Liam Treadwell was taken to Wrexham hospital for further assessment after being knocked unconscious in a fall at Bangor.
The Grand National-winning rider was partnering Market Option for his principal employer Venetia Williams in the Stella Artois Supporting Bangor-On-Dee Handicap Chase when the pair came down at the second fence.
Treadwell was knocked out on impact but had regained consciousness and was moving when he was taken away by ambulance.
Clerk of the course Andrew Morris said: "Liam Treadwell was conscious when he was put in the ambulance.
"He was taken to Wrexham Hospital for further assessment as he was knocked unconscious."
As a result of being unconscious Treadwell will face a mandatory spell on the sidelines.
Weighing-room colleague Aidan Coleman told Racing UK: "As far as I know, we've been made aware he's just gone for precautions.
"He was much better when they got him off the track and they were quite happy, but any time you get a knock like that they have to err on the side of caution.
"It was a heavy fall and he's just gone to the local hospital, where hopefully they'll give him the all-clear. He's lucky."