My grandfather, Bob Cook, who has died aged 94, was a scientist and artist. He was a pioneer in equine veterinary medicine, who challenged horse-training tradition with research that suggested bits cause pain, suffocation and the behavioural problems they are meant to solve.

A veterinary iconoclast who spent decades fighting to “unshackle the horse”, he proposed that bit-free riding could eliminate conflict behaviours while improving performance and rider safety – findings that may ultimately transform equestrian sport. His final article will be published in Horses and People magazine.

Born in Wolverhampton to Elsie (nee Little) and Francis Cook, a business manager, Bob went to Bromsgrove school, Worcestershire, and then the Royal College of Veterinary Surgeons in London. After gaining his doctorate from Cambridge University, he worked as a vet in Kenya in the late 1960s and Kuwait in the 90s. Sheikh Mohammed bin Rashid al-Maktoum of Dubai and Queen Elizabeth II were among his clients.

Veterinary medicine proved doubly rewarding, as he met Margaret (nee Bowen), who was the secretary of a veterinary practice where they both worked in Chippenham, Wiltshire, and they married in 1965. She had three sons from her first marriage.

They moved to the US in 1978, where Bob helped to set up the Cummings School of Veterinary Medicine, Tufts University, in Boston, Massachusetts, serving as associate dean, and later professor emeritus. The bitless bridle he developed, still used worldwide, supported his research, showing that removing pain makes better horses and better riders.

Bob brought eloquence to scientific writing. His hundreds of publications stand out for their clear, engaging style. An accomplished painter and calligrapher, he approached every field of knowledge with the rigour of a scientist and the wonder of a scholar. He loved music, poetry, art and architecture. Shortly before he died, he described himself as “jubilant”.

A swimmer, runner and yoga practitioner, he still cut a dash on the dancefloor into old age.

A son, Nicholas, died in 2003 and Margaret died in 2018. Bob is survived by two sons, Peter and Robin, his grandchildren, William, Tim, Madeleine and me, and his brother Roger.