11/17/2011 1:05PM

Lasix: Demystifying the drug, methods of training without it

Staff illustration

Soon after leaving the service in the mid-1940s, Mel Stute went to work as a groom for trainer Yorkie McLeod at the old Tanforan Racetrack near San Francisco. McLeod had a funny way of trying to prevent his horses from the age-old problem of bleeding. He would ask his young groom to wrap copper wire around the base of a horse’s tail before a race − thin, eight-inch strips of the sort you would find in hardware stores.

“I’d put it on as late as I could before going to the receiving barn, which was an hour before the race then,” said Stute, 84, who has been training in California for more than six decades. “You’d tighten it tight enough so they could feel it.”

The teenager did what he was told, however strange it sounded. Stute laughs now thinking about it.

“I don’t think it really helped, but it helped you mentally,” he said.

The copper wire was ostensibly meant to be a tourniquet, as if the tail was a gateway to the lungs and held magical powers of coagulation. Pricking a horse’s ears would’ve been as effective, which is to say not at all. And McLeod wasn’t a slouch. He trained outstanding fillies Levee and Marshua and won the 1956 Travers. But it goes to show what horsemen might try to prevent bleeding in the lungs, what veterinarians now call Exercise-Induced Pulmonary Hemorrhaging (EIPH).

This type of horsemanship was before the dawn of the diuretic furosemide, otherwise known by its brand name, Lasix. An old wives’ tale like this one gave way to the modern medical reality of using a single drug. But Lasix may soon be on its way out, forcing trainers to mine the past and present for new ideas.

How would training change in America without Lasix? As the first drug allowed for raceday use, beginning in the early 1970’s, Lasix cut a line through the history of American racing. Permissive medication programs followed. Legal in every state with racing since 1995, almost every horse in the country today races on Lasix. Its popularity has no peer − among horsemen.

Racing organizations who represent the industry, such as the Jockey Club and Graded Stakes Committee, have committed to banning Lasix. The Breeders’ Cup plans to do just that in its 2-year-old races next year and all of its races in 2013.

Why Lasix, and why now? Given its universality and its visibility as the first raceday medication, it’s a symbol for the ways in which North American racing stands apart. In Europe, Asia, and much of the racing world, it’s illegal on raceday and barred from training in some of these places. The worst bleeders in Hong Kong and Germany are even forced to retire and are excluded from breeding.

Lasix has been scientifically validated, but these groups see the original rationale coined four decades ago by horsemen and racetrack operators and veterinarians – that Lasix would help horses withstand the rigors of additional racing – as unsupported by the evidence today. They see sour notes everywhere, an orchestra of declines in foal crops, bloodstock prices, field sizes, starts per year, and, most damningly, public perception and integrity. Federal regulations knock on the door. Lasix is only one factor, but it is seen as the key that unlocks the door into a drug-free sport. 

That door could open to a bitter standoff. In August, horsemen successfully turned back a move by Frank Stronach to outlaw Lasix as well as other raceday medications at the new Gulfstream Park meet.

“I think that probably in this day and age, a 12- or 15-dollar shot of Lasix is going to be a lot cheaper than trying other things, that are natural, are okay, but yet don’t work as well and are more expensive,” trainer Kiaran McLaughlin said. With a slight laugh, he added: “The best thing is to probably keep Lasix.”

Two generations of trainers have depended on paying a veterinarian a few bucks for a shot that in the short-term corrects an ailment that past horsemen formulated inventive approaches to prevent.

But change appears on the way, awakening the past. Horsemen won’t need to stock up on copper wire, but the methods employed to prevent and treat bleeding might soon be back in their hands. What are the alternatives to Lasix? The answers are fundamental and medical. And the lore of how to manage bleeders, preserved in the minds of a dwindling few, may prove valuable.


Demystifying the science behind this complex, emotional issue is important. Knowing what EIPH is, how it occurs, and how Lasix addresses it informs the options available to horsemen if Lasix is indeed phased out. So much also depends on one’s definition of bleeding.

