Thought I'd update this thread...I found this recent scienceblog entry particularly interesting.

More thoughts on animal research: Pets & wild animals benefit, too.

Couple of quotes from the entry:

"Every year people adopt pet dogs, cats, birds, and other creatures and take them to their local veterinarians for all the usual vaccinations and exams. The usual vaccinations protect your pets from diseases like rabies, distemper, Feline Immunodeficiency Virus, and Feline Leukemia. But it's not just pets that get protected by vaccines. Agricultural creatures: fish, chickens, sheep, cows, pigs, and horses receive vaccines and increasingly, wild animals are getting vaccinated, too."

"Like the vaccines produced for humans, the vaccines produced for animals must be pure, potent, safe, and they must work. This means that all the vaccines that are given to your pets, agricultural animals, and wild animals were tested on lab animals to make sure that the vaccines are safe and that they work."

The comments and links in the comments are pretty interesting and informative as well.