EIPH - could there be links to sudden death and pulmonary haemorrhage?
Dr Peter W. Physick-Sheard, BVSc, FRCVS, explores preliminary research and hypotheses, being conducted by the University of Guelph, to see if there is a possibility that these conditions are linked and what this could mean for future management and training of thoroughbreds.
"World's Your Oyster,” a three-year-old thoroughbred mare, presented at the veterinary hospital for clinical examination. She won her maiden start as a two-year-old and placed once in two subsequent starts. After training well as a three-year-old, she failed to finish her first start, easing at the top of the stretch, and was observed to fade abruptly during training. Some irregularity was suspected in heart rhythm after exercise. Thorough clinical examination, blood work, ultrasound of the heart and an ECG during rest and workout revealed nothing unusual.
Returning to training, Oyster placed in six of her subsequent eight starts, winning the last two. She subsequently died suddenly during early training as a four-year-old. At post-mortem, diagnoses of pulmonary haemorrhage and exercise-induced pulmonary haemorrhage were established—a very frustrating and unfortunate outcome.
Across the racing world, a case like this probably occurs daily. Anything that can limit a horse's ability to express its genetic potential is a major source of anxiety when training. The possibility of injury and lameness is the greatest concern, but a close second is respiratory disease, with bleeding from the lungs (most often referred to as exercise induced pulmonary [lung] haemorrhage or EIPH) being high on the list.
EIPH is thought to occur in as many as 85 percent of racehorses, and may initially be very mild without obvious clinical consequences. In some cases it can be associated with haemorrhage of sufficient severity for blood to appear at the nostrils, even at first occurrence. In many racing jurisdictions this is a potentially career-ending problem. In these horses, an impact on performance is unquestionable. Bleeding from the lungs is the reason for the existence of ‘Lasix programs,’ involving pre-race administration of a medication considered to reduce haemorrhage. Such programs are controversial—the justifications for their existence ranging from addressing welfare concerns for the horse to dealing with the performance impacts.
Much less frequently encountered is heavy exercise-associated bleeding from the nostrils (referred to as epistaxis), which can sometimes be accompanied by sudden death, during or shortly after exercise. Some horses bleed heavily internally and die without blood appearing at the nostrils. Haemorrhage may only become obvious when the horse is lying on its side, or not until post-mortem. Affected animals do not necessarily have any history of EIPH, either clinically or sub-clinically. There is an additional group of rare cases in which a horse simply dies suddenly, most often very soon after work and even after a winning performance, and in which little to nothing clearly explains the cause on post-mortem. This is despite the fact most racing jurisdictions study sudden death cases very closely.
EIPH is diagnosed most often by bronchoscopy—passing an endoscope into the lung after work and taking a look. In suspected but mild cases, there may not be sufficient haemorrhage to be visible, and a procedure called a bronchoalveolar lavage is performed. The airways are rinsed and fluid is collected and examined microscopically to identify signs of bleeding. Scoping to confirm diagnosis is usually a minimum requirement before a horse can be placed on a Lasix program.
Are EIPH, severe pulmonary haemorrhage and sudden death related? Are they the same or different conditions?
At the University of Guelph, we are working on the hypothesis that most often they are not different—that it’s degrees of the same condition, or closely related conditions perhaps with a common underlying cause. We see varying clinical signs as being essentially a reflection of severity and speed of onset of underlying problems.
Causes in individual cases may reflect multiple factors, so coming at the issues from several different directions, as is the case with the range of ongoing studies, is a good way to go so long as study subjects and cases are comparable and thoroughly documented. However, starting from the hypothesis that these may all represent basically the same clinical condition, we are approaching the problem from a clinical perspective, which is that cardiac dysfunction is the common cause.
Numerous cardiac disorders and cellular mechanisms have the potential to contribute to transient or complete pump (heart) failure. However, identifying them as potential disease candidates does not specifically identify the role they may have played, if any, in a case of heart failure and in lung haemorrhage; it only means that they are potential primary underlying triggers. It isn't possible for us to be right there when a haemorrhage event occurs, so almost invariably we are left looking at the outcome—the event of interest has passed. These concerns influence the approach we are taking.
Background
The superlative performance ability of a horse depends on many physical factors:
Huge ventilatory (ability to move air) and gas exchange capacity
Body structure including limb length and design - allows it to cover ground rapidly with a long stride
Metabolic adaptations - supports a high rate of energy production by burning oxygen, tolerance of severe metabolic disruptions toward the end of race-intensity effort
High cardiovascular capacity - allows the average horse to pump roughly a brimming bathtub of blood every minute
At race intensity effort, these mechanisms, and more, have to work in coordination to support performance. There is likely not much reserve left—two furlongs (400m) from the winning post—even in the best of horses. There are many wild cards, from how the horse is feeling on race day to how the race plays out; and in all horses there will be a ceiling to performance. That ceiling—the factor limiting performance—may differ from horse to horse and even from day to day. There’s no guarantee that in any particular competition circumstances will allow the horse to perform within its own limitations. One of these factors involves the left side of the heart, from which blood is driven around the body to the muscles.
A weak link - filling the left ventricle
The cardiovascular system of the horse exhibits features that help sustain a high cardiac output at peak effort. The feature of concern here is the high exercise pressure in the circulation from the right ventricle, through the lungs to the left ventricle. At intense effort and high heart rates, there is very little time available to fill the left ventricle—sometimes as little as 1/10 of a second; and if the chamber cannot fill properly, it cannot empty properly and cardiac output will fall. The circumstances required to achieve adequate filling include the readiness of the chamber to relax to accept blood—its ‘stiffness.’ Chamber stiffness increases greatly at exercise, and this stiffened chamber must relax rapidly in order to fill. That relaxation seems not to be sufficient on its own in the horse at high heart rates. Increased filling pressure from the circulation draining the lungs is also required. But there is a weak point: the pulmonary capillaries.