EIPH occurs when the thin capillaries that line a horse’s lungs are exposed to high pressure during exercise; the faster a horse runs, the more likely these capillaries will leak or burst. Blood can make its way into the trachea and, in the most severe cases, pour from the nostrils. As nose-breathing animals, horses can have their respiration and hence their performance affected by serious bleeding.

Studies have shown that upward of 90 percent of horses show a trace of blood in their windpipes after a race or workout. On the other hand, the worst cases – visual bleeding from the nose, or epistaxis as vets call it – occur in less than 1 percent of horses.

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A recent experiment by American, Australian, and South African researchers followed a sample of South African horses and found that 79 percent showed some trace of blood after racing without Lasix. In the study, the common veterinary practice was used of grading bleeding on a scale of 1-4 upon scoping. Vets agree that bleeding at a grade of 1 doesn’t affect performance, 2 is on the border, and 3 and 4 definitely reduce performance.

In the group of horses not treated with Lasix, 20 percent didn’t bleed, 45 percent bled at the 1 level, and another 25 percent bled at the 2 level. For the Lasix group, 43 percent didn’t bleed, 48 percent bled at the 1 level, and 9 percent bled at the 2 level.

Horses who raced with Lasix still bled 57 percent of the time. However, Lasix eliminated the most serious cases of bleeding. It works. As a powerful diuretic it reduces pressure on the thin capillaries through dehydration. That reduces the “remodeling” of blood vessels and scarring of lung tissue, which prevents recurring episodes.

Of course, among the horses who ran without Lasix, not quite 10 percent bled to a degree expected to reduce performance. In another presentation given at the NTRA summit, Edward Robinson of Michigan State referenced an Australian study in which the number was about 5 percent.


Endoscopes can detect traces of blood in the trachea; only severe cases (right) result in bleeding out of the nostrils. Below, an endoscope shows the four grades of bleeding. Photo at right: Barbara D. Livingston

Normal trachea with no blood.

Presence of one or more flecks of blood in the trachea. Performance is not affected.

One long stream of blood (more than half the length of the trachea) or multiple streams of blood (less than one third of the trachea). May or may not affect performance.

Multiple streams of blood covering more than one third of the trachea. Performance is reduced.

Blood covers nearly all of the trachea, often causing bleeding out of the nostrils. Performance is reduced.

Why then is Lasix used by 95 percent of American horses if only a small percentage is seriously affected by EIPH? As mentioned, studies show that bleeding gets worse over time. More importantly, because Lasix typically reduces the severity and frequency of bleeding and leads to weight loss before a race – 16 pounds more for users than non-users, according to the South African study – it enhances performance.

In the 1980’s, studies commissioned by The Jockey Club and led by researchers at the University of Pennsylvania originally supplied this evidence. Over a mile distance, Lasix improved the performance of bleeders by an average of 1.3 lengths and the performance of non-bleeders by 2.4 lengths.

“You could argue a horse only goes back to its normal ability,” said veterinarian George Maylin, who has led New York’s drug testing laboratory for 40 years, “but certainly, horses that are administered furosemide do change their performance.”

Giving Lasix is seen by trainers as prudent management. Its widespread use makes opting out a lonely position. So horses begin training on it before they ever race. Before the invention of endoscopes in the 1970’s, bleeding was defined by those rare instances of epistaxis; there was no other way to spot it. Because bleeding is intrinsic to equine anatomy – and can be detected at minute levels by fiber-optic scopes – it is now broadly defined to encompass all horses.

“Whether they need it or not, who the heck knows?” longtime trainer Jonathan Sheppard said. “But it’s a preventative thing.”


Horses have bled for as long as people have been racing them, but for most of those 300 years there wasn’t much done about it. What was done, however, might offer examples of what to do and what not to do for trainers now.

