I have a PhD and started vet school this year. However, I decided about halfway through my PhD that I really wanted to be a veterinary pathologist, based on what I was doing for research and talking to others in the field. I finished the PhD and got accepted my first year applying. My clinic hours were low, but I explained in my PS that I wanted to do research and pathology.
I agree with others that it will really depend on what you want to do. For me, it's getting to the point in the vet path field that a PhD is HIGHLY recommended. Overall, my time spent completing both degrees and a residency will be about 3 years longer than if I had done a combined residency/PhD program. That is a big con though, that I can't really apply to combined programs now. I think it boils down to what aspect of veterinary medicine do you want to do? Could you wait to get a PhD afterward? A PhD is a HUGE time commitment and you shouldn't do it just as a means to get into vet school.