I don't know that if I should be giving you advice, since I'm not applying to vet school until this application cycle starts up, but my school situation started out very similar to yours.
Concerning your science grades...I think you should really evaluate
why you are getting the grades you are. Is it just science grades you are struggling with? Are you working too much? Are you having trouble with the basics? Are you not a good test taker? Once you figure this out, you can plan how to improve.
For me, there were several problems that contribued to my lower science grades my first few years of school. I figured out what they were and made changes to vastly impove those grades. I've been able to bounce back after having mulitple C's in my sciences from my first few years to getting pretty much straight A's in all my upper level sciences and pre-reqs like physics, microbiology, etc that I had left. It can be done...so you can do it!!
Also, realize that even with a slow start, you can bounce back. You may not get into vet school on your first try but you can always improve. Several people on this forum have been accepted with less than the "average" stats (3.5 GPA, 1200+ GRE, etc).
But I think the first thing you need to figure out is why you are struggling and then how to improve with what time you have left.