I didn't though and got C's (and 1 C-) in 3 semesters of chemistry and 1 semester of biochem and I am in vet school right now. There is a bigger picture, but don't lose hope and don't give up if you think your grades aren't competitive enough. The reason people tend to focus on these is because many schools assign points and the majority go to GPA and GRE.
My post was in no way trying to say that if you don't have other things going, Cs will devastate your chances. In fact, it was kind of the opposite. I find it very annoying when people forecast one another's chances based solely off GPA and GREs. I know schools put a lot of emphasis on them. But it's not necessarily the whole enchilada. In fact, as you can see below, in most cases GPA/GRE only accounts for half of the points that schools look at. Granted it's objective and not really subject to interpretation. But in no way do I think you can look at someone's GPA/GREs and tell whether or not they have a good chance. As supported by the information below (drawn from the 2008 VMSAR, for the US schools that list this information). Our information is weighted as follows:
UC Davis (50 % GPA/GRE; 50% rest)
Grades (25%), Test scores (25%), Personal statement/essay/animal & vet experience/references/other (30%), Interview (20%)
Cornell (50% GPA/GRE; 50% rest)
Grades (25%), Test scores (25%), Animal & vet experience (20%), References/essay/quality of academic program/non-academic activities/non-cognitive attributes (30%)
Kansas State (70% GPA/GRE; 30% rest)
Prereq sci GPA (30%), Test scores (40%), Interview/references/animal & vet experience/leadership/essay (30%)
Louisiana (70% GPA/GRE; 30% rest)
GPA for prereqs (32%), GPA of last 45hrs (20%), Test scores (18%), Animal & vet experience/references/essay (15%), Interview (10%), Committee evaluation (5%)
Missouri (50% GPA/GRE; 50% rest)
Grades (45%), Test scores (5%), Animal & vet experience (10%), Interpersonal skills (15%), Work ethic (5%), Life experience/diversity (5%)
Ohio State (45% GPA/GRE; 55% rest)
Grades (35%), Test scores (10%)
Interview (55%) (where they evaluate: academic improvement vs. difficulty/communication & interpersonal skills/social & community activities/ work record & financial responsibility/motivation & commitment to vet med/comprehension of vet med/knowledge of & exposure to animals/references)
Purdue (54% GPA/GRE; 46% rest)
Grades/test scores/overall academic performance (honors, study abroad) (54%)
Animal & vet & research work experiences/extracurriculars/essay/overall presentation of app materials/references/interview (46%)
Tuskegee (I have no idea since they added wrong)
Grades (60%), Test scores (2%), Animal/vet experience (1%), Interview (15%), References (1%), Essay (1%)
... which only adds up to 80%...so I have no idea what's going on here
VMRCVM (50% GPA/GRE; 50% rest)
Cumulative GPA/req sci GPA/last 45 hr GPA/GRE aptitude (50%)
Animal & vet experience/research, industrial, and commercial experience/activities, achievements, and awards/essay/references (25%)
Interview (25%)
University of Wisconsin (60% GPA/GRE; 40% rest)
Undergrad cumulative GPA/pre req GPA/Most recent 30 hrs GPA/GREs (60%)
Animal & vet experience/other preparatory exp./extracurriculars/personal history/references