Karen Kenny has suffered a "small subdural haemorrhage" after the jockey fell at Tramore on Saturday evening.
The 7lb claimer was knocked unconscious when she was unshipped from Our Pearl two furlongs from home in the opening mile-and-a-half maiden.
Kenny was airlifted to Cork University Hospital and underwent a brain scan.
Dr Adrian McGoldrick, senior medical officer for the Irish Turf Club, said: "Karen Kenny has suffered a small traumatic subdural haemorrhage and is currently being assessed.
"She was unconscious for about three minutes but she was semi-conscious when she left.
"She was able to respond to us and she knew she was in Tramore."
Dr McGoldrick continued: "She is much more stable now than she was when leaving here (Tramore).
"She will be observed overnight."