Sounds like your in a pickle!
My mother has always told me, "If you enjoy the work you do, its not work at all!"..
So, from what your telling us, your only "putting up" with the Chem course because you were unsure as what to do/take.
If I were in your position, firstly, go and buy a new pair of shoes, you will feel better, hehe, then, have a serious chat with your director of studies, as you've indicated you like the Uni your in, MAYBE you could swap courses in the new academic year instead of worrying about the next three years doing Chemistry.
Your an amimal lover, ofcourse, but you need to ask yourself and be completely sure whether you really want a career like Vetinary stuff etc..
Again, I'd have a good long chat with your director of studies, this person would have seen loads of people in your position previously, and no doubt will have some good advice and knowledge to pass on to you..
Hope this has helped!