On a recent morning at Belmont Park, octogenarian Hall of Fame trainer Allen Jerkens was asked about past practice.

“Some people had crazy ideas about it,” he said, chuckling. “They put a copper wire around his tail. I never did it, but I know that was one of the things they said to do.”

Asked for the guilty party, Jerkens shot his head back and laughed. “I won’t swear by it,” he said, “but I think it was Max Hirsch.”

Hirsch won all the big races, several times over, and trained many champions, among them 1946 Triple Crown winner Assault.

From east to west, this old wives’ tale had traction. Partly, it reflects the confusion over the causes of EIPH, itself a modern term. Some believed bleeding emanated from burst nasal capillaries rather than the lungs. Jerkens also pointed out that only the worst cases were seen.

“Unless they bled visually out of their nose we wouldn’t know,” he said. “And if they just bled out of one nostril, the old-timers used to say, ‘That won’t bother them, that’s just a little sinus trouble.’ ”

Trainers still took what they believed were precautionary measures. One common example was “drawing” a horse – taking away its hay and water at least six hours before a race, maybe even the night before. It was a blunt method of dehydration.

Jerkens pointed to a fitter, sturdier animal as another reason why bleeding was considered atypical in the 1950’s and 1960’s. He said none of his good horses were bleeders.

“Horses worked a lot harder in those days,” he said. “The strain on them in the race wasn’t as much as the strain is on them now. They trained almost as hard in the morning as they did when they ran.”

The best horses would often work the full distance of an upcoming race five or six days before, breeze a half-mile two days out, and maybe even an eighth of a mile the morning of the race. As but one example, three days before Assault finished off the Triple Crown, Max Hirsch sent the colt out for a 12-furlong breeze in 2:32 at Belmont.

In his early years as a trainer, Mel Stute would regularly blow out his horses two or three furlongs the morning of the race. He learned this from his late brother Warren, who also trained in California for six decades.

“It might take the congestion out of their lungs,” he said. Did it prevent bleeding? “You hoped so, but you went by feel.”

In 1961, Stute bought First Balcony off Frank Martin, and the horse bled the first time he ran him. So he drew him the night before and breezed him the morning of the $100,000 Californian. An 11-1 longshot, First Balcony gave Stute his first stakes win.

Other ideas come out of interviews and literature from those days. In his original 1942 edition of “Training For Fun, and Profit − Maybe!” trainer/steward Keene Daingerfield suggested using cold salt water to stop bleeding, although prevention escaped mention. He said chronic bleeders were barred from racing. In a revised edition in 1948, Daingerfield wrote, “Intravenous injections of calcium gluconate or related compounds have proved beneficial to some chronic bleeders.” He went on to say that he’d never had a chronic case.

In his exhaustive 1953 manual “Training Thoroughbred Racehorses,” Hall of Fame trainer Preston Burch devoted two chapters to dozens of ailments and injuries but, revealingly, didn’t include bleeding.

Legendary trainer John Nerud, 98, said he only had one chronic bleeder in his long career. He said one out of 10 times he would spot a little blood on the grass where a horse grazed after racing. To these horses he would give iron, Vitamin B12, and ascorbic acid, which is a form of Vitamin C. Other elderly trainers mentioned using Vitamins K and B1. All of these vitamins were supposed to address the proteins in blood coagulation. Injected estrogen such as Premarin has also been used for that goal.

Nerud also offered a simpler strategy for treating the ailment: “Keep them fat and happy, and don’t work them too hard. Give them the chance to heal up, and usually, they would.”

There weren’t peer-reviewed studies in those days. These were horsemen hoping something stuck. Some methods were laughable, others perhaps made more sense. Most lack scientific evidence today.

Nathan Slovis, the director of the McGee Medical and Critical Care Center at the Hagyard Equine Medical Institute in Lexington, said these vitamins would not affect coagulation unless the animals were deficient. He said drawing a horse – he knows trainers in England and Hong Kong who do this – would decrease body water and hence decrease blood pressure for racing, but he wouldn’t recommend it. There is no scientific evidence that administering estrogen or calcium gluconate prevents bleeding.

