Gregory D. Herndon was originally born in New York but grew up mainly in Virginia, until he went to North Carolina State University. Upon graduating from NCSU, he spent a year at the University College Dublin, School of Veterinary Medicine in Ireland before entering the DVM program at the University of Tennessee, College of Veterinary Medicine. It was during his second year in veterinary school that he decided to pursue a career in small animal surgery.
After graduation, he successfully completed a small animal rotating internship at the VCA West Los Angeles Animal Hospital. Upon completion of his internship, he was accepted into the small animal surgical residency program at Colorado State University, Veterinary Medical Teaching Hospital, and completed his last two years of his residency at the University of Tennessee, College of Veterinary Medicine.
After completing his residency, he passed his board-certifying exam in small animal surgery in 2003. He has spent his career performing surgery in a private practice setting and some time in academia as a professor of Small Animal Surgery at the University of Montreal, Faculty of Veterinary Medicine. He returned to the US in 2018 to be closer to his family.