at 28 Jun 2006: 21:49
No! Because you view beastailty as a selfish act, you are insisting that consent be nessesary. If the zoophile did not get anything positive out of the experience (i.e. pleasure), it could not possibly be a selfish act. Thus, the act no longer becomes exploitive and consent becomes irrelivant even in a purely human arena. The focus was not on pleasure. It was selfishness.
BTW, you didn't answer the question about vets masterbating there "patients".