These are tiny vessels conducting blood across the lungs from the pulmonary artery to the pulmonary veins. During this transit, all the gas exchange needed to support exercise takes place. The physiology of other species tells us that the trained lung circulation achieves maximum flow (equivalent to cardiac output) by reducing resistance in those small vessels. This process effectively increases lung blood flow reserve by, among other things, dilating small vessels. Effectively, resistance to the flow of blood through the lungs is minimised. We know this occurs in horses as it does in other species; yet in the horse, blood pressure in the lungs still increases dramatically at exercise.
If this increase is not the result of resistance in the small vessels, it must reflect something else, and that appears to be resistance to flow into the left chamber. This means the entire lung circulation is exposed to the same pressures, including the thin-walled capillaries. Capillaries normally work at quite low pressure, but in the exercising horse, they must tolerate very high pressures. They have thin walls and little between them, and the air exchange sacs in the lung. This makes them vulnerable. It's not surprising they sometimes rupture, resulting in lung haemorrhage.
Recent studies identified changes in the structure of small veins through which the blood flows from the capillaries and on toward the left chamber. This was suspected to be a pathology and part of the long-term consequences of EIPH, or perhaps even part of the cause as the changes were first identified in EIPH cases. It could be, however, that remodelling is a normal response to the very high blood flow through the lungs—a way of increasing lung flow reserve, which is an important determinant of maximum rate of aerobic working.
The more lung flow reserve, the more cardiac output and the more aerobic work an animal can perform. The same vein changes have been observed in non-racing horses and horses without any history or signs of bleeding. They may even be an indication that everything is proceeding as required and a predictable consequence of intense aerobic training. On the other hand, they may be an indication in some horses that the rate of exercise blood flow through their lungs is a little more than they can tolerate, necessitating some restructuring. We have lots to learn on this point.
If the capacity to accommodate blood flow through the lungs is critical, and limiting, then anything that further compromises this process is likely to be of major importance. It starts to sound very much as though the horse has a design problem, but we shouldn't rush to judgement. Horses were probably not designed for the very intense and sustained effort we ask of them in a race. Real-world situations that would have driven their evolution would have required a sprint performance (to avoid ambush predators such as lions) or a prolonged slower-paced performance to evade predators such as wolves, with only the unlucky victim being pushed to the limit and not the entire herd.
Lung blood flow and pulmonary oedema
There is another important element to this story. High pressures in the capillaries in the lung will be associated with significant movement of fluid from the capillaries into lung tissue spaces. This movement in fact happens continuously at all levels of effort and throughout the body—it's a normal process. It's the reason the skin on your ankles ‘sticks’ to the underlying structures when you are standing for a long time. So long as you keep moving a little, the lymphatic system will draw away the fluid.
In a diseased lung, tissue fluid accumulation is referred to as pulmonary oedema, and its presence or absence has often been used to help characterise lung pathologies. The lung lymphatic system can be overwhelmed when tissue fluid is produced very rapidly. When a horse experiences sudden heart failure, such as when the supporting structures of a critical valve fail, one result is massive overproduction of lung tissue fluid and appearance of copious amounts of bloody fluid from the nostrils.
The increase in capillary pressure under these conditions is as great as at exercise, but the horse is at rest. So why is there no bloody fluid in the average, normal horse after a race? It’s because this system operates very efficiently at the high respiratory rates found during work: tissue fluid is pumped back into the circulation, and fluid does not accumulate. The fluid is pumped out as quickly as it is formed. An animal’s level of physical activity at the time problems develop can therefore make a profound difference to the clinical signs seen and to the pathology.
Usual events with unusual consequences
If filling the left ventricle and the ability of the lungs to accommodate high flow at exercise are limiting factors, surely this affects all horses. So why do we see such a wide range of clinical pictures, from normal to subclinical haemorrhage to sudden death?
Variation in contributing factors such as type of horse, type and intensity of work, sudden and unanticipated changes in work intensity, level of training in relation to work and the presence of disease states are all variables that could influence when and how clinical signs are seen, but there are other considerations.
Although we talk about heart rate as a fairly stable event, there is in fact quite a lot of variation from beat to beat. This is often referred to as heart rate variability. There has been a lot of work performed on the magnitude of this variability at rest and in response to various short-term disturbances and at light exercise in the horse, but not a lot at maximal exercise. Sustained heart rate can be very high in a strenuously working horse, with beats seeming to follow each other in a very consistent manner, but there is in fact still variation.
Some of this variation is normal and reflects the influence of factors such as respiration. However, other variations in rate can reflect changes in heart rhythm. Still other variations may not seem to change rhythm at all but may instead reflect the way electrical signals are being conducted through the heart.
These may be evident from the ECG but would not appear abnormal on a heart rate monitor or when listening. These variations, whether physiologic (normal) or a reflection of abnormal function, will have a presently, poorly understood influence on blood flow through the lungs and heart—and on cardiac filling. Influences may be minimal at low rates, but what happens at a heart rate over 200 and in an animal working at the limits of its capacity.
Normal electrical activation of the heart follows a pattern that results in an orderly sequence of heart muscle contraction, and that provides optimal emptying of the ventricles. Chamber relaxation complements this process.
An abnormal beat or abnormal interval can compromise filling and/or emptying of the left ventricle, leaving more blood to be discharged in the next cycle and back up through the lungs, raising pulmonary venous pressure. A sequence of abnormal beats can lead to a progressive backup of blood, and there may not be the capacity to hold it—even for one quarter of a second, a whole cardiac cycle at 240 beats per minute.
For a horse that has a history of bleeding and happens to be already functioning at a very marginal level, even minor disturbances in heart rhythm might therefore have an impact. Horses with airway disease or upper airway obstructions, such as roarers, might find themselves in a similar position. An animal that has not bled previously might bleed a little, one that has a history of bleeding may start again, or a chronic bleeder may worsen.
Relatively minor disturbances in cardiac function, therefore, might contribute to or even cause EIPH. If a horse is in relatively tough company or runs a hard race, this may also contribute to the onset or worsening of problems. Simply put, it's never a level playing field if you are running on the edge.
Severe bleeding
It has been suspected for many years that cases of horses dying suddenly at exercise represent sudden-onset cardiac dysfunction—most likely a rhythm disturbance. If the rhythm is disturbed, the closely linked and carefully orchestrated sequence of events that leads to filling of the left ventricle is also disturbed. A disturbance in cardiac electrical conduction would have a similar effect, such as one causing the two sides of the heart to fall out of step, even though the rhythm of the heart may seem normal.
