Sidenote, but I really hate that about some vet schools. I worked as a pet food donation coordinator for one of our animal welfare clubs while in vet school, and when SCAVMA/SAVMA/whatever found out I wasn't a member of theirs (I don't particularly like the AVMA), they threatened to kick me out of my position (in a totally different club!) unless I joined. Bunch of snots. Any new clubs also had to be approved by SCAVMA, which added a second coat of of stupidity.
(Long story short, I resigned my position rather than let them bully me into joining. I didn't like some prissy student org telling me I can't perform voluntary community service with another club unless I kiss their behinds)