Racecourse vets were yesterday warned to be extra vigilant about shielding spectators from their work after horrified racegoers watched a surgeon saw the leg off a dead horse.

The Jockey Club said it had launched an investigation after veterinary surgeon Keith Mason began sawing up Midyan Blue in a horsebox after the horse had fallen fatally in the 4.30 race at Musselburgh on Monday, unaware that he could be seen by people in the hospitality area.

Public relations officer John Maxse said no action would be taken against Mason, a Jockey Club vet described as one of the most conscientious members of his profession, but added that stringent guidelines had been issued following the incident.

He said: "It is not acceptable for any member of the public to have to witness such an incident. It was a mistake by the vet, who was unaware that anyone could see him."