The 7-year-old horse had won only one race in his life, at the rock-bottom level of Midwestern racing. Since then, he had been plagued by one infirmity after another, but his trainer kept investing his time and money in an effort to get the horse back to the races.

The animal had been training for a few weeks, but one morning he came back from the track in obvious distress, having bowed a tendon again. He was going to be sidelined many more months. As the trainer stood in front of his barn, surveying the damage, Dr. H--, one of the most famous veterinarians in the United States, drove by.

The trainer waved frantically. "Doc," he said, "look at my horse. Can you do anything for him?" The vet nodded silently, walked to the back of his car, opened his trunk and produced a syringe. Without comment, he administered an injection in the horse's neck.

Thud! The horse crashed to the ground and within seconds was dead. "This horse isn't going to cost you any more money," Dr. H-- told the trainer, and drove away.

The vet who told this story elicited a round of laughs from colleagues who had been attending the national convention of the American Association of Equine Practitioners. But it also reflected the central dilemma of their profession: the frequent clash between the welfare of the animal and the hard realities of the sport.

As an outsider, I have always thought of race track vets as an all-knowing, all-powerful and somewhat sinister bloc that wants to rule the game by wielding its hypodermic needles. But I came away from the convention with a very different impression. Veterinarians feel frustrated, almost impotent as a group, because they often are thwarted from doing what they believe is right for the animal.

Part of their frustration stems from the economics of modern racing, from the fact that it is too costly to give horses adequate rest to recuperate from injuries. As Charles Vail, a vet from Colorado, put it, "Trainers will tell you, 'Do everything that's right for him, Doc, but can you get him ready for a race next Wednesday?' "

But the vets' greatest frustration stems from the ceaseless controversy over legalized medication, from the hostility of the public (and many state racing commissions) toward Butazolidin and Lasix.

There was no debate here about whether Bute and Lasix should be legal. On a couple occasions, I played devil's advocate and suggested that by allowing these drugs in stakes races we may be harming the evolution of the thoroughbred. Do we want a horse like Gate Dancer, who needs Lasix to build a reputation while running so he can go to stud and propagate hundreds of drug-dependent offspring?

Veterinarians wouldn't even entertain the question. They point out that as many as 80 percent of modern thoroughbreds suffer from respiratory problems, and that Lasix is a safe, effective medication for treating those problems. End of discussion.

The members of the AAEP view the use of Bute and Lasix as being so sensible, so humane, that they have trouble comprehending why there is so much resistance to these drugs. Having been invited here to deliver a speech about Lasix and medication policies in general, I had the chance to offer my own theory before a captive audience: the vets themselves are largely responsible.

When racing commissions in Maryland and other states were debating the legalization of Lasix, veterinarians appeared as expert witnesses. They were so determined to win approval of the drug that their testimony was not completely candid.

They assured commissions that Lasix wouldn't affect a horse's form, when every bettor knew otherwise. They didn't insist that a Lasix program had to be accompanied by adequate safeguards -- a detention barn, a top testing laboratory -- or it could be used to hide the presence of illegal drugs in a horse's system.

In some states, racing fans could see that Lasix was associated with outlandish form reversals, and they became very cynical about the drug. In many states, bettors are not told who is getting Lasix, and they became doubly cynical: what were the vets and the horsemen trying to hide? Having helped create all these suspicions, the vets are going to have a hard time ever convincing the public that Lasix is, indeed, an ideal therapeutic medication.

As important as the debate over these weighty issues might be, I was more interested in hearing behind-the-scenes gossip about the latest fashions in illegal drugs. One well-informed vet said there is a typical route for narcotics to reach the track. They are usually developed by European chemical companies; they are used first at quarter-horse tracks where, in the common view, anything goes. If they are effective, they wind up in thoroughbred racing.

The most talked-about illegal drug in the game today is called M99, nicknamed "elephant juice," because it is so potent it is used as a tranquilizer for elephants.

"The dose for most drugs is measured in milligrams," a state vet told me. "M99 is so powerful that it's measured in nanograms. It's a dangerous drug to use because the doses are so small and there's a very narrow effective range. One day at the track where I was working, two horses dropped dead walking into the paddock. I was a little suspicious."

When they see horses abused by illegal drugs, but are frequently prevented by the rules of racing from using medications they feel are benign and therapeutic, it's easy to understand why race track veterinarians feel a little frustrated.