The cases of horses that bleed profusely at exercise and even those that die suddenly without any post-mortem findings can be seen to follow naturally from this chain of events. If the changes in heart rhythm or conduction are sufficient, in some cases to cause massive pulmonary haemorrhage, they may be sufficient in other cases to cause collapse and death even before the horse has time to exhibit epistaxis or even clear evidence of bleeding into the lungs.
EIPH and dying suddenly
If these events are (sometimes) related, why is it that some horses that die of pulmonary haemorrhage with epistaxis do not show evidence of chronic EIPH? This is one of those $40,000 questions. It could be that young horses have had limited opportunity to develop chronic EIPH; it may be that we are wrong and the conditions are entirely unrelated. But it seems more likely that in these cases, the rhythm or conduction disturbance was sufficiently severe and/or rapid in onset to cause a precipitous fall in blood pressure with the animal passing out and dying rapidly.
In this interpretation of events, the missing link is the heart. There is no finite cutoff at which a case ceases to be EIPH and becomes pulmonary haemorrhage. Similarly, there is no distinct point at which any case ceases to be severe EIPH and becomes EAFPH (exercise-associated fatal pulmonary haemorrhage). In truth, there may simply be gradation obscured somewhat by variable definitions and examination protocols and interpretations.
The timing of death
It seems from the above that death should most likely take place during work, and it often does, but not always. It may occur at rest, after exercise. Death ought to occur more often in racing, but it doesn't.
The intensity of effort is only one factor in this hypothesis of acute cardiac or pump failure. We also have to consider factors such as when rhythm disturbances are most likely to occur (during recovery is a favourite time) and death during training is more often a problem than during a race.
A somewhat hidden ingredient in this equation is possibly the animal's level of emotional arousal, which is known to be a risk factor in humans for similar disturbances. There is evidence that emotions/psychological factors might be much more important in horses than previously considered. Going out for a workout might be more stimulating for a racehorse than a race because before a race, there is much more buildup and the horse has more time to adequately warm up psychologically. And then, of course, temperament also needs to be considered. These are yet further reasons that we have a great deal to learn.
Our strategy at the University of Guelph
These problems are something we cannot afford to tolerate, for numerous reasons—from perspectives of welfare and public perception to rider safety and economics. Our aim is to increase our understanding of cardiac contributions by identifying sensitive markers that will enable us to say with confidence whether cardiac dysfunction—basically transient or complete heart failure—has played a role in acute events.
We are also looking for evidence of compromised cardiac function in all horses, from those that appear normal and perform well, through those that experience haemorrhage, to those that die suddenly without apparent cause. Our hope is that we can not only identify horses at risk, but also focus further work on the role of the heart as well as the significance of specific mechanisms. And we hope to better understand possible cardiac contributions to EIPH in the process. This will involve digging deeply into some aspects of cellular function in the heart muscle, the myocardium of the horse, as well as studying ECG features that may provide insight and direction.
Fundraising is underway to generate seed money for matching fund proposals, and grant applications are in preparation for specific, targeted investigations. Our studies complement those being carried out in numerous, different centres around the world and hopefully will fill in further pieces of the puzzle. This is, indeed, a huge jigsaw, but we are proceeding on the basis that you can eat an elephant if you're prepared to process one bite at a time.
How can you help? Funding is an eternal issue. For all the money that is invested in horses there is a surprisingly limited contribution made to research and development—something that is a mainstay of virtually every other industry; and this is an industry.
Look carefully at the opportunities for you to make a contribution to research in your area. Consider supporting studies by making your experience, expertise and horses available for data collection and minimally invasive procedures such as blood sampling.
Connect with the researchers in your area and find out how you can help. Watch your horses closely and contemplate what they might be telling you—it's easy to start believing in ourselves and to stop asking questions. Keep meticulous records of events involving horses in your care— you never know when you may come across something highly significant. And work with researchers (which often includes track practitioners) to make your data available for study.
Remember that veterinarians and university faculty are bound by rules of confidentiality, which means what you tell them should never be ascribed to you or your horses and will only be used without any attribution, anonymously. And when researchers reach out to you to tell you what they have found and to get your reactions, consider actually attending the sessions and participating in the discussion; we can all benefit—especially the ultimate beneficiary which should be the horse. We all have lots to learn from each other, and finding answers to our many challenges is going to have to be a joint venture.
Finally, this article has been written for anybody involved in racing to understand, but covering material such as this for a broad audience is challenging. So, if there are still pieces that you find obscure, reach out for help in interpretation. The answers may be closer than you think!
Oyster
And what about Oyster? Her career was short. Perhaps, had we known precisely what was going on, we might have been able to treat her, or at least withdraw her from racing and avoid a death during work with all the associated dangers—especially to the rider and the associated welfare concerns.
Had we had the tools, we might have been able to confirm that whatever the underlying cause, she had cardiac problems and was perhaps predisposed to an early death during work. With all the other studies going on, and knowing the issue was cardiac, we might have been able to target her assessment to identify specific issues known to predispose.
In the future, greater insight and understanding might allow us to breed away from these issues and to better understand how we might accommodate individual variation among horses in our approaches to selection, preparation and competition. There might be a lot of Oysters out there!
For further information about the work being undertaken by the University of Guelph
Contact - Peter W. Physick-Sheard, BVSc, FRCVS.
Professor Emeritus, Ontario Veterinary College, University of Guelph - pphysick@uoguelph.ca
Research collaborators - Dr Glen Pyle, Professor, Department of Biomedical Sciences, University of Guelph - gpyle@uoguelph.ca
Dr Amanda Avison, PhD Candidate, Department of Biomedical Sciences, University of Guelph. ajowett@uoguelph.ca
References
Caswell, J.I. and Williams K.J. (2015), Respiratory System, In ed. Maxie, M. Grant, 3 vols., 6th edn., Jubb, Kennedy and Palmer’s Pathology of Domestic Animals, 2; London: Elsevier Health Sciences, 490-91.
