Princess Anne, the younger sister of King Charles III, was released from a hospital on Friday, five days after suffering a concussion and other injuries in an accident at her country residence, northeast of Bristol, England.

Anne, 73, was hospitalized on Sunday after the incident, according to Buckingham Palace, which announced her release. Officials have been vague about what happened but have said they believe it involved some kind of impact with horses on the estate, Gatcombe Park. It was not clear whether Anne remembers the incident or whether they were any witnesses to it.

On Monday, the palace said Anne would “make a full and swift recovery” and was being treated at in Southmead Hospital as “a precautionary measure for further observation.” But her husband, Timothy Laurence, visiting her a day later, acknowledged that her recovery, while steady, had been “slow.”

In statement on Friday, Mr. Laurence said, “I would like to extend my warmest thanks to all the team at Southmead Hospital for their care, expertise, and kindness during my wife’s short stay.”

The palace said Anne would return to her public duties based on the recommendation of her doctors, but it offered no timeline. She has postponed a trip to Canada and was not present at a state dinner for Emperor Naruhito of Japan and his wife, Empress Masako, at Buckingham Palace on Tuesday.

The palace’s decision to offer few details about Anne’s condition or prognosis was in keeping with its approach to health matters for other senior members of the royal family, and it pleaded with the news media to let her recover in private. An official said she would undergo standard rehabilitation for a person who has suffered a concussion.

Anne is an accomplished equestrian who competed for Britain in the 1976 Olympic Games in Montreal. The palace said her injuries were consistent with coming into hard contact with the legs or head of a horse.

The sidelining of Anne is another blow to the royal family, which is coping with the illnesses of two of its most visible members, Charles and Catherine, Princess of Wales, both of whom have been diagnosed with cancer.

Anne is viewed as one of the hardest-working senior royals, routinely logging more than 400 officials events a year. Her workload has increased as the family’s ranks have been thinned by the deaths of Queen Elizabeth II and her husband, Prince Philip; the illnesses of Charles and Catherine; and the bitter family rift with Prince Harry and his wife, Meghan, who moved to California.