Trainer Kim Bailey says his yard are "guilty of bad stable management" after being found in breach of rules on administering a substance on the day of a race.
Bailey's Subway Surf - part-owned by TV personality Carol Vorderman - was withdrawn by stewards at Ludlow in March after being found with a substance around her mouth. A subsequent search uncovered "two unlabelled syringes containing an unidentifiable brown liquid", one of which had been used.
On Thursday, Bailey wrote publically to explain that the mystery substance was a herbal paste, called Pulmon Pro, and was administered to prevent the horse breaking a blood vessel.
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In the case, which had been fast-tracked by the British Horseracing Authority's (BHA) judicial panel, Bailey received a £1,000 fine.
The BHA report added that the substance was confiscated and sent for testing, which later revealed findings for "multiple prohibited substances", however Subway Surf's tests came back clear and therefore no anti-doping violation was committed.
Writing in his blog, Bailey explained: "When she [Subway Surf] arrived at the races the vet saw a residue of a paste around her mouth that she was given that morning.
"The paste is a herbal paste called Pulmon Pro which is something she is given on a daily basis in the belief that it would help her stop breaking a blood vessel.
"This is administered orally and at no stage was she injected.
"My second travelling head girl unfortunately put the wrong bucket into the horsebox containing the oral syringes that we administer the Pulmon Pro with.
"On testing these syringes were found to contain tiny traces of other substances that are used in all racehorse stables around the country.
"We have to hold our hands up to say that we are guilty of bad stable management as we should have not administered anything after midnight on race day."
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In a separate case, fellow trainer Oliver Greenall also received a £1,000 fine for administering a substance on a raceday.
Stewards at Doncaster on March 18 found Greenall's Furius De Ciergues with a "sticky green substance" by the mouth and "dried blood" on a neck vein.
A member of Greenall's staff reported that the substance had been given to the horse the previous day, although this was viewed by a veterinary officer as "unlikely".
Furius De Ciergues was withdrawn and the sample was returned as negative for any banned substances.