A trainer has a hundred ways to prevent his horse from winning and they are all pretty simple, ranging from fitting its shoes too tight or giving it a belly-filling bucket of water, but more usually running it on firm ground when it needs soft, on a left-hand track when it prefers to race right-handed, or just letting it take part when it is too fat and unfit to do itself justice.
This is all designed to fool the official handicapper and the betting public about the horse's merit; saving it for a day when it has a lighter weight to carry and the money is down.
For the doper these methods are not possible and a different outcome sought. The doper is aiming either to slow a horse down so that he can back others in the race or, if he is a bookmaker, so that he can take bets on the doped horse without fear.
The prospective doper requires access to the right drugs and access to horses at the right time. The favoured drug of the Nineties, the one used in the Avanti Express and Lively Knight cases and on two horses at Doncaster in 1990, is frighteningly easy to obtain and can be found in every racing stable in the land.This is Acetylpromazine, ACP, a fast-acting mild tranquilliser used to sedate a horse on occasions such as when it is having its coat clipped. It is obtainable only from vets but is so frequently used that it is usually kept in quantity in stables and not necessarily under lock and key.
ACP can be administered by injection but is more commonly given in tablet form. Just like drugs used on humans, its effects vary widely. While one horse might be almost unaffected, another might be out on its feet on the same dose. The dangers of giving ACP to horses that are about to take part in a race, and in the cases of Avanti Express and Lively Knight about to jump fences, are clear.
ACP is at its most effective about an hour after it is administered so the doper must obtain access to the horse at the track. Effectively, that means in the course stables and, after the 1990 cases, security at Britain's 59 tracks was improved greatly. Nevertheless with hundreds of stable staff coming and going the possibilities of a doper slipping through the net are clear.