Jockey Racheal Kneller has retired as symptoms which cause the failure of concussion tests required for race-riding persist.
Kneller, who celebrated 47 winners during her time in the saddle, continues to battle the effects of head trauma she suffered in 2020.
The condition would have to improve for the rider to make another comeback, after she previously retired in 2015 due to a lack of opportunities.
Kneller said: "I'm devastated to make this decision, but I won't be returning to a racecourse.
"The symptoms causing me to fail a concussion test needed for racing, have sadly not improved.
"My specialist said I won't race this year, with no certainty that I will have made any further improvements next year either.
"I need to accept that the effects of my head trauma in 2020 may well be permanent now.
"I am totally gutted, but I fell extremely lucky that it wasn't worse.
"I can still ride horses, which is a huge relief. Horses are my life and have been since I could walk."
One of Kneller's most memorable moments on the racecourse came in 2019, when she answered a Twitter plea for a jockey to ride over hurdles.
It was an unusual opportunity, as the race was restricted to those who would normally compete on the Flat.
She won aboard Ruacana, a horse she still rides in retirement at her stables, along with multiple Grade 1 winner Yorkhill.
“I said I ought to go jumping – I had a McDonald’s on the way here and these weights are much better!” she joked in an interview with Sky Sports Racing.
Jockeys carry more weight in races over obstacles, which allowed Kneller the calorific pre-race treat.
Over the years, she overcame a number of serious injuries, including two fractured vertebrae from a 2013 fall.
Throughout 2019 Kneller took 36 rides on the racecourse, but had only competed once since.
