The King and Queen each fed a polo mint to the champion racehorse Stradivarius on a visit to the National Stud in Newmarket, Suffolk.
Charles, 76, held out the treat on his right palm for the stallion to take, then stroked the horse on the head.
Camilla, 78, also gave the horse a mint then petted it as the animal loudly crunched on it.
The King said afterwards: “At least he didn’t bite.”
His consort said “keep away from their teeth”, adding: “Now he’s looking for more polos.”
Charles and Camilla were shown four resident stallions on their visit to the National Stud, with each individually paraded before them.
The last of the four was Stradivarius, who has career earnings in excess of £3.4 million and 18 Group wins – more than any other European horse.
The King and Queen, who arrived by helicopter, also spoke to people involved in the horseracing industry during Tuesday’s visit.
Charles shovelled soil into holes beside two already-planted field maple trees and Camilla then watered them from a watering can, before a round of applause, and they left the National Stud in a dark blue BMW car.