Hinchcliff, KW, et al. (2015), Exercise induced pulmonary hemorrhage in horses: American College of Veterinary Internal Medicine consensus statement, J Vet Intern Med, 29 (3), 743-58.
Rocchigiani, G, et al. (2022), Pulmonary bleeding in racehorses: A gross, histologic, and ultrastructural comparison of exercise-induced pulmonary hemorrhage and exercise-associated fatal pulmonary hemorrhage, Vet Pathol, 16:3009858221117859. doi: 10.1177/03009858221117859. Online ahead of print.
Manohar, M. and T. E. Goetz (1999), Pulmonary vascular resistance of horses decreases with moderate exercise and remains unchanged as workload is increased to maximal exercise, Equine Vet. J., (Suppl.30), 117-21.
Vitalie, Faoro (2019), Pulmonary Vascular Reserve and Aerobic Exercise Capacity, in Interventional Pulmonology and Pulmonary Hypertension, Kevin, Forton (ed.), (Rijeka: IntechOpen), Ch. 5, 59-69.
Manohar, M. and T. E. Goetz (1999), Pulmonary vascular resistance of horses decreases with moderate exercise and remains unchanged as workload is increased to maximal exercise, Equine Vet. J., (Suppl.30), 117-21.
Can nutrition influence EIPH? -Catherine Rudenko investigates alternative and supportive therapies as trainers seek to find other means of reducing the risk or severity of EIPH
By Catherine Rudenko
EIPH (exercise-induced pulmonary haemorrhage) was first identified in racehorses in the 16th century. Since this time, the focus has been on mitigating the haemorrhage. Management of EIPH largely revolves around the use of furosemide, dependent of jurisdiction, may or may not be used on the day of racing. Alternative and supportive therapies are becoming increasingly popular as trainers seek to find other means of reducing the risk or severity of EIPH.
Nutrition and plant-based approaches are part of an alternative management program. Whilst research is somewhat limited, the studies available are promising, and no doubt more work will be done as using furosemide becomes more restricted. There are several directions in which nutrition can influence risk for EIPH, including inflammatory response, blood coagulation, cell membrane structure, hypotension and reducing known lung irritants.
Exercise- induced injury may exacerbate the severity of EIPH as a result of the delayed sealing of damaged micro vessels.
The various approaches are all supportive, working on altering an element of risk associated with the condition. Some are more direct than others, focusing on the effect on red blood cells, whilst others work on some of the broader lung health issues such as reducing mucus or environmental irritants.
None are competitive with each other, and there may be an advantage to a ‘cocktail’ approach where more than one mode of action is employed. This is a common practice with herbal-based supplements where the interactive effects between herbs are known to improve efficacy.
Cell membrane
The red blood cell membrane—the semipermeable layer surrounding the cell—is made up of lipids and proteins. The makeup of this membrane, particularly the lipid fraction, appears to be modifiable in response to dietary fatty acids. Researchers feeding 50mls of fish oil found a significant increase in the percentage of omega-3’s in the cell membrane.
Essential fatty acids (EFA’s), omega 3 and omega 6, are important cell membrane components and determine cellular membrane fluidity. Fluidity of a cell membrane is important, particularly when pressure increases, as a cell membrane lacking in fluidity is more likely to break. A cell that can deform, effectively changing rather than breaking, has an advantage and is linked with improved exercise performance in human studies. Inclusion of fish oil in the diet increases the ability of red blood cells to deform.
Kansas State University investigated the effect of omega supplementation on 10 thoroughbreds over a five-month period. The diet was supplemented with either EPA and DHA combined, or DHA on its own. EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are specific forms of omega-3 fatty acids commonly found in oily fish. When supplementing the diet with both EPA and DHA, a reduction in EIPH was seen at 83 days and again at 145 days. Feeding DHA on its own did not produce an effect.
Fish oil contains both EPA and DHA and is readily available, although the smell can be off-putting to both horse and human. There are flavoured fish oils specifically designed for use in horses that overcome the aroma challenge and have good palatability.
Inflammatory response and oxidative stress
Airway inflammation and the management of this inflammatory process is believed to be another pathway in which EIPH can be reduced. Omega-3 fatty acids are well evidenced for their effect in regulation of inflammation, and this mode of action along with effect on cell membrane fluidity is likely part of the positive result found by Kansas State University.
Kentucky Equine Research has investigated the effect of a specific fish oil on inflammatory response with horses in training. The study supplemented test horses with 60mls per day and found a significant effect on level of inflammation and GGT (serum gamma-glutamyl transferase). GGT is an enzyme that breaks down glutathione, an important antioxidant. As GGT rises, less glutathione is available to neutralise damaging free radicals, creating an environment for oxidative stress.
Kentucky Equine research results
A horse’s red blood cells are more susceptible to oxidative stress than humans, and maintaining a healthy antioxidant status is important for function and maintenance of cell integrity.
Rosehip
Supplements for bleeders will often contain relatively high doses of antioxidants such as vitamin C and vitamin E to support antioxidant status in the horse and reduce risk of damage to cell membranes. Vitamin C has also been shown to benefit horses with recurrent airway obstruction and increase antibody response. Dose rates required for an effect range from 15-20g per day. If including high doses of vitamin C in the diet, it is important to note that any sudden withdrawal can have negative effects. Gradual withdrawal is needed to allow the body’s own mechanisms for vitamin C production to recognise and respond to the change in status.
Rosehips are natural potent antioxidants containing many active substances. Research into the effect of rosehips specifically on red blood cells has shown they have a high efficacy when assessing their ability to ameliorate cell damage.
Hypotensive herbs
Caucus carota – wild carrott
The essential oil of caucus carota species is a well-documented oil having a hypotensive, lowering of blood pressure effect along with antifungal properties. Its antifungal effects are noted against aspergillus species, a common cause of poor respiratory health. Allium sativum is also well known for its ability to lower blood pressure. An initial study (data unpublished) into the effects of these two plants along with herbs reported to alleviate mucus in the lungs has shown promising results in a group of horses in training.
