Dogs can be called in by a player as a 7-killstreak in the multiplayer mode of Call of Duty: World at War. The dogs spawn and attack enemy players on the map for 60 seconds. Friendly dogs appear as German Shepherds and enemy dogs appear as black Belgian Shepherd Malinois. Interestingly the PC version constantly displays Axis dogs as German Shepherds whilst Allied dogs are Belgian Shepherd Malinois.
The dogs can be killed, but will continue to respawn until the 60 second cycle has ended. By default, dogs have 100 health. Dogs attack by lunging and biting at enemy players. In standard modes, players with more than 90 health points can survive up to two dog lunges before dying, but in Hardcore players die instantly even with Juggernaut. Killing a dog will give a player 3 XP depending on the game mode, but will not count as a kill or an assist. However, in Team Deathmatch and Free-for-All players score 3 and 2 points respectively, making it possible to actually win the game with fewer kills than would otherwise be necessary. For this reason, it can actually be detrimental to call in Dogs in these gametypes. Dogs rarely go into water, cannot climb ladders and never attack players in tanks.
Attack Dogs make a return in Call of Duty: Black Ops, and have been upgraded to an 11-killstreak reward in multiplayer. German Shepherds (friendly) or Belgian Shepherd Malinois (enemy) will spawn for a set period of time after activation. Four dogs initially spawn, with four reserve dogs. As the first four are killed, they are replaced from the reserves, giving a maximum of eight dogs over the time the kill streak is active. The dogs now kill with one bite, which is likely due to the challenging task of acquiring 11 kills. Dogs are also attracted to gunfire, so a good thing to keep in mind would be to try and leave things quiet for a while. Ghost Pro does not make the player invisible to them. The most effective ways to counter dogs are to stay in an area with long range sight-lines and preferably with a wall behind the player in order to be able to gun them down or climb to an area only accessible by a ladder. Such spots are a red cable car on which a player can jump to avoid dogs on the multiplayer map Summit, the elevated sniping position in the middle of the map on Firing Range and a sniper positon on Jungle on the rock.
Attack Dogs (now called K9 Unit) are a scorestreak in Call of Duty: Black Ops II.
The K9 Unit requires a scorestreak of 1700. The K9s are identical to their Black Ops counterpart except they now wear a vest, to fit with the future setting of the game. They don't however add any additional health to them. Killing a K9 in Black Ops II now rewards the player with 50 points per kill towards their scorestreak. Dogs will not attack any player that is in water. Hardcore does not reduce the dogs' health.
Although dogs cannot climb ladders, they have been known to leap up to six feet high to get on top of objects, such as the grassy-jungle-like walls on "Courtyard" and can even jump the entire ladder on the balcony in "Dome."
Dogs are affected by Tabun Gas. Proof of this can easily be seen in the KillCam if a player gets killed by a dog hit by such a grenade. The dog's vision will be distorted in much the same way that a human player's would be.
If a dog jumps off the map it may fly back up a few seconds after falling, however this is rare for either event to happen as the AI is programmed not to do this.
Call of Duty: Black Ops
The Strategy Guide states that Enemy Attack Dogs will not target the player if said player has Ghost Pro.
On the multiplayer level Berlin Wall, dogs can travel through No Man's Land without being shot by the guard towers.
Nova Gas will affect dogs. Dogs in the gas will stop and scratch at their eyes for a moment before continuing their attack.
It is possible for the player to be killed by their own dog. If the player walks in front of a friendly attacking dog the player will die. The kill feed states that the player committed suicide and shows a dog emblem.
The player can be killed by friendly dogs that were called in by another player, even on Core modes. If this occurs on Core it states the player committed suicide and the owner of the dogs is not penalized.