The Princess Royal is “recovering slowly”, her husband has said, after visiting her in hospital where she is being treated for a minor head injury.

Princess Anne, 73, has spent three nights in Southmead Hospital, Bristol, after she sustained a minor head injury and concussion thought to have been caused by a horse at her Gloucestershire estate.

On Wednesday, Vice Admiral Sir Tim Laurence visited her in hospital for two and a half hours, leaving just before 14:00.

When asked whether his wife would leave hospital the same day, he said: “She’ll be out when she’s ready.”

The Princess Royal’s daughter Zara Tindall also visited her mother for more than an hour on Tuesday afternoon.

Buckingham Palace said on Monday that Princess Anne, King Charles III’s sister, was expected to stay in hospital until later this week “as a precautionary measure for observation”.

The Princess Royal is expected to make a full recovery, but she missed the state banquet with the visiting Emperor and Empress of Japan on Tuesday and her trip to Canada this week has been postponed.

She was injured on Sunday evening when she was out walking on her estate and horses were nearby. It is understood the princess has not been able to recall the details of what happened due to her concussion.

Her medical team suggested her head injury is consistent with the type of impact from a horse’s legs or head.

According to the NHS, concussion can be the result of a “temporary injury to the brain caused by a bump, blow or jolt”. It can cause forgetfulness, tiredness and a lack of concentration and can take a couple of weeks before a full recovery.

Princess Anne is the third working royal to temporarily step back from public duties this year because of a health problem.

The King and the Princess of Wales both stepped back from public engagements in the first half of the year after they were both diagnosed with cancer.