Must Love Dogs

Canines include dogs, foxes and wolves.

Here are the pets that should work:
[item=49912] (definitely works)
[item=49646] (definitely works)
[item=64403] (definitely works)
[item=12264]
[item=46544]
[item=85871]
[npc=63550]
[npc=63551]
[npc=62864]
[npc=62669]
[item=86570] (definitely works)
The achievement can be a little buggy, so it's hard to confirm what works and what doesn't.

If a raid member dies, the achievement will fail unless they're ressed to resummon their canine. In 25 man, only 10 need to have a pet. Many people have reported that the achievement is now possible with less than 10 people.

Note that the Fox Kit and Worg Pup can be traded, so if one player in the raid does not have any of these pets, they could be lent one (by putting the pet into a cage from the pet tab and trading it as a normal item).

Here are canines that were added to the game after the achievement, and will not work:
[npc=71023]
[npc=68654]
[npc=68662]
[npc=74402]
[npc=72160]
[npc=71014]
[npc=87111]
[npc=86422]
[npc=84915]

Finally, here are some fake dogs that definitely don't work:
[npc=61141]
[npc=14421]

As of 09/27/16 - Corgnelius does NOT count towards this achievement.

If you have ever done random dungeons you should have the Perky pug as the Looking For Multitudes , achievement rewards you with this pet after you have completed random dungeons with at least 100 random players