Prolonged blood coagulation
As prolonged blood coagulation is cited as a possible factor for EIPH, herbal products that are noted for their ability to enhance coagulation are in certain parts of the world widely used as part of managing EIPH. …
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Bleeders - the facts, fiction and future direction
By Dr. David Marlin
We are now approaching half a century since Bob Cook pioneered the use of the flexible fibreoptic endoscope, which allowed examination of the respiratory tract in the conscious horse. One of the important outcomes of this technique was that it opened the door to the study of ‘bleeding’ or exercise-induced pulmonary haemorrhage (EIPH). But nearly 50 years on the irony is perhaps that whilst we have become good at describing the prevalence of EIPH and some of the factors that appear to increase the severity of EIPH within individual horses, we still lack a clear understanding of the condition and how to manage it. I use the term manage rather than treat or prevent as our knowledge of EIPH must show us that EIPH cannot be stopped entirely; it is a consequence of intense exercise. The other irony is that in the past 50 years, by far the majority of research into the management of EIPH has focussed on the use of the diuretic furosemide. Whilst we have good evidence from controlled studies that furosemide reduces the severity of EIPH on a single occasion, we still lack good evidence to suggest that furosemide is effective when used repeatedly during training and or racing; and there is also evidence to the contrary.
Let’s review some basic facts about EIPH, which should not be contentious.
EIPH is the appearance of blood in the airways associated with exercise.
EIPH occurs as a result of moderate to intense exercise. In fact, EIPH has been found after trotting when deep lung wash (bronchoalveolar lavage or BAL) is done after exercise.
EIPH most often involves the smallest blood vessels (capillaries) but can sometimes and less commonly be due to the rupture of larger blood vessels.
The smallest blood vessels are extremely thin. Around 1/100th the thickness of a human hair. But this extremely thin membrane is also what allows racehorses such as thoroughbreds, standardbreds and Arabs to use oxygen at such a high rate and is a major reason for their athleticism.
EIPH is a progressive condition. The chance of seeing blood in the trachea after exercise increases with time in racing.
EIPH is variable over time, even when horses are scoped after the same type of work.
If you ‘scope a horse after three gallops in a row, you can expect to see blood in the trachea on at least one occasion.
EIPH damage to the lungs starts at the back and top, and over time moves forward and down and is approximately symmetrical.
Following EIPH the lung becomes fibrotic (as scar tissue), stiffer and does not work as well. The iron from the blood is combined with protein and stored permanently in the lung tissue where it can cause inflammation.
High blood pressure within the lung is a contributing factor in EIPH. Horses with higher blood pressure appear to suffer worse EIPH.
There is also evidence that upper airway resistance and breathing pattern can play a role in EIPH.
Airway inflammation and poor air quality may increase the severity of EIPH within individual horses.
Increasing severity of EIPH appears to have an increasing negative effect on performance.
Visible bleeding (epistaxis) has a very clear and marked negative effect on performance.
In order to make progress in the management of EIPH (i.e., to minimise the severity of EIPH in each individual), there are certain steps that trainers can take based on the information we have to date.
These include:
Ensuring good air quality in stables
Regular respiratory examination and treatment of airway inflammation
Reduced intensity of training during periods of treatment for moderate to severe airway inflammation
Extended periods of rest and light work with a slower return to work for horses following viral infection
Addressing anything that increases upper airway resistance (e.g., roaring, gurgling)
Avoiding intense work in cold weather
Avoiding extremes of going
Limiting number of training days in race preparation and increasing interval between races
Endoscopy
FUTURE OPPORTUNITIES IN UNDERSTANDING AND MANAGING EIPH
We have to accept EIPH as a normal consequence of intense exercise in horses. Our aim should be to reduce the severity to a minimum in each individual horse. However, there are areas in which we still need a much greater scientific understanding.
What actually causes the capillaries to leak or rupture?…
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EIPH: An Australian Perspective with Worldwide Implications
By Ellie Crispe and Guy Lester
Exercise-induced pulmonary haemorrhage (EIPH) is a common disease of racehorses. The precise cause of EIPH is yet to be fully determined, but a well-accepted theory is that lung blood vessels rupture in response to the extremely high blood pressure and low airway pressure experienced during strenuous exercise. The barrier that separates the airway from the blood vessels is ultra-thin to facilitate the efficient exchange of gases, but this predisposes to breakage. The condition is most frequently described in Thoroughbred and Standardbred racehorses, but it has also been identified in racing Appaloosas and Quarter Horses, as well as horses involved in other high intensity athletic activities, including showjumpers, 3-day eventers, barrel racers, steeplechasers and polo horses.
EIPH is not unique to horses and has been reported in human athletes, as well as racing greyhounds and camels. Our group at Murdoch University in Perth Australia has had an interest in EIPH, which has led to three recent publications in the Equine Veterinary Journal.1-3
How common is EIPH?
Blood from both nostrils—also known as epistaxis—is the most obvious manifestation of EIPH and occurs between 1.5 and 8.4/1000 race starts, varying with racing jurisdiction. Epistaxis represents a severe manifestation of EIPH, and basing surveys on its presence vastly underestimates the true prevalence of lung haemorrhage. There are several techniques used to diagnose EIPH, but endoscopy of the trachea 30-120 minutes after racing or galloping is a common and reliable method. Occurrence and severity of pulmonary haemorrhage is typically graded using a 0-4 scale. Using endoscopy, we reported a prevalence of EIPH post-race in Australian thoroughbreds racing on turf tracks of around 55%, with most positive horses having low to moderate volumes of blood in the trachea. EIPH is less common if horses are examined after trialling, and reduced further if examined after track gallops. The prevalence of EIPH increases when horses are examined on multiple occasions after racing, and in fact all horses in our research population that had seven monitored race-starts experienced EIPH on at least one occasion.
What is the effect of EIPH on race-day performance?
It is generally considered that EIPH has a negative impact on racing performance, but evidence for this assertion is surprisingly lacking. We performed 3,794 post-race endoscopy exams on over 1,500 Australian horses and reported that inferior race-day performance was limited to horses with severe EIPH (grades 3 and 4); this reflected only 6.3% of all examinations. Horses with the highest grades of EIPH (grade 4) were less likely to finish in the first three, finished further from the winner, were less likely to collect race earnings, were slower over the final stages of the race, and were more likely to be overtaken by other competitors in the home straight than horses without EIPH. Interestingly, horses with EIPH grade 1 or 2 were more likely to overtake others in the home straight, compared to horses without EIPH (grade 0).
