Veterinarian
From Memory Alpha, the free Star Trek reference
A veterinarian is a person who specializes in the medical treatment of animals.
The Denobulan Phlox possessed six degrees in interspecies veterinary medicine. When on the Enterprise NX-01, he made use of his knowledge by operating on Porthos, Jonathan Archer's beagle. (ENT: "A Night in Sickbay")
After the USS Voyager harmed the nucleogenic cloud being and planned to return to treat it, Neelix complained about the action to Kathryn Janeway stating that he wasn't a veterinarian. (VOY: "The Cloud")
