No charges are to be brought against trainers interviewed during a British Horseracing Authority investigation into the use of the veterinary product Sungate.

Sungate contains stanozolol, an anabolic steroid and therefore a prohibited substance under the Rules of Racing.

The BHA spoke to a number of trainers as the treatment was advised by a veterinary practice which all had in common.

The investigation identified that 43 horses from nine trainers had been treated with Sungate since early 2010.

However, all had been correctly entered into the relevant medical records and had been administered by veterinary surgeons and on veterinary advice.

None of the horses produced positive samples, therefore the BHA concluded there were no grounds for charges to be brought.

Newmarket-based trainer Gerard Butler went public over the issue of Sungate in the wake of the Mahmood Al Zarooni scandal, which saw the latter disqualified for eight years after being found guilty of administering anabolic steroids to 15 horses in his care at a BHA hearing on 25 April.

The BHA has been keen to point out that although Sungate contains stanozolol, it is in fact used to treat joints which makes it different to an intramuscular anabolic steroid product, which would have a much higher concentration of anabolic agent.

The BHA said it became aware of the situation following a visit to Butler's yard in February as part of its testing in training programme, from which nine tested positive for stanozolol.

On investigation, it became apparent to the BHA that a veterinary practice, which had imported the drug legally from Italy, was prescribing Sungate and recommended it for horses in training.

After meeting with the vets, the BHA said it was clear Butler was not the only trainer to have used the treatment and the authority met with 38 trainers who used the same vets.

Butler does face charges as he admitted to administering the drug himself in some cases and is not a qualified vet. The date of the hearing has still to be announced.

"We have concluded that there would no reasonable prospect of a disciplinary panel" - Adam Brickell

Adam Brickell, director of integrity, legal and risk for the BHA, said: "Having carefully considered our options under the rules, including taking legal advice and reviewing previous cases, we have concluded that there would no reasonable prospect of a disciplinary panel finding that these trainers have breached the Rules of Racing.

"Under the current Rules of Racing, in the absence of any positive samples, charges could only be brought in cases such as this if there is evidence that the trainer concerned has acted in a manner prejudicial to the integrity, proper conduct, or good reputation of the sport. In these cases there was no such evidence.

"This is because the nine trainers in question only allowed their horses to be administered with the product on the advice of - and by - veterinary surgeons to treat orthopedic conditions.

"Following the completion of this investigation, and the ongoing disciplinary proceedings involving Gerard Butler, consideration will be given as to whether the current rules provide sufficient and appropriate protection against the type of scenario highlighted in this case.

"In addition, while acknowledging that veterinary surgeons are not currently accountable to the BHA, we will consider how we can reduce the risk of incidents such as this happening again.

"The charges brought against Gerard Butler are based on a different set of facts and circumstances to those which were identified during this investigation. A date for this hearing will be announced in due course.

"Meanwhile, all licensed trainers are reminded that if a prohibited substance is found to be present in the system of any horse under their care or control, that would constitute a breach of the Rules of Racing.

"They are also reminded that it is their responsibility as licensed trainers to be familiar with the rules that govern which substances can and cannot be given to horses under their care and control.

"Due to the number of individuals and horses involved, and the volume of records reviewed, the process to ascertain the extent to which this product has been used has necessarily been a lengthy one.

"However, we acknowledge that the cooperation of the trainers in this investigation has made the process less difficult than it might have been."

Jenny Hall, interim chief veterinary officer for the BHA, said: "It is important to note that the product at the centre of this investigation is a treatment designed to be injected into a horse's joints, and is very different to that which might be used in an intramuscular anabolic steroid product.

"The recommended dose of Sungate varies according to the size of the joint to be treated, but a typical intra-muscular injectable anabolic steroid product has around 10 times the concentration of anabolic agent compared to Sungate.

"A recommended dosage would generally contain around fifty times the volume of anabolic agent administered in one Sungate treatment.

"In addition, it follows that when a veterinary product has been used to treat an orthopedic condition there is a recovery period associated with the treatment before a horse can return to the racecourse.

"The clinical histories of the horses in question confirmed that in each case where Sungate had been administered by veterinary surgeons, it had indeed been done so to treat an orthopedic condition.

"However, it remains a matter of serious concern that a veterinary practice recommended and administered a product containing anabolic steroids, which are prohibited substances under the Rules of Racing, to these horses."