There was one by Azrael, I thought? I can't find it now.

Hellhounds. (http://tfwiki.net/wiki/Hellhound) I have the silly urge to write a fic where Spinister brings a puppy back to train it as a tracker to 'tree' Autobots for him, and Needlenose is annoyed because Needlenose is a cat person and does not like puppies. Especially puppies of the damned.