The 15-year-old from Shetland had travelled to Glasgow to compete in this weekend’s British para swimming championship in Glasgow’s Tollcross International Swimming Centre, where the Paralympic team will be chosen.
As a teenager Davies has to undergo regular tests to ensure her disability is severe enough to qualify in the para events.
In a statement Scottish Swimming said: “In line with IPC classification process, Erraid Davies of Delting Dolphins in Shetland has been deemed ineligible to compete in the forthcoming British para Swimming International Meet.”
Under the standard protocol, Davies will be assessed again over the summer, probably in June.
A Scottish Swimming spokeswoman said: “While Erraid and her family are extremely upset and disappointed with the outcome, they welcome the opportunity of a second review and both Scottish Swimming and British Swimming are supporting them at this time.”
Davies has a disorder known as Perthes Disease in her left hip. She shot into the limelight in the 2014 Commonwealth Games in Glasgow when she won a bronze medal in the 100m breaststroke at the age of 13, the youngest ever athlete to compete in the Games.
Her father David said: “In one way we are very happy [that she has been classified as able-bodied], but we know the pain that Erraid suffers quite regularly and she has difficulty walking any long distance.
“It’s a really distressing time for Erraid because since the Commonwealth Games she has been under extra pressure to get a qualifying time for Rio and now she may have lost that opportunity.”
Shetland, where Davies moved when she was just four years old and barely able to walk, has taken the young swimmer to its heart ever since her Commonwealth Games success.
As well as garnering huge national media attention, she was shortlisted for a Young Scots Award.
She has been fundraising hard to help her attend training events for the Paralympics.
Only this week airline Loganair announced they were sponsoring her flights to and from Shetland with her mother, the first of which was to this weekend’s event in Glasgow.
Loganair director Roy Bogle said: “Erraid was rightly one of Scotland’s biggest success stories during what was a fabulous Commonwealth Games in Glasgow in 2014, and we are happy to make what is a small contribution to supporting her enormous talent.”