Are you a resident of Pennsylvania? You have a stronger chance of admission to a vet school in your home state as they hold the largest number of seats for their instate students. The certificate program will not necessarily give you an advantage in admission. Do you have all of the prerequisite courses required for vet school admission? The next thing on the list is to acquire the number of hours of direct animal care under the direction of a veterinarian that the vet school requires. They also look for leadership in community and demonstrated skills outside the area of veterinary medicine. These things, plus a high GPA and high GRE score and being an instate resident will help in vet school admission. I think that a job in a veterinary office will allow you to understand what it means to be a vet, how to handle not only your patients but to be able to communicate with your clients owners. This is a very important concept that vet schools want their students to understand.