The 73-year-old daughter of Queen Elizabeth II was walking within her Gatcombe Park estate, about 170 kilometres west of London, when an incident occurred.
Catherine, the Princess of Wales, has made her long-awaited return to the public eye at the Trooping the Colour parade for her father-in-law the King's birthday.
The monarch, along with wife Queen Camilla, will visit a cancer treatment centre in London on Tuesday, to speak with others patients and medical specialists.
The monarch stressed the importance of friendship in a pre-recorded message delivered to a traditional pre-Easter church service, which the monarch skipped as he continues to undergo cancer treatment.
King Charles III has spoken for the first time since his cancer diagnosis, releasing a statement to give thanks for the many messages of support he has received.
King Charles III has been diagnosed with cancer just days after hospital treatment for a prostate condition. Buckingham Palace revealed the news in a statement, with UK papers on Tuesday morning splashing the news on the front pages.
Details of royal health are always a tricky issue in the UK, because members of the monarchy are private individuals but also, in a sense, public property.
King Charles III reflected his coronation theme of public service Monday in a Christmas message that he connected to the health of the planet and wars that are raging.
Sarah Ferguson joined the British royal family's walk to church in Sandringham on Christmas morning - a tradition she hasn't taken part in for over 30 years.