The committee found not only that he had given the banned substance, tranexamic acid, which is used to prevent bleeding, but that he subsequently tried to conceal his actions.
Main, a partner in the O'Gorman, Slater, Main & Partners veterinary practice in Newbury, and former lead veterinary surgeon to racehorse trainer Nicky Henderson, faced four charges of serious professional misconduct concerning his treatment of Moonlit Path, a six-year-old mare.
Three of the charges related to Main breaching British Horseracing Authority rules by injecting Moonlit Path with the substance on the day she was due to race.
The fourth charge related to his dishonest concealment of this treatment in his practice clinical records. Henderson had himself faced a British Horseracing Authority inquiry into this case in 2009 and was subsequently sanctioned.
The committee heard that on February 18, 2009, Henderson's yard requested a veterinary surgeon to attend to Moonlit Path to administer an injection of dycenene the following morning.
The injection was requested as the mare was prone to exercise-induced pulmonary haemorrhage.
Main attended on the morning of February 19 and injected the horse with intravenous tranexamic acid. Moonlit Path raced at Huntingdon later that day, along with the eventual winner, and favourite, Ravello Bay - another horse trained by Henderson.
Moonlit Path finished sixth and a urine sample taken from her after the race tested positive for tranexamic acid.
Of the four charges, Main admitted injecting Moonlit Path with tranexamic acid on the day she was due to race when he knew this breached racing rules prohibiting any substance other than the horse's usual feed and water being given on race day.
However, Main denied knowing that, if tested, a horse would test positive for the substance (thereby imposing a strict liability on the trainer); he denied administering a banned substance to a horse with intent to affect that horse's racing performance; and, he denied dishonestly concealing the injection by omitting it from his clinical records and referring to it as a "pre-race check".
The Committee heard and carefully considered evidence from Henderson and his employees, from investigating officers with the racing authority, and its director of equine science and welfare, from an expert equine physiologist and from Main himself.
In its findings, the committee said it was "unimpressed by Mr Henderson's evidence and surprised by his apparent lack of knowledge of the rules of racing".
While the committee accepted Main believed at the time that Moonlit Path would not test positive for the substance, it considered he failed to fully inform himself of the medicinal product he was using; especially so as tranexamic acid does not possess a marketing authorisation as a veterinary medicinal product.
In so doing, he did not meet his professional obligation to provide Henderson with the information and advice he needed.
The committee concluded that tranexamic acid was a prohibited substance and, whilst accepting Main's concern had solely been for Moonlit Path's welfare, he had actually breached racing rules by affecting her performance through administering such a substance.
Finally, the committee found that Mr Main had deliberately concealed the tranexamic acid injection by describing it in his notes as a "pre-race check" - a protocol developed over several years between the practice and Henderson.
Such inaccurate clinical records were in breach of the college's Guide to Professional Conduct and led the committee to conclude he had acted dishonestly.
The committee also found Main "did not act with candour" by claiming to have administered the substance the day before the race.
On questioning by the legal assessor, however, he admitted that he had known that Moonlit Path was racing the same day that he administered the injection.
Professor Sheila Crispin, who chaired the committee, said: "[We] regard it as wholly unacceptable practice that a veterinary surgeon should be party to serious breaches of rules of another regulatory body in the field of animal welfare ... and which go to the very integrity of racing.
"Whilst the findings relate to a single incident, [we] are satisfied that Mr Main's actions amounted to pre-meditated misconduct ... It is highly relevant that Mr Main held positions of responsibility within the racing industry where he was required to uphold the rules and standards of the profession," she added.
Noting Main's "long and hitherto unblemished career as a highly respected equine veterinary surgeon", the committee accepted Main's evidence that the reason for the administration of tranexamic acid was solely his concern about the welfare of the horse.
Nevertheless, it found his evidence was "evasive, lacking in candour and on some aspects of the case his evidence was untrue".
Crispin concluded: " ... proven dishonesty has been held to come at the top end of the spectrum of gravity of disgraceful conduct in a professional respect ... Having considered carefully all the mitigation put forward on Mr Main's behalf, [we] have concluded that Mr Main's behaviour was wholly unacceptable and so serious that removal of his name from the Register is required."
Main has 28 days in which he can appeal the decision to the Privy Council.