William Thomas Riddle, DVM, 74, co-founder of Rood & Riddle Equine Hospital and an internationally recognized authority on equine reproductive medicine, died on Sunday, Sept. 20, 2026, at his home in Versailles, Kentucky.

The son of a veterinarian, Riddle was born and raised in Greenville, South Carolina, and graduated from Wake Forest University in 1974 and the University of Georgia (UGA) College of Veterinary Medicine in 1978.

After earning his veterinary degree, he traveled to Lexington, Kentucky, to serve an internship with Don Witherspoon, DVM, at Leslie Combs’ Spendthrift Farm. Afterward he spent another three years working at Spendthrift.

In 1982 Riddle joined William Rood, DVM, in his ambulatory practice in Lexington, forming Rood & Riddle. In 1985, Rood & Riddle purchased land and broke ground for their new hospital.

Riddle was honored with numerous awards and distinctions during his life, including serving as president of the Kentucky Association of Equine Practitioners, the Society for Theriogenology, and the Theriogenology Foundation.

He received the Steiner Award for Excellence in the Practice of Theriogenology and was an honorary member of the American College of Theriogenologists. Additionally, he was recognized as a Friend of the University of Kentucky Ag Equine Programs and received the UGA College of Veterinary Medicine Dean’s Distinguished Service Award and the Distinguished Educator-Mentor Award from the American Association of Equine Practitioners.

Riddle founded Hats Off to Kentucky’s Horse Industry Day, which celebrates the horse’s impact on the Commonwealth of Kentucky. He was appointed to the Kentucky Horse Racing Commission by Governor Andy Beshear in 2023. His obituary also credits him with guiding young veterinarians through his example.

Riddle was the first to recognize and report the 2001 equine abortion outbreak, known as mare reproductive loss syndrome. After he retired from busy breeding farm practice, he served as the director of marketing for Rood & Riddle.

“I was saddened to learn of Dr. Riddle’s passing,” said Rood, who was also his longtime friend. “I will miss Tom’s wise counsel, his entrepreneurial spirit, and his gentle ways. He was the best partner, and together we accomplished more than we dreamed. Tom will be missed.”

Riddle met his wife, Margaret Alexander Riddle, while working at Spendthrift. They married in 1981. His obituary describes him as a true family man who loved horseback riding with Margaret on their farm, spending time at the beach in South Carolina, and being with his wife, children, and grandchildren.

In addition to Margaret, he is survived by his daughter, Peden Riddle Fraley (Bryan); his sons, Alexander Landstreet Riddle (Emily) and William Davis Riddle (Neely); his sister, Jessica Riddle Curlee; his brother, John Newby Riddle; and his grandchildren, Adeline Davis Fraley, Harrison Anne Fraley, John Woodford Riddle, Charlotte Louise Riddle, and another grandson on the way, William Thomas Riddle II.

A gathering of family and friends will be held 4-7 p.m. on Monday, Sept. 28, at Clark Funeral Home, Rose Hill, in Versailles. A memorial service will be held at 11 a.m. on Tuesday, Sept. 29, at the Church of the Ascension in Frankfort, Kentucky, with Rev. Mr. Peter Doddema officiating.

In lieu of flowers, memorial contributions may be made to the Bluegrass Farms Charities, P.O. Box 12252, Lexington, KY 40582, or donated to www.bgfcky.org.