Lupine Form is the last form before reverting back through the others to human again. It leaves no trace of it's former human self, and instead, leaves the transformed with natural wolf-like features. The character is at it's fastest in this form. Use of hand movements is reduced and eyes see much better in the dark than during the day, but their sight is perfect none-the-less. Hearing is increased as well and they are the most calm or most fierce because their strategy skills also improve (this is believed because of the better hearing and sight). Communication is at it's minimal unless the character has learned telepathy, however, most of the pack just uses body language to communicate once in this position. Howls are natural forms of communication as well for position and strategy.
( This picture was cut from a line of pictures from this site. )
Sizes of the Lupine form majorly depend on what natural rank the character is. Alphas tend to be bigger than the betas and definitely the omegas.
The leader can be any size, but is generally the biggest (because he must theoretically be able to fight any one member of the pack and win) Some have been recorded as being as large as Moro, Reita's Lupine form is as large as the pups, and others more frequently range under the pups, like Jon Snow's Ghost and omegas are generally the natural wolf size.
If you cannot see the link attached to 'this', then this is the actual link:
http://jiggsokeken.deviantart.com/art/Werewolf-The-Apocalypse-Garou-Forms-280620066