Horsemen turned out in force at Bowie yesterday to argue the merits of the controversial drug Lasix before a study panel of the Maryland State Racing Commission.

Trainers Grover Delp and King T. Leatherbury, one-two in the standings at Bowie, said that Lasix, a diuretic, was beneficial to the many horses will breathing problems.

Donald Levinson, former state commissioner, again chaired the meeting, the fourth in the current study called to determine the efficacy of the medication program in use at Maryland tracks.

The only opposition to the use of Lasix came from J. William Boniface, Maryland Horse Breeders Association president, who stated that his organization was opposed to the entire medication program that includes Butazolidin.

Testimony by Thomas Lomangino, chief chemist, was made to the effect that Lasix, a dilutant, could not mask another, more potent, drug. The chemist also testified that there is no reliable testing for the narcotic Sublimaze at this time.

Dr. Davie L. Paice, state veterinarian, expressed the view that although Lasix does have some questionable effects upon horses, the drug can be a most useful aid when used property.

Snowden Carter, representing the breeders, said there should be improved prerace testing and/or supervision. The statement brought the response from Levinson, "Where are we going to get the money?"

The series of meetings were called by the Maryland State Racing Board after the death of jockey Robert A. Pineda who was killed when his mount Easter Bunny Mine was involved in a spill at Pimlico May 3. Pineda's widow has filed suit, charging that the use of pain-killing drugs were contributing factors in his death.

The board is expected to make a ruling later this month.