He said the woman and her husband, both experienced farmers, were loading the second storey of a stock truck when the accident happened.
"The animal has jumped off the loading ramp and landed on top of her. She would have been standing where anyone loading a stock truck would have been standing.
"It's just a freak accident," Mr Watts said.
He said there had been the odd case of people being crushed by cows but this case was quite unusual.
He believed the woman also had a gash to her head and may have fractured her eye socket.
"I would say she's not out of the woods yet," Mr Watts said.
Te Puke St John operations team manager Simon Campbell confirmed the accident was caused when a cow jumped over a rail on a truck they were loading and landed on top of the woman.
The woman sustained spinal injuries as well as leg and arm injuries.
