When Dutch equestrian Adelinde Cornelissen went to the barn after a few days in Rio for the 2016 Summer Olympics, she discovered things were not right with her horse, Parzival. She noticed the right side of her horse's head was swollen and he had been kicking the walls in his stall. Cornelissen checked and saw Parzival was running a fever, so she brought in several vets.

"They concluded he was bitten by an insect or spider or some sort of animal which produces toxics," she wrote on Facebook.

Parzival, who won individual silver and team bronze at London 2012, was given fluids, and X-rays were taken of his jaw. Gradually, his temperature dropped and the swelling began to slowly subside, Cornelissen wrote.

"I slept at the stables, checking up on Parzi every hour ... I was not going to leave him alone! "

Parzival was eating and drinking normally, looked fit and the swelling was nearly back to normal. Several vets and the team coach all gave the horse the green light to compete. Cornelissen didn't want to disappoint her team and, because they had no spare horses, she decided to go ahead and compete.

She took him into the arena, but he didn't feel very powerful.

Adelinde Cornelissen of Netherlands competes with Parzival in the Olympics Adelinde Cornelissen of Netherlands competes with Parzival during the dressage individual Grand Prix event on Day 5 of the Rio 2016 Olympic Games before pulling him from the competition. (Photo: Sean M. Haffey/Getty Images)

"When I entered I already felt he was giving his utmost and being the fighter he is, he never gives up... But in order to protect him, I gave up," Cornelissen wrote. "My buddy, my friend, the horse that has given everything for me his whole life does not deserve this.... So I saluted and left the arena."

Mary Jo DiLonardo Mary Jo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.