Elmer Bandit and Mary Anna Wood out on a ride last year.
Elmer, whose competitive trail-riding tally of 20,780 miles is a US national record, died early on Sunday evening.
Elmer had gone down in his pasture, which he shared with a dozen or so other horses in Independence, Missouri, and had been unable to get up.
Owner Mary Anna Wood recounted to Horsetalk the efforts made to get him on his feet and her final decision, around 6.30pm, to euthanize the horse that she had owned all his life.
His demise was unexpected, with Mary Anna revealing she would have ridden Elmer only the day before had the weather not been so cold.
She had last ridden him on February 6. They were booked for a dressage lesson but their teacher was unable to make it. Mary Anna and Elmer did their own thing. "It was a fun hour we rode," she recalls.
Elmer's body was carried by flatbed truck for three hours to Kansas State University on Monday (yesterday, NZ time), where a veterinary pathologist carried out a three-hour examination, watched by Mary Anna and a companion.
The necropsy had been organised by veterinarian Marsha Hayes, who writes for Thehorse.com.
Mary Anna said the university had been interested in what they could learn from a horse of Elmer's age who had remained so athletic.
She said she was pleased that Hayes had organised the procedure, and it had answered several questions she had about Elmer's health.
"All his organs looked good," she said.
The pathologist found a little scarring at the tip of one lung.
Elmer had suffered a choking problem on and off for most of his life, but an examination of his oesophagus revealed no problems.
The pathologist found a small 2.5cm growth on his caecum (the first portion of the large intestine), which was blood-filled.
They checked out his stifles. "That seemed to be where he had been having his trouble.
"On both of his tibia, on the joint surfaces, there was some evidence of erosion of the cartilage."
His stomach had no signs of ulcers, despite having a number of the risk factors, which included twice-daily meals and the fact that he travelled and competed. There was, she said, only one small area of erosion on the stomach wall, but only affecting the outer-most cells.
Of his remaining teeth, only his incisors still met. However, he still had enough teeth to take care of one of his favourite foods, apples.
Mary Anna said the pathologist would be preparing a report of his findings.
The university would arrange the cremation of Elmer's body.
All efforts to get Elmer standing on the day of his death had failed, and hypothermia likely played a part in the end.
Owner Mary Anna Wood recounted her 38-year-old horse's final day, saying she had arranged for a friend to give Elmer his Sunday-morning feed because of a shift change at work and her wish to attend a neighbour's birthday party.
At 6.30am the friend called her to say Elmer had not got on his feet to have his breakfast.
It was not unusual for Elmer to have a long lie down, but by 9.30am he had still not risen.
Mary Anna was down at the pasture by noon. Elmer wanted to get up but couldn't manage it.
Elmer Bandit with Mary Anna Wood during a trail ride in October, 2006, in the Kansas Flint Hills.
© Olivia Huddleson
"He just could not get his hind legs under him," she said.
The owner of the property was later called and came down with a Bobcat digger.
However, the cold was starting to take its toll and Elmer's body temperature was dropping.
"It wasn't even up to freezing [point]," Mary Anna said. The wind was bitter and snow flurries had moved in.
Strops were placed around Elmer and he was lifted, but by that stage he was unable to stand on his feet.
Mary Anna said even if they had managed to get him standing, it inevitably would have happened again.
"He had been down for at least 12 hours when we put him down," she said.
It had only been in the last hour that he had stopped trying.
She made the decision to euthanize him and Elmer passed away peacefully around 6.30pm. "I have no regrets," she said.
Elmer completed two competitive trail rides last season to add to his record tally, with Mary Anna completing five other rides on other horses.
"I am not really reward-orientated," she said. "But I am really pleased that Elmer made the Hall of Fame, or when he was high-point half-Arabian, or took regional honours."
His last competitive ride was last September, in Iowa. "We had fun ... He enjoyed every step of it."
Mary Anna continued to take regular dressage lessons on Elmer after that, including one week when they had them four days in a row.
His death was unexpected, and he was playing happily when she turned him out after his supper on Saturday afternoon.
"If his joints hadn't given out, we could still be going today," she said.