The doping test was done on 19 August, at the location where Kieren Fallon had ridden Myboycharlie, and the results of his B sample are now being waited for too.
The news was published just hours after Kieren Fallon and five other suspects were acquitted of race-fixing charges, however, his lawyer Christopher Stewart Moore claimed: "We are looking into the matter as parts of it are curious."
In December last year, Kieren Fallon received a six-month ban after he was discovered to have a metabolite of a prohibited substance in him only five months earlier at Chantilly in France.