Some alternative treatments that have received scientific support for preventing or treating EIPH are nasal dilators, a diet rich in Omega-3 fatty acids, and rest. Hyperbaric oxygen therapy is another form of treatment offering encouraging signs. On the count of rest, Nerud had the right idea. It can take burst capillaries two to three weeks to repair themselves, and horses shouldn’t undergo strenuous exercise during that time.

Studies into these treatments are still in their infancy because nobody has been in a rush to replace furosemide. In the beginning, however, its effects were unknown.

“It’s one of the things that vets would bring around, saying, ‘I’ve got this great thing,’ ” trainer Jimmy Toner said. “It was first used to settle fillies down. We didn’t realize it was stopping the bleeding. And then a couple of years after that it started to be regulated.”

Drug testing was urine-based then, and since Lasix flushes out horses it was seen as a potential masking agent. Moreover, the public was largely kept in the dark until Lasix was included in past performances in 1990. At the Washington Post in the 1970’s, Andy Beyer wrote often about its suspected role in form reversals.

Alex Harthill, who more than any other veterinarian begat the era of permissive medication, popularized Lasix. A few years before his death in 2005, he was asked about its introduction.

“It started with me,” he said. “I used it on Northern Dancer in 1964.”

Northern Dancer won the Kentucky Derby by a nose over Hill Rise. Illegal and unknown then, one can only guess what effect Lasix had on his performance.

Embraced by horsemen and racetrack operators, Lasix was first legalized by the Maryland racing commission for raceday use – reportedly with little or no controls – in 1974. By 1976, Florida, Michigan, New Jersey, Kentucky, Illinois, Pennsylvania, and other states had followed. Supporters argued it would allow horses to handle the rigors of a full-year schedule. Horses then averaged about 10 starts per year.

The original rigid scopes gave way to flexible endoscopes in the early 1980’s. Once minute amounts of blood could be detected, trainers could argue that their horse deserved to race on Lasix. Nowadays, every jurisdiction affords Lasix, no proof required.

New York held out until September 1995. Fearful of losing horses, it made a business decision to legalize it. Ted Hill, formerly the chief veterinarian for the New York Racing Association and now a steward at NYRA, had collected data on the number of bleeders from 1976 until its introduction. The highest number of visual bleeders in one year was 70, or 0.3 percent of starters, and the low was 24, less than 0.1 percent. Since Lasix was introduced on raceday in New York, the range has gone from 5 to 18.

Lasix made a significant difference by reducing the number of horses observed bleeding on the track. But there weren’t many to begin with, Hill said.

“Personally, I was never convinced it was really something we needed,” he said. “Of course, the fiber-optic endoscope changed how we diagnosed EIPH, and the rest is history.”


American racing without Lasix might require hard-to-enact changes. For starters, environmental factors play a role in EIPH, Slovis said. He recommended keeping dust levels down, feeding hay on the ground, and ensuring better ventilation in stalls.

Unlike their European counterparts, American racetracks are situated in some of the densest, dustiest, most polluted areas. Aqueduct sits next to John F. Kennedy Airport, Hollywood Park near Los Angeles International Airport, Arlington Park close to an industrial park outside Chicago.

It is indisputable that horses benefit from time away from the track in less stressful environments. Jonathan Sheppard, who trains at his own farm in rural Pennsylvania, said his horses breathe clean air in the fresh countryside and are turned out in paddocks for an hour or more every morning.

“My vet says that we have far less respiratory problems than even other farms in the area,” Sheppard said. “Bleeding is under that heading.”

Sheppard’s methods aren’t so different from those used in Europe, where most horses train at yards away from the track. Gina Rarick, formerly an American journalist who became a trainer in France in 2000, said the conditioning of horses and the environment are major deterrents of bleeding. She said bleeding is mitigated or altogether prevented by proper husbandry, feeding, and endurance-focused training.

