Just in case everyone thinks that the 1 year masters is a ticket to getting in, think twice before signing up. I was told by multiple ad com folks at Missouri at my 3 year research based masters in biology was NOT a by into the program. And mine was like a mini PhD, not just take an extra year's worth of classes kind of thing. So just be careful you're not signing up for something that's expensive and that may not help much anyways!
The ad coms know that in grad school (at least research based), your grades in classes are not particularly important. Most professors give out Bs in the very least (most...) as they know if you get below a 3.0 cumulative, you're out. So while you can't slack, you'll likely do better just because class work is not the focus.
I also personally get really irritated having the "same" degree (an MA) for doing much more work and I really wish these plan B options had a different degree designation as most seem identical to post bacc work (which is essentially doing another senior year), you just get a piece of paper for it. With the popularity of them, I also get really irritated by people who have asked me straight up, "oh, did you get a masters first because you couldn't get in the first time?" Uh...NO.
I actually enjoy my area of research, thanks! I wasn't even pre-vet until after I was well into grad school.
It just irks me that if you get a BA/BS in biology somewhere, everyone knows that you'll have taken similar amount of classes and the degrees are fairly similar, perhaps unless you go to a real small liberal arts school, whereas the plan B type MA/MS programs are not in the same level as my MA. I'd say if you want a masters in biology, etc, do the research experience, do the thesis, do the grad level classes. That'll help you a lot more in the long run than just a year of classes. And the PhD faculty during vet school will respect you a lot more if you've done real research and you understand from first hand experience the research method. You're more on their level as peers, which is cool.
I did some pretty in depth research during undergrad (definitely a lot more than being a dish bitch in the lab!), but it's not nearly to the same level and intensity as grad school. If you just want extra classes to help get into vet school, do an MPH especially if public health is an interest (and even some of them require research) or a post bacc. I hate to have it boil down to saying "my piece of paper is worth more than your piece of paper," but yeah...and it may not even help in the end!