I would think that using something like alpaca or wool would be the complete opposite for a vegan. Using the hair of an animal isn't killing the animal, its just giving it a buzz cut and making it feel better in the warm summer months. It would be inhumane to allow an animal to suffer by letting it keep a thick coat in such heat.
But to each his/her own I guess.
My knitting blog: Yarnolicious
Oceanblue28 on Ravelry
So many things to knit, so little time!!