Lasix – the great debate

What is the racehorse?

“The Thoroughbred exists because its selection has depended, not on experts, technicians, or zoologists, but on a piece of wood: the winning post of the Epsom Derby. If you base your criteria on anything else, you will get something else, not the Thoroughbred.” – Federico Tesio

As per those immortal words from Federico Tesio, selective breeding for a horse that could carry weight over distance at a sustained speed began in 17th and 18th-century England.  There are many romantic descriptions of the modern product – “The blood runs hot in the Thoroughbred, the courage runs deep and their pride is limitless.  This is their heritage, and they carry it like a banner” – C.V. Anderson.  ‘The Thoroughbred is deep through the heart not only in conformation but in fighting spirit and the love of running and competing is inherent now in the breed’s nature.’

Unfortunately the truth is that we have increasingly bred for brilliance on the racetrack and ruthless pursuit of speed has come at a cost.  Racehorses are expected to perform at maximum exertion.  While that is not necessarily a bad thing, the fact that they are expected to do it repeatedly places extraordinary stresses and strains on them physiologically.  And while the body is made of malleable and adaptive structures, these do have physiological limits and pushing an animal to or beyond those limits on a regular basis comes at a cost.  In short, something’s got to give at some point.  And we see this expressed in a myriad of different ways – from high accident rates to health problems such as bleeding from the lungs, low fertility, abnormally small hearts and a small hoof to body mass ratio.

One of the most prevalent unsoundness to face owners and trainers is bleeding or EIPH (exercise induced pulmonary haemorrhage).  It has become the subject of hot debate recently, with particular focus on furosemide, an anti-bleeding diuretic that also goes by the trade names of Lasix or Salix.

Although the drug has been commonly used in the US since the 1970’s, it is banned on race days in all major racing jurisdictions outside North America due to its alleged performance-enhancing qualities and a lot of international pressure is currently being brought to bear on North America to abandon its use of race day medication in general and Lasix in particular.

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Belmont Summit

During the week of the Kentucky Derby, U.S. Senator Tom Udall of New Mexico and U.S. Congressman Ed Whitfield of Kentucky filed federal bills calling for a ban on all performance-enhancing drugs in horse racing and proposing a three-strikes-and-you’re-out penalty system.

With a reported 95% of US horses racing on Lasix, this proposal has evoked a strong response amongst industry professionals.

In response, The National Thoroughbred Racing Association (NTRA), the American Association of Equine Practitioners, and the Racing Medication and Testing Consortium put together a 2-day International Summit to discuss Race Day Medication, EIPH and the Racehorse.  It was held on 13 June 2011 at Belmont Park in Elmont, N.Y. and was attended by more than 100 people representing nine countries on six continents.  Among the panellists was our very own Dr John McVeigh, BVMS, MRCVS of Baker & McVeigh Veterinary Hospital.

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So Why All The Fuss ?

Although it was originally believed that ‘bleeds’ originated in the nose, W. Robert Cook, F.R.C.V.S., Ph.D. suggested that epistaxis originated from the lungs, a theory that John Pascoe, B.V.Sc., confirmed when he made use of a fibre optic bronchoscope to determine without question that the bleeding originated in the lungs.

Bleeding is a result of the blood in the lungs and respiratory organs being put under enormous pressure under exercise stress.  If the pressure exceeds the capabilities of the blood vessels, then the thin capillaries rupture causing bleeding in the airways.

Vets grade episodes of bleeding into 4.

Grade 1: Flecks of blood or a single short stream of blood extending less than a quarter of the tracheal (windpipe) length.

Grade 2: One continuous stream of blood extending at least one half the length of the trachea or multiple streams of blood covering less than one third of the tracheal surface.

Grade 3: Multiple streams of blood covering more than one third of the tracheal surface.

Grade 4: Abundant blood in the trachea, completely covering the tracheal surface and pooling at the thoracic inlet.

While small bleeds are relatively common (it is believed that nearly all horses experience EIPH when exposed to strenuous exercise) only a few (less than 10%) will bleed through the nostrils.  Unfortunately, the healing process includes remodelling of blood vessels and scarring of the lung tissue, which makes the tissues less pliable.  This in turn makes the animal more susceptible to subsequent bleeds, scarring and a potential decrease in lung function over time.

