A second Newmarket trainer faces a British Horseracing Authority probe over using steroids on horses just days after the Godolphin doping scandal rocked the sport.
Godolphin trainer Mahmood Al Zarooni was given an eight-year ban on Thursday for using prohibited steroids on 11 horses, who tested positive when BHA officials made an unannounced visit to the stable owned by Sheikh Mohammed
And on Monday trainer Gerard Butler told the Independent newspaper that several of his horses had anabolic steroid treatment for injured joints.
Butler says more than 100 Newmarket-based horses may have been given the same banned drug, but he claimed he had been assured by vets that the substance did not breach rules.
Butler included the injections in his official medical records which were seen and returned by the BHA without comment.
Anabolic steroids are banned in the UK, although allowed out of competition in countries including Australia, Dubai and the United States.
"It did not cross my mind that there could be any problem with this medication," Butler told the Independent. "And, judging from the fact that the BHA said nothing about it when they saw my medical book, it does not seem to have crossed their minds, either.
"Little Black Book ran on 4 August, and won a couple of weeks later, so they would have known he was clearly in training at the time.
"In the medical book, I signed that I had authorised use of the drug, and my vet had countersigned for its administration.
"Sungate (the steroid treatment for injured joints), had for some time been widely used in their practice, with very beneficial results for joint injuries."
Butler, 47, has trained a number of top horses including Elusive City and Compton Admiral, while he has also had success in the United States.
In 2011, he saddled Pachattack to finish third in the Ladies' Classic at the Breeders' Cup, the most prestigious fillies' race in America.
After admitting self-administering the same treatment to other horses, Butler could now face a ban and he conceded he had made an error of judgement.
"The fact I didn't put that on the record shows that I knew it was wrong to diagnose and medicate those horses myself," he said.
"It was an unpardonable misjudgement, purely to cut corners in what is a very expensive treatment. But I have been totally candid throughout with the BHA, and it was I who told them that I had treated four colts in December and January.
"I'm not trying to defend myself, just to explain what happened. And I must emphasise that I was advised in good faith by my vets."