It is highly unlikely that low-grade EIPH (grade 1 or 2) confers an athletic advantage; a plausible explanation is that horses that are ridden competitively to the finish are functioning at their maximal physiological limit, compared to horses that are eased up, and overtaken, during the finishing stages of the race because they are not in prize contention or are affected by interference in the home straight. Another interesting finding was that horses with moderate to severe EIPH (grades 3 or 4) raced the early and mid-sections of the race faster than horses without EIPH. It is possible that these horses reach the breaking threshold of the small lung blood vessels at an earlier stage in the race compared to horses that start the race slower, compounding the severity thereafter. A study of barrel racing horses reported that horses with the most severe grade of EIPH were faster than horses without EIPH, a finding which may also reflect this rapid acceleration increasing the risk of EIPH. It may be wise for trainers to instruct jockeys riding horses with a history of moderate to severe EIPH to refrain from racing in this manner.
What is the effect of a one-off diagnosis of EIPH over a horse’s career?…
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Is EIPH beyond the scope of dietary change?
Published in European Trainer - October - December 2017, issue 59.
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Exercise induced pulmonary haemorrhage has been a concern to trainers for a very long time. The historic record of EIPH in horses such as ‘Bleeding Childers’, a son of the Darley Arabian, a founder of the modern thoroughbred, shows that ‘bleeding’ as it is commonly known is an age-old problem.
The prevalence of EIPH during high intensity exercise, such as racing, is relatively high, but influenced greatly by how it is diagnosed. For example, the prevalence of EIPH is quite low when the appearance of blood from the nostrils (epistaxis) is used as the diagnostic criteria. Unsurprisingly, it is much higher when more rigorous investigative techniques such as endoscopy or bronchioalveolar lavage are used. Additionally, the prevalence increases when horses are repeatedly examined. In clinical terms, it has been suggested that if you look hard enough diagnostically, and often enough, almost all horses will show a degree of EIPH with racing at some time. A large Australian study has also reported that there is a proven heritability or genetic element to this condition.
Notwithstanding this, EIPH presents a major concern for horses in training, as it often leads to loss in training days and may impact on race performance, although this seems to be dependent on the degree or grade of EIPH involved. A period of absence from the racecourse can also be a requirement of some racing jurisdictions, e.g. the British Horseracing Authority in the UK, following epistaxis, where blood is seen visually from one or both nostrils. Public perception is also relevant, especially when the public mood puts racing under tighter scrutiny in terms of animal welfare.
There is also a mood for change with regards to the previously widespread use of pre-race medications such as furosemide (which has been widely used to treat EIPH) in countries such as the USA. The HH Sheikh Mansoor Bin Zayed Al Nahyan Global Arabian Horse Flat Racing Festival had recently announced that its races in the US will be ‘lasix-free’, which has been widely welcomed by trainers worldwide.
In some racing jurisdictions, nasal strips can be used which support the tissues of the nasal cavity helping to keep the upper airway fully open during exercise.
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Exercise induced pulmonary haemorrhage – a progressive disease affecting performance?
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Nasal Strips - increasing performance, reducing EIPH
Bill Heller (01 July 2007 - Issue Number: 4)
By Bill Heller
Nasal strips’ future in Thoroughbred racing seemed limitless in the fall of 1999. Just two weeks after longshot Burrito won a race at Keeneland wearing one, 29 of the 101 horses competing in the 1999 Breeders’ Cup at Gulfstream Park November 6th had the 4-by-6-inch strip affixed 1.5 inches above their nostrils.
More importantly, three of the eight winners wore them, including Cat Thief, who captured the $4 million Classic at odds of 19-1 under Pat Day, who was sporting a human equivalent, himself. The image of both Cat Thief and Day posing in the winner’s circle with nasal strips was a powerful one. Cat Thief’s victory was the second that day for Hall of Fame trainer D. Wayne Lukas, who earlier saddled 32-1 longshot Cash Run to win the $1 million Breeder’s Cup Two-Year-Old Juvenile Fillies. She, too, wore the non-invasive strip designed to reduce an exercising horse’s airway resistance and decrease exercise-induced, pulmonary hemorrhaging (EIPH).
The nasal strips received enormous national publicity after the Breeders’ Cup. Wouldn’t almost everyone in North America emulate Lukas? Stan Bergstein, the executive vice-president of Harness Tracks of America and a columnist for the Daily Racing Form, postulated long ago that if a horse wearing a blue balloon tied to his tail won a race, you’d see dozens of horses with blue balloons tied to their tails in the paddock the next day.
Lukas, however, preached caution regarding the role of nasal strips in Cash Run and Cat Thief’s surprise Breeders’ Cup victories. Regard-less, Lukas and trainer Bob Baffert spoke at a meeting of the California Horse Racing Board Medication Committee meeting, January 12th, 2000, in support of nasal strips. According to a CHRB press release, CHRB Commissioner Marie Moretti expressed hope that using the strips could lead to the decreased use of bleeder medication for some racehorses. That never happened, as Lukas proved prophetic. He saddled three horses in the 2000 Kentucky Derby, two with nasal strips, and none of them finished higher than 12th.
According to Equibase, between October 23rd, 1999, and April 24th, 2000, 8,402 Thoroughbreds wore the strip and 1,077 won, nearly 13 percent. Apparently that wasn’t high enough. Less and less trainers used them, though Lukas still does.
By the end of 2000, there was a story on the Internet site www.suite101.comentitled “The Demise of Nasal Strips.” Published December 12th, 2000, the article began, “The rise and fall of nasal strips was short and sweet.” Noting that the Daily Racing Form had originally listed the nasal strip in past performance lines for all tracks and that by mid-June was only listing them at Hollywood Park, the story concluded, “As quick as they appeared in the spotlight, they vanished.” The obituary was more than a bit premature.
