Animal Welfare group Paw Justice is calling for a ban on bareback rodeo riding, saying the sport invariably leads to animal suffering.
The group is basing its claim on a slow-motion analysis of modern bareback rodeo - where the rider lies flat on the horse with their feet above the horse's neck and shoulders.
"At normal speed the rider looks like he's holding on for dear life," says Paw Justice Co-founder Craig Dunn.
"When you slow it down you can see he's deliberately and forcibly slamming his spurs down on to the horse's neck and shoulders to make the horse buck more and thereby receive higher marks from the judges."
Elsa Flint, a behavioural veterinarian with 26 years' experience, said the action would create mental and physical trauma for the horse.
"The spurs aren't sharp so won't pierce the skin. But they will cause significant bruising deep into the muscle," says Flint.
But Glenn Campin from the NZ Rodeo Cowboys Association said the criticism is misinformed and the modern feet-forward technique is designed to make it harder for the rider to stay on the horse and in no way harms the animal itself.
"The spurs are blunt and on free-running rails which stop them grabbing and gripping," he said.
"If you watch the slowed-down video the skin doesn't ripple in the neck, nor does the horse react in any way."
The horses are asked to perform for a maximum of eight seconds a couple of times a year, Campin said, and every horse is inspected by independent vets after each ride.
"They do physical reports on all the animals that are used in rodeo and we never have any problems. They just continually come up clean, clean, clean."
But Dunn said the sport is based on a technique that has no place in modern New Zealand.
"Rodeo needs a review. It has been banned in the UK and Canada and Australia is looking at their laws and has already banned some events.
"Here in New Zealand 60,000 people signed a petition saying they wanted a total ban.
"We have to ask ourselves do we really want it in our culture. I think it's time to let it go."