A documentary was shown at 07 Sundance called "Zoo." While it is about a man who has sex with his horse and dies after one of the interactions, it goes deeper into the cultural and psychological reasons behind the people. It's supposedly handled quite seriously and sympathetically.

http://www.imdb.com/title/tt0874423/

It's screening in LA the week of May 4 and I'm definitely going because I'm fascinated by the whole mental evolution and humans varying relationships with animals - and yes, that would include me and all you crazy cats.

I'd love to not go alone, so...come to LA now, ya hear?