Miesque’s Approval won the 2006 Breeders’ Cup Mile at Churchill Downs wearing a nasal strip for trainer Marty Wolfson, who uses them on all of his 30 horses. “I’ve been using them on all my horses for two years,” Wolfson said in mid-March. “I use them on myself. I run and they help me when I run. I breathe easier. The only time I couldn’t use one was when Pomeroy was in the 2006 Forego Handicap at Saratoga.” Pomeroy won that stakes. He was denied the nasal strip at Saratoga because the New York Racing Association mysteriously banned nasal strips, a day after the New York State Racing and Wagering Board approved them for both Thoroughbred and harness racing.
Currently, New Jersey is the only other state which doesn’t allow them, while Pennsylvania allows them for Thoroughbreds but not for Standardbreds.
According to nasal strip co-inventor and president of Flair Nasal Strips Jim Chiapetta, some 15,000 nasal strips are sold world-wide each year: 9,000 in the United States, 3,500 in Europe, 2,000 in Australia and New Zealand and 500 in Dubai. He said they were used mostly on horses in eventing, then on Thoroughbreds, Standardbreds and Quarter Horses.
Should they be used more often? Are they a realistic alternative to the powerful diuretic Lasix, which is now used by roughly 95 percent of all Thoroughbreds in the U.S., though the rest of the horse racing world bans Lasix and all other race-day medications? Lasix, which is used ostensibly to reduce EIPH, can improve a horse’s performance dramatically the first and/or second time it is used, if for no other reason that its diuretic properties. Horses can lose 10 to 20 pounds through urination after Lasix is injected. That alone improves most horses’ performance. Think about it. If there is an apprentice jockey with even a modicum of ability, trainers scramble for his services just to decrease the weight his horse is carrying by five pounds.
The efficacy of nasal strips can be judged in comparison to Lasix or by itself. “Lasix and nasal strips work in very similar ways,” said David Marlin, a consultant who worked for the Animal Health Trust in Newmarket, England, and co-authored Equine Exercise Physiology. “From scientific studies, they seem to be equally effective in reducing bleeding.”
Breathe Right strips were invented in 1987 by Bruce Johnson, who suffered from allergies. By the early 1990’s, they were being used for colds, allergies, snoring and athletic performance. They work by reducing the partial collapse of the soft tissues of the nose when it is under pressure because of the vacuum caused by the lungs during exercise. The mechanical, spring device maintains optimum air flow. Humans have an option for breathing: nose or mouth. Horses do not. They breathe only through their nostrils. Could nasal strips benefit horses?
That’s a question Jim Chiapetta and his partner Ed Blach decided to explore. They had become friends at the Littleton Large Animal Clinic in Littleton, Colorado.
Chiapetta, 48, returned to his clinic in Shakopee, Minnesota, to finish law school at William Mitchell College of Law. Blach, a former veterinarian who is now an animal products consultant, called Chiapetta in 1996 to discuss a possible equine version of a nasal strip.
“We talked to a bunch of people and they said it wouldn’t work for horses, but I told Ed I think it could,” Chiapetta said. “We went ahead and made some prototypes.”
Then they consulted Monty Roberts, the horse whisperer. “Ed used to be Monty’s resident veterinarian,” Chiapetta explained. Roberts was interested enough to have them test the strip at a track at Roberts’ farm north of Santa Barbara in California. “We didn’t have the adhesive done right,”
Chiapetta said. “The riders were coming back and saying, `This horse felt better, more relaxed.’ So we figured there was something there.”
Having breakfast one morning with Roberts, Chiapetta and Bloch came up with a name. “I was thinking about flaring nostrils, then I was thinking about air, and we came up with the name Flair,” Chiapetta said.
Next, they consulted with CNS, the Minnesota company which manufactured Breathe Right. “They agreed to license it if it showed it reduces bleeding,” Chiapetta said. “They funded a study at Kansas State University.”
That study and a majority, but not all, of a handful of subsequent studies - all involving a standard small sample of horses - showed positive results from nasal strips. “The nasal strips seem to help,” Dr. Howard Erickson of Kansas State University, a co-author of one of the studies, said last February. “We’ve done studies here. There have been studies in Kentucky, California and Florida. In most of the studies, it decreases the bleeding by 50 percent and it also decreases the airway resistance.”
He believes that most horses would benefit from both, because he believes almost all horses suffer from EIPH: “I think it’s nearly 100 percent that have some degree of bleeding for the movement of fluid from the capillaries to the airway. For some, it may be negligible. Quarter Horses will respond the same way. Standardbreds, too. You see it in rodeo horses and barrel horses.”
That sentiment is shared by David Marlin, who has worked with researchers at Kansas State. “The bottom line is that all horses will break blood vessels in a race,” he said. “It happens with camels; it happens with humans, it happens with greyhounds.”
Marlin also believes that nasal strips may be a more preferable treatment than Lasix. “It’s less complicated and you can’t build up tolerance,” he said. “If you think about a diabetic who uses insulin, he develops tolerance and needs more of it. Do horses develop tolerance of Lasix? Generally, when you use drugs repeatedly, there’s a chance of adaptation to it. The nasal strip is different because it’s a mechanical device.”
Then why aren’t trainers around the world, and especially in the United States, using them?
Ironically, Chiapetta believes that the success of Cash Run and Cat Thief in the 1999 Breeders’ Cup is a major reason why. “It was the worst possible thing that could have happened,” he said. “We were on the front page of the New York Times Sports Section, the Wall Street Journal and Sports Illustrated. I think horsemen said, `Hey, this will make us win.’ So they strapped them on. And when they didn’t win, they took them off.”
Some, not all.
“They’re expensive ($7.95 per strip),” Wolfson said. “Some people don’t want to spend the money, but I think it’s worth it.”
Day, the retired Hall of Fame jockey, knew they worked on him. “I found them to be quite helpful when I was riding a number of races back to back,” he said. “It seemed that I was less fatigued because I believed I was getting much more air into my lungs. I would have thought that would be more helpful to horses than riders. Horses only breathe through their noses. They cannot or will not breathe through their mouths. If you can open up the nasal passages, open the airways, you would think it would be beneficial to the horses.”
