes seen guarding areas in the town and were also used during the claymore incident at the hospital, after the soldiers had departed.

During Operation Intrude N313, German Shepherd Dogs were used to guard areas of Outer Heaven in which no human soldiers were stationed, such as the inner courtyard and basement of Building 1. They were often relied upon to take care of any intruders themselves.

Although not specifically used as attack dogs, the wolf-dogs on Shadow Moses Island tried to attack Solid Snake during his mission there. The Sons of Big Boss had originally considered killing the wolf-dogs, until Sniper Wolf stopped them. Despite their feral nature, they seem to take kindly towards Meryl when they approach her.