The 95-year-old monarch's horse, Kincardine, won the Federation of Bloodstock Agents Maiden Hurdle at Newbury racecourse.
WATCH: The Queen tests positive for COVID-19
Trainer Nicky Henderson told Racing TV: "We were all sad to hear Her Majesty has Covid – I don't know if that’s Covid medicine but I hope it is."
Shortly after the race, Newbury Racecourse also tweeted: "We hope this cheers you up Your Majesty! Kincardine wins The Federation Of Bloodstock Agents Maiden Hurdle! Get well soon! [heart and horse emojis]."
The Queen has had an interest in horses from an early age and has owned many thoroughbred horses for use in racing. Her Majesty also hosts the Royal Windsor Horse Show in the grounds of Windsor Park.
The Queen at Ascot in October 2021
Buckingham Palace confirmed on Sunday that the Queen is experiencing mild cold-like symptoms but expects to continue light duties at Windsor Castle over the coming week.
It comes after a number of cases were diagnosed in the team at the monarch's Berkshire residence.
It's understood that the Queen was well enough to sign off a congratulatory message to Team GB's curling medallists at the Beijing 2022 Winter Olympic Games, writing: "I send my warmest congratulations to the Team GB Women's Curling team on your outstanding performance in winning the Gold Medal at the Beijing 2022 Olympic Winter Games, following the Silver Medal achieved by the Men's Curling team yesterday.
"I know that your local communities and people throughout the United Kingdom will join me in sending our good wishes to you, your coaches and the friends and family who have supported you in your great success. Elizabeth R."
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