Broken Tooth
From WoWWiki
Broken Tooth was once considered the ultimate hunter pet mostly for his capabilities in PvP combat. He was sought after for his 1.0 attack speed, which was the quickest in the game. However, since pet speed normalization in patch 2.0.1 he has lost this ability and is no longer considered a pet to strive for.
In the past, his 1.0 attack speed greatly delayed the spells of enemy casters in PvP. Broken Tooth was also effective for Beast Mastery hunters previous to Patch 1.7, since Broken Tooth was the most effective pet for the Frenzy and Spirit Bond combination before Spirit Bond was changed into its modern form.