Furosemide was originally marketed as Lasix for use in humans to treat high blood pressure.  It was approved in the 1970s for equine use to treat horses with EIPH.  Lasix is a diuretic and works to lower a horse’s blood pressure.  In particular, this can reduce the pressure on the very thin capillaries in the horse’s lung by some 15-20%.  So it can be used preventatively to manage blood pressure, thereby reducing or even eliminating bleeding and the subsequent scarring in the lungs and avoiding more profound bleeding incidents further down the line.

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So why don’t we simply put all our horses on it ?

It seems there is some debate as to whether the drug offers definitive benefits to the horse.  Eric Birks, D.V.M., Ph.D. from the University of Pennsylvania’s New Bolton Center states that ‘horses given Salix lose weight.  Yes, they do have a decrease in blood pressure within the circulation of the lungs, but it is not a therapeutic change.’  “Actually, the horse is likely to perform better because it has lost weight.”

A recent study was conducted by researchers from the US, Australia and South Africa to investigate the effects of Lasix on several hundred race horses in South Africa.  In the study, 79% of horses showed some signs of blood after racing without Lasix, but so did 57% of those that raced with Lasix.  So, while Lasix did appear to reduce both the incidence and the severity of bleeding in a majority of horses, it didn’t eliminate it.

In the South African study, horses treated with Lasix lost an average of 28 pounds pre-race, while those treated with a placebo lost only 12 pounds.  That 16-pound advantage would be considered significant by almost any handicapper.  Whatever the mechanism, horses on Lasix do better.  That’s why 95% of US race horses run on Lasix, even though, based on the South African study, fewer than 10% of those horses would bleed at a level that substantially interfered with their performance if they raced without the drug.

Another concern is that Lasix can dehydrate a horse that is getting ready to race.  This dilutes the urine and makes it difficult to detect illegal drugs.  Its alleged use as a masking agent for other drugs is one of the reasons furosemide is included on the World Anti-Doping Agency‘s banned drug list.

However, most worrying is that it seems there might be a genetic link to EIPH.  At the recent Belmont Summit, John McVeigh raised the heritability of exercise-induced pulmonary haemorrhaging.  A study completed back in 2004 called “A genetic analysis of epistaxis as associated with EIPH in the Southern African Thoroughbred” seems to indicate genetic links between EIPH and certain bloodlines.

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People who are for it

For Kelly Breen, race-day medication issues were important enough that the trainer addressed the topic moments after saddling Ruler On Ice to a Belmont Stakes (G1) victory.

“We have a horse that ran in the Kentucky Derby, Pants On Fire, that bled through Lasix [Salix],” Breen said. “And I know it seems like everybody talks about the problems with medication and horses, but when you have a horse that you think that highly of, and you have something that we know stops horses from bleeding in Lasix, I don’t understand why they’re trying to take it away.”

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The Debate

Dr. W. Robert Cook, Professor of Surgery Emeritus at Tufts University is of the opinion that bleeding not a disease, it is a symptom and using furosemide to treat EIPH will not have a positive effect on bleeding until the cause of the bleeding is determined and remedied.

But if that cause is genetic, and horses are being treated with Lasix to keep them racing and performing and then moving on into the breeding barn, is it any wonder that we are seeing an increasing number of incidents of EIPH ?

Being able to mask a problem like bleeding affects the integrity of our race results, our stud stallions and our breed as a whole and adds yet another element of chance into the genetic lottery.

And so it seems we may be the architects of our own fates after all.

Interestingly, one of the findings of the recent summit is that the Flair nasal strip has much the same effect on bleeding as Lasix does, so perhaps there is still a chance for horses like Pants On Fire.  There have even been suggestions of creating a special register for bleeders which will allow them to compete, but not to be used for breeding purposes.

I think the banning of race day medications and Lasix in particular can only be a good thing for the industry and is in fact imperative for the future well-being of our horses.

The breakdown of Eight Belles in the 2008 Kentucky Derby precipitated sweeping changes including eliminating anabolic steroids, standardizing equine injury reporting, the launching of the NTRA Safety and Integrity Alliance, and increasing equine aftercare efforts.  However, continued incidents of high-profile catastrophic race day injuries have resulted in increasing pressure from the public and animal rights groups to clean things up.

“Once you introduce performance-enhancing drugs into a trainer’s arsenal, you really are asking from trouble, certainly from the betting public’s point of view,” said Dr. Treve Williams, a veterinarian in Australia and it is true that racing can no longer make decisions in an industry vacuum.

John Della Volpe, of SocialSphere Inc said “This is the era of transparency, the era of sunlight.  Consumers expect and demand authenticity and transparency.”

Yes indeed.

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