What does the veterinarian designation dact?

DACT stands for Diplomate of American College of Theriogenologists, basically when a veterinarian completes the course of study and residency requirements and passed the Certifying Board exam, they become a Theriogenologist, or reproductive specialist. Not unlike when a physician completes a surgical residency, then takes additional training to become a cardiothorasic or hand ororthopeadic surgeon, completes the board exams as such and receives the additional honorific for that.