“Nobody is worried about Lasix, and nobody is worried about bleeding here,” Rarick said. She is vehemently opposed to permissive medication use. “A little bit of capillary bleeding is built into the animal.” Offering an analogy, she added, “All men grow beards. Are you going to use drugs to stop that?”

The training style is altogether different in Europe, befitting its style of racing. Rarick has her horses gallop and trot about six miles a day, all with riders on their backs. She breezes her horses 1 1/4 miles two or three days a week and gives them a fast, head-to-head, half-mile gallop three or four days before a race. Rarick never draws her horses; she’ll give them water up to an hour before post time.

Her conditioning regimen – so unlike the short, fast breezes that are common in America and reflect our racing program – rings truer to the way men such as Jerkens used to train before anybody had ever heard of Lasix.

Without Lasix, would a similar style of training take hold here? Graham Motion, trainer of Kentucky Derby winner Animal Kingdom, said five trainers would give five different answers. For his part, he wouldn’t train a bleeder as hard so as to avoid exacerbating the condition. He said this is already a consideration for the worst bleeders since Lasix isn’t a cure-all.

Slovis concurred. He said he has talked to veterinarians in Hong Kong who report that some of the best trainers there utilize low-intensity exercise over long distances so that the horses suffer less “wear and tear” on their respiratory system.

Recovery is important, too, and Motion is a fan of hyperbaric oxygen chambers, in which he has found success with healing lung damage and other ailments.

The differences in American and European racing are, in fact, sometimes marshaled as counter-arguments here in support of Lasix. Tracks aren’t moving anywhere, and horses aren’t relocating en masse to farms. Additionally, most of the foreign trainers who ran horses in the Breeders’ Cup took the option to administer Lasix.

“Maybe the rest of the world would like to have it,” Kiaran McLaughlin said. “You don’t know those answers.”

McLaughlin gave voice to an opinion heard from several other trainers that Europe and Asia may not have fewer bleeders than America.

“Worldwide they don’t scope as often because there’s not a lot they can do about one bleeding a little bit,” he said.

However, McLaughlin is not alone in reading the tea leaves. Six of his youngsters, including Champagne runner-up Alpha, have raced without Lasix. They didn’t need it. With almost every horse nowadays racing on Lasix regardless of true need, it’s a logical though novel approach.

McLaughlin is adapting, as others will, too. Sheppard likened it to taking away a baby’s pacifier. The baby goes bonkers for a bit, then adjusts to the new situation. 

After all, solving the mysteries of these animals is simply what trainers do. Science is clearer now than in the days of old wives’ tales, when copper wire doubled as a tourniquet. Trial-and-error can be expected. As befits a game in which large purses are on the line and larger sums wagered, like careful detectives the clues trainers find post-Lasix will be held dearly.

“If I had a secret weapon I wouldn’t tell you,” Sheppard said with a dry laugh. “I don’t – but I wouldn’t want it published if I did.”


Among his early, pre-Lasix methods to prevent bleeding was blowing out his horses the morning of a race to "take congestion out of their lungs." On whether the method worked: "You hoped so, but you went by feel."


Recalling an era before Lasix was scientifically validated, he said, "It's one of the things vets would bring around and say, ‘I've got this great thing.' We didn't realize it was stopping the bleeding."


He suggests the alternatives to Lasix as a means to prevent or treat bleeding may be more expensive and less effective, adding, "The best thing is to probably keep Lasix."


Known for his natural training methods, he said keeping his horses in a less stressful environment has helped them have fewer respiratory problems. "Bleeding is under that heading," he said.


She is opposed to permissive medication use and points to conditioning and the environment as deterrents to bleeding. Based in France, she said, "Nobody is worried about Lasix, and nobody is worried about bleeding here."