When the Maryland Racing Commission indicated that it is about to ban the use of all drugs at the state's tracks, horsemen started moaning immediately.

Trainers and owners have been citing the practical benefits of Butazolidin and Lasix, and they will carry their arguments to the commission's hearing in Baltimore next Thursday. They will say:

In an era when year-round racing places great physical stress on thoroughbreds, Butazolidin is neccessary to keep them running. The average owner cannot afford the expense of giving a horse a lengthy vacation to recuperate from his ills.

Using Bute is a far more sensible and humane practice than the most common alternative, "tapping" a horse to remove fluid from his knees or ankles. Medication can help an animal be productive for years; tapping joints will wrecking him quickly.

Bute and Lasix are legitimate medications, not stimulants. They don't alter or distort a horse's form; they merely let him run to his potential.

These arguments in favor of drugs are sound and accurate. There is only one thing wrong with them. They are the same arguments that horsemen and veterinarians used in 1974 when they campaigned successfully to have Butazolidin and Lasix legalized in the first place. That legalization, Maryland and other states, started a wave of drug abuse unprecendented in the history of the sport.

Nothing was more flagrant than the misuse of Lasix. The drug was introduced to race tracks because it helped the small percentage of thoroughbreds who are bleeders. It would be hard to object to this use of the medication; no one likes the sight of a horse being pulled up in midrace with blood steaming from his nostrils.

No more than one horse in 20 is a bleeder. But yesterday at Laurel, 54 of the 82 horses on the program had been given Lasix. (In addition, almost every starter had Bute.) "All the horses are using these drugs," racing commission Chairman Robert Banning concluded, "whether they need them or not."

The reason is obvious to anybody who knows the training profession: it is a competitive, cut-throat game, and nobody wants to surrender the slightest edge to anybody else. And many want to take an edge. The proliferation of legal drugs has surely created a climate in which horsemen and vets will almost unhesitatingly use illegal substances if they can get away with it.

Lasix can help them get away with it, by diluting the drugs in a horse's system so they are practically untraceable. It can't be mere coincidence that "controlled medication" programs have been accompanied by the appearance of a multitude of narcotics like Sublimaze, Stadol and Methodone.

Some critics objected to this wanton use of drugs because it was inhumane to the horses. But it was even more inhumane to the bettors. Drugs, legal and illegal, struck at the very foundation of the sport: the fact that a bettor can apply his intelligence and powers of observation, handicap a winner and make money. Without that presumption, horse tracks might as well be converted into bingo parlors.

Good handicappers can learn to evaluate almost any factor -- even larceny -- but the legalization of drugs introduced an element into the game with which outsiders could not possibly cope.

Three weeks ago, a New York trainer sent a horse to Maryland from New York, where he had finished out of the money seven straight times. In New York, no drugs are permitted; now this horse was getting Bute and Lasix for the first time. A bettor could only guess what the affect of these medications would be, until the horse woke up and won at 15 to 1.

That was a relatively benign illustration of the way trainers can use drugs to their own benefit and to the detriment of the public.

With such a powerful tool in their hands, trainers have irresistible opportunities to control and manipulate the performance of their horses. And many of them have surely been taking advantage of these opportunities.

It is no wonder that horsemen are going to argue passionately before the racing commission that Butazolidin and Lasix should remain legal. But the horsemen have had their chance. They got their "controlled medication" program five years ago, they abused it flagrantly and turned it into a shambles, and now they deserve to suffer the consequences.