Madonna had been riding a new horse. Her children, Rocco, five, and Lourdes, eight, were at the estate but were not with their mother when the accident happened late in the afternoon, according to Liz Rosenberg, Madonna's publicist.
"The whole family was out in the country, celebrating her birthday," Ms Rosenberg said.
Madonna's husband, the film director Guy Ritchie, took Madonna to Salisbury District Hospital, where she was treated. She was released from hospital late last night.
Madonna has reinvented herself since meeting Ritchie, director of Lock Stock and Two Smoking Barrels. She is pictured as a lady of the manor in Vogue this month, feeding chickens with himin the style of a latter-day Grace Kelly. The photographs reflect her switch to country life, taking riding lessons and adopting the 1,200-acre estate as a country residence.
The singer told the Sunday Mirror recently: "The last thing I thought I'd do is marry a laddish, shooting, pub-going nature lover. And the last thing he thought he was going to do was marry a cheeky girl from the Midwest who doesn't take 'no' for an answer. But now I see England as my home. I love England and want to be here, and not in America."
Ashcombe House is in Tollard Royal on the Wiltshire-Dorset border. Recently Madonna won a legal case to keep ramblers off most of the £9m estate, and she is building a recording studio in the grounds.
Stag Riding Stables, near Richmond Park in south-west London, where Madonna recently had lessons and borrowed two horses, said they were not involved in the accident.
The proprietor, Julie Gatt, said the singer had returned the horses after a few days, after borrowing them in early July.
"She had a few riding lessons here with us," Ms Gatt said.
"She borrowed a couple of horses but she's not been in since then. She's a lovely lady and we're very sorry to hear about her accident."Reuse content