As King went to leave the yard to continue the conversation something spooked the horse.
"It reared up, kicked and then repeatedly stomped upon Mr King who had ended up on the ground."
Witnesses described the attack as "nasty and vicious" and said it appeared the horse was deliberately attacking King, which was something they had never seen before.
King was breathing but unresponsive after the attack, an ambulance was called and he was later flown to Waikato Hospital by helicopter.
A scan showed King suffered bruising to the brain and after being assessed by a neurosurgeon his injuries were deemed unsurvivable.
He suffered abrasions to his head, chest, back, shoulders and arms, a post-mortem examination identified.
A police investigation found there were no circumstances of a criminal nature in King's death while WorkSafe inquiries concluded he may have breached the Health and Safety at Work Act which required self-employed people to ensure their own health and safety at work.
Coroner Wrigley found King was affected by alcohol, due to the high level found in his system, and potentially cannabis at the time of the attack but wasn't satisfied there was any evidence his handling of the horse was impaired or that his co-ordination was adversely affected.
"So, while Mr King's use of alcohol and cannabis before engaging in the dangerous task of breaking in a horse is highly inadvisable, I am not satisfied on the balance of probabilities that it contributed to his death."
While Coroner Wrigley concluded a helmet wouldn't have prevented the attack, it could have changed the outcome.
"I consider it is more likely than not that if Mr King was wearing a helmet at the time he was attacked by the horse this could have mitigated the severity of his head injury, and in doing so saved his life."
She made recommendations to potentially prevent further deaths in similar circumstances including all people handling a horse being broken in wear a helmet whether they were mounted or unmounted.
It was also advocated WorkSafe review and supplement its Good Practice Guidelines for riding horses on farms, within a year, to ensure the risks identified in King's death were adequately addressed.