A medical forum does seem to be a good idea, on the surface. However, another approach would be to have certain relatively common ailments listed in a FAQ page or the like to see if people can clear up their own problems. A section for getting rid of mites, a section on what to do for bad sheds, etc. More serious conditions shouldn't be dealt with whatsoever. After all, the answer will usually be "go to a vet", which is what should be done in the first place rather than waiting for someone you don't know and who's never actually seen your animal or its enclosure tell you what to do.
Also, I can't say as I blame vets/vet techs for shying away. It's their livelyhood on the line after all. If someone came along and told me that if I helped someone set up a satellite receiver or put in a subscriber amp I could be sued, or somehow barred from working with telecommunications, I'd be leery of helping others too. Telecom is what I do for a living after all, and it's hard enough finding a job these days without having any black marks on your record.