Wiltshire event rider Polly Williamson, 41, is in an induced coma in Frenchay Hospital, Bristol after a fall on Thursday.
The four-star rider, who is a former young rider European champion, broke three vertebrae and suffered a serious head injury when her horse spooked during high winds and fell onto her.
Friend of the family Angela Tucker said the doctors are waiting for fluid and bruising to her head to subside.
“The doctors are not concerned about the broken vertebrae but just don’t know [the extent of her head injuries] at the moment,” said Mrs Tucker.
“She might be absolutely fine – we just have to wait and see.”
Polly won six European gold medals when she was in young rider teams, taking individual and team gold in 1987, 1988 and 1990.