Godolphin scandal: Trainers' Federation shocked by doping
The National Trainers' Federation (NTF) says it is stunned that horses from the Godolphin operation have tested positive for anabolic steroids.
Banned substances were discovered in 11 horses trained by Mahmood Al Zarooni, who now faces a disciplinary hearing.
"Like everyone else in the sport, the NTF is shocked at the news," said chief executive Rupert Arnold.
He added that the scandal was in no way symbolic of a wider culture of doping within the sport.
And he expressed the hope that the case would send a "positive message" that would help keep the sport clean.
Godolphin, owned by the Al Maktoum family that rules Dubai, is one of the most successful racing operations on the planet and recently secured its 200th Group One victory.
NTF chief executive Arnold added: "The Godolphin management, for whom Mr Al Zarooni trains, is a byword for the highest levels of professionalism, integrity and sportsmanship.
"News reports so far suggest this case is an aberration and is not indicative of wider use of anabolic steroids in British horseracing.
"We fully endorse the British Horseracing Authority's testing in training regime and all efforts to prevent the use of any prohibited substance to gain an unfair advantage.
"Without wanting to diminish the seriousness of this case, in some ways it is a positive message that the presence of these substances was detected so the sport is kept clean."
The British Horseracing Authority (BHA) said that on 9 April samples were obtained from 45 horses trained by Al Zarooni at Moulton Paddocks Stables in Newmarket and that the Horseracing Forensic Laboratory had detected prohibited substances.
The 11 horses, who together have won more than $2m (£1.31m) in prize money, included unbeaten Certify, who will not be allowed to run in next month's 1,000 Guineas at Newmarket.
Bookmaker Ladbrokes has said it will refund advance bets totalling £200,000 that had been placed on the 11 horses. Alex Donohue of Ladbrokes said: "Given the circumstances we feel it's only fair customers get their money back."
Racehorse trainer James Given said the controversy would bring "huge embarrassment" to Sheikh Mohammed, the head of the Maktoum family and the ruler of Dubai, who oversees the stable and appointed Al Zarooni three years ago.
"Sheikh Mohammed has been very vocal about trying to get the Americans to improve, regarding their reliance on medication," Given told BBC Radio 5 live.
"On the one hand, he's leading the charge there, and then in his own camp, this happens. They will, without doubt, have an investigation in their own camp."
Given said the use of anabolic steroids, which can be administered orally or by injection, could have a dramatic effect on a horse's performance.
"It's not just active while the drug is in the body - and certainly many of these drugs will persist in the body for several months - but it's the effect on the muscle development beyond its natural capacity," he explained.
"The horse can train harder while it's in receipt of the medication, and it also assists with recovery from injury.
"It is, without doubt, a performance-enhancing substance, and an unfair advantage is sought by using these drugs."