Noel Fehily will be out of action for an as yet unknown period after having keyhole surgery to remove his appendix.
Fehily rode on Friday but gave up his mounts at Kempton on Saturday because of stomach pains, and was subsequently rushed to hospital.
His wife Natasha told www.gloucestershirelive.co.uk: "It all came as quite a shock He rode at Huntingdon on Friday and had a pain in his stomach. On Saturday it got worse and they rushed him into hospital.
"He had an emergency operation to remove his appendix. He's feeling a bit better today - he just has a high temperature at the moment. He's on the way to recovery."
His agent Chris Broad refused to put a time scale on Fehily's return.
"The main thing is for Noel to make a full recovery," said Broad. "Obviously it's a shame to have one of my top jockeys out, and at the moment we don't really know how long he will be sidelined for.
"I'm told the repair time is quicker through keyhole surgery - hopefully he'll be better soon."