Maryland horseplayers have often viewed the state's racing commission as an enemy rather than a defender of the public interest. This assessment was sustained by last week's hearing on the controvesial drug Lasix.

The question of whether to keep Lasix legal is a complex one because even expert scientists don't fully understand it. They do know that Lasix is a diuretic that increases horses' urinary output, affects respiration and blood pressure, and helps some animals who chronically bleed from the nostrils, but the scientists aren't sure how or why the drug works.

In one sense, the Lasix issue is a clear-cut one. It represents a head-on collison between the private interests of trainers and veterinarians and the public.

Almost all trainers favor unrestricted use of the drug, for obvious reasons. Lasix makes their horse run better, sometimes drastically so. And it may conceal the presence of certain illegal narcotics in a horse's system. Racetrack veterinarians naturally support the trainers; they earn their living by administering medications.

Most racing fans however, detest the very existence of these sophisticated drugs. Medications like Lasix threaten the very basis of the sport's appeal: the premise that a bettor can use his intelligence and judgment to pick winners and make money. Although a handicapper can assess speed and class factors, he can only guess at the impact that drugs wil have on horses' performance.

In recent years Maryland racing has degenerated into such a guessing contest. Since John Tammaro became the first trainer in the state to discover Lasix, and started improving some horses by as much as 20 lengths overnight, the game has not been the same.

The Maryland Racing Commission heeded the pleas of trainers and the assurances of veterinarians and approved the unrestricted use of Lasix (along with the painkiller Butazolidin) in 1974. But doubts about the drugs wouldn't go away, and they intensified. In May, a Bute-treated horse broke down at Pimilco and jockey Robert Pineda was killed in the spill.

That tragedy prompted the commission to create a panel, headed by Donald Levinson, that would review the whole drug question. But last week's meeting at Bowie suggested that the whole exercise was little more than window dressing.

There was not much real debate at the meeting, because almost everybody held the same viewpoint. Levinson asked the 15 trainers in attendance if any favored any restrictions on the use of Lasix. Not a hand was raised.

One panel member who is an opponent of Lasix, William Boniface Jr. of the Maryland Horse Breeders Association, said he wasn't invited to the meeting. "I've been outspoken against medication," he said, "and a lot of pressure is coming now to keep the medication going."

With no one to contradict them, and without any racing commissioners willing to ask probing questions, the advocates of Lasix could recite the old litany of lies and half-truths that had persuaded the commission to legalize the drug in the first place.

They testified that Lasix does not "wake up" horses or alter their form - an argument that the results of races in Maryland will not support. The Lasix forces said the drug will not mask the presence of illegal narcotics. This claim has been refuted by a study at the University of Kentucky that concluded that the use of Lasix in conjuction with certain narcotics like morphine "substantially reduces the probability of their detection, given the current state of the art of drug screening."

Nevertheless, it seems the Maryland Racing Commission will accept as fact the self-serving arguments of the trainers and veterinarians who want Lasix and vote to keep use of the drug unrestricted. Like so many regulatory bodies, the commission caters to the wishes of the people it supposedly regulates. In this respect, the commission is one of the few entities in Maryland racing that usually runs true to form. Pearl Necklace, virtually wrapped up the best older filly and more championship for the 4-year-old homebred daughter of Stage Door Johnny out of the Toom Fool mare Dunce Cap II.

Ridden by Jorge Valesquez, Late Bloomer stalked Pearl Necklace for most of the 1 1/4 miles. At the eighth pole she took the lead on the outside.