Vet James Main has been struck off by the Royal College of Veterinary Surgeons (RCVS) after administering a banned substance to a horse belonging to The Queen.

An RCVS disciplinary committee inquiry into Mr Main’s actions, which started on 14 February, finished yesterday evening (Tuesday 22 February).

He was struck off for an indefinite period after being found guilty of “disgraceful conduct”.

At the inquiry Mr Main admitted injecting Moonlit Path, a mare trained by Nicky Henderson, with the banned drug tranexamic acid, which aids blood clotting, on the morning of her racecourse debut, 19 February 2009.

In a random drugs test the horse, which finished sixth at Huntingdon, tested positive. It is illegal to give anything other than food and water to a horse before racing.

But Mr Main said his primary concern was for the horse’s welfare — not to enhance her performance.

Mr Main has 28 days to appeal the decision, during which time he may continue to practice.

“I am deeply shocked and disappointed. The prospect of not being able to earn a living as a vet is a matter of grave concern,” Mr Main said.

“I wish to apologise for this regrettable episode to all those involved. I would like to stress that I sought to act only in the interests of Moonlit Path’s welfare.”

The RCVS panel ruled he had: “acted dishonestly” and found that his “evidence was evasive, lacking in candour and on some aspects of the case his evidence was untrue”.

At the time Mr Henderson was fined £40,000 by the British Horseracing Authorty (BHA) and banned from making entries for three months.

After the incident Mr Main stepped down from the BHA veterinary and counter-analysis committees. He also parted ways with Mr Henderson.

The BHA is now considering further disciplinary proceedings.

Nicky Henderson’s assistants Tom Symonds and Ben Pauling could also be a risk of disciplinary action after admitting knowing the vet had been asked to inject the horse.