There's a bit more to it than that.
If you take a look at ISU's pre-reqs (
https://vetmed.iastate.edu/student/...he-college/pre-veterinary-requirements/course), you'll see that several courses have an asterisk next to them. The asterisk denotes that these classes are used in calculating the science GPA. These include gen chem 1 and 2, organic chem 1 and 2, biochem, physics, general biology 1 and 2, genetics, and mammalian anatomy/physiology. Altogether, that's five chemistries, one physics, and four biologies. So your chem grades, if they're really poor (so, say, mostly Cs) definitely have the potential to lower your science GPA by quite a bit. It may be something to keep in mind if they're not the best, but I wouldn't let it deter you from applying entirely if the grades you've got in the rest of the included science classes are solid. Lord knows my marks in chem weren't the greatest in the world... two Bs (gen chem 1 and organic chem 1), two Cs (gen chem 2 and biochem), and two As (medicinal chem, which admittedly isn't counted here, and organic chem 2). But my other sciences were pretty much all As, so YMMV.