At the Havemeyer Foundation Workshop investigating EIPH, March 9th-12th, 2006, in Vancouver, Canada, Dr. Frederick Derksen, of the Department of Large Animal Clinical Sciences at Michigan State University, spoke about the role of airways in EIPH. He said, “A series of studies demonstrated that the use of a nasal strip decreases the number of red cells in bronchoalveolar laverage fluid after exercise. In horses, the majority of inspiratory resistance to airflow is located in the upper airway. The nasal valge region, located just cranial to the nasoincisive notch is a high resistance region, not supported by bone or cartilage. These characteristics make this region particularly susceptible to collapse during inhalation. Application of the nasal strip in this region prevents nasal collapse and decreases upper airway resistance during exercise. This in turn is expected to reduce negative alveolar pressure during inhalation and decrease transmural capillary pressures.”
The nasal strips are certainly a hit in New Zealand, especially with harness horses. After reading about the use of nasal strips in the 1999 Breeders’ Cup, Brian McMath, a committee member of the New Zealand Standardbred Breeders Association, imported a few samples. After the strips were approved by Harness Racing New Zealand, several trainers began using them and many had success, including Jim and Susan Wakefield’s Glacier Bay, who won the $105,000 PGG Sales Series Final at Alexandria Park in April, 2000, for trainer Cran Daigety. Eventually, Thoroughbred trainers began using the strip, too. By the end of 2004, more than 700 winners in both harness and Thoroughbred racing won wearing the strip.
“I have a technology background in chemistry and engineering, and what convinced me the strips work was basic physics,” McMath said. “It’s all about windpipe pressures and how a simple mechanical device like the springs in the nasal strip can beneficially alter these pressures.”
The reception in Europe, at least for Thoroughbreds, was decidedly cooler. In an April 11th, 2000, letter, Peter Webbon, the Chief Veterinary Adviser to the British Jockey Club, noted that the senior veterinary surgeons from the European Horserace Scientific Liaison Committee (Britain, France, Italy, Germany) considered the question of nasal strips and decided to recommend to their racing authorities that their use should be banned for the following reasons:
1 “Other `gadgets’, such as tongue ties, which are allowed, are intended to address a specific clinical entity. Nasal strips are seen by trainers as a non-specific way of improving performances.
2 “If they improve performance, they should be banned, in line with performance enhancing medication.
3 “If they are ineffective, they should be banned because they give the impression that we condone practices that are intended to improve performance.
4 The manufacturers claim that they reduce the frequency/severity of EIPH. The EHSLC veterinarians felt very strongly, for the sake of the breed, that horses should run on their merits. What would be the effect on the Thoroughbred in the long term if a horse won the Derby, wearing a nasal strip,that without the strip was unable to win a selling race?”
To this day, they are banned throughout Europe for racing but allowed for training.
Two years ago, Chiapetta met with Webbon and his assistant in Newmarket. “He said, `It reduces fatigue, which improves performance,’” Chiapetta related. “I said, `If you shoe them, do they run better? If you feed them, do they run better? If you train them, do they perform better? Where do you draw the line?’”
Event horses are allowed to use them throughout the world because they were approved by the International Federation for Equine Sports (FEI).On June 26th, 2006, Horse & Hound wrote that nasal strips “are becoming commonplace on the noses of top event horses,” and noted that Andrew Hoy’s Moon Fleet won the Badminton, a premier cross-country event in England. “I started using them two years ago,” Andrew Hoy said. “I’d seen them being used on horses and humans, and discussed their use with a vet. I had used a human one myself when I had a cold, and it seemed to help. I now use them on my horses at top events to give them every opportunity.”
The story said that another eventer, Francis Whittington, uses them on his “advanced” horse Spin Doctor. “I tried the human version and noted the difference,” he said. “I believe it makes it easier for him to breathe so he can last the distance.”
That’s the whole point. “Some people may think that more oxygen makes them run faster,” co-inventor Blach said. “That’s not the case. Rather, horses perform at their optimum level for a longer time so they can do what they’re made to do over the long haul. Maybe it’s too simple. It’s based on very simple physics that if you maintain the size of an opening, you’re going to maximize what goes through it, in this case air.”
Asked if nasal strips help horses, Blach said, “Absolutely.” Perhaps the most confounding question about nasal strips is that even the single negative clinical study about them said that they do not reduce EIPH, but offered no tangible downside to their usage. Asked if there is a downside, Marlin said, “I think, as far as anyone knows from a scientific point of view, there is no evidence that there is.” Referring to that study, Chiapetta said it showed that horses using them “certainly weren’t less healthier. I don’t think there’s any downside to it.”
Dr. Ted Hill, the New York Racing Association steward for the Jockey Club, said on April 11th, “Our only downside was how to regulate it. If a horse comes to the paddock and it falls off, what do we do? Do we treat it as equipment? We can’t put it back on. The significant problem we had originally was it possibly being an aid to bleeders, and relaying that to the public. That came up in an international meeting at a round table in Tokyo last October. It did not receive wide acceptance because it has some efficacy.” So Japan does not allow them. Australia allows them for Standardbreds, but not for thoroughbreds. Yet, nasal strips are allowed for Thoroughbreds in Dubai and Singapore, as well as New Zealand. “It’s probably been embraced more in other countries than here, but in Thoroughbred racing here, furosemide (Lasix) is so embedded,” Kansas State’s Erickson said. “Furosemide reduces weight. It certainly reduces bleeding. But maybe we have to look for something better.” Maybe something better has been out there for eight years.
Inhalation therapy - treating airway problems in the racehorse
Physiologically speaking, one of the major limiting factors to racehorse performance is how efficiently the lungs can exchange gasses. Clearly any threat to the efficiency of the lungs will result in poor performance.
Paul Peacock (European Trainer - issue 14 - Summer 2006)
Physiologically speaking, one of the major limiting factors to racehorse performance is how efficiently the lungs can exchange gasses. Training maximises the potential of any athlete, equine or human, to continue functioning at full throttle while the metabolism changes to deal with an oxygen debt in the muscle tissues. Clearly any threat to the efficiency of the lungs will result in poor performance. Horses are subject to a wide range of respiratory diseases; heaves, lung bleