What letters are found after the name of a veterinarian?

This depends upon where the veterinarian received his/her professional degree from. In the United States, graduates from 27 of the accredited colleges of veterinary medicine use DVM (Doctor of Veterinary Medicine); graduates from The University of Pennsylvania use VMD (Veterinary Medical Doctor) because that is the name of the degree they earn.

Graduates of veterinary schools outside the United States may have different names for their degrees, but their education and knowledge are equivalent to US veterinary school graduates. The difference comes from the different post-secondary educational systems of various countries - some examples are MVSc (Master's of Veterinary Science) or BVSc (Bachelor's of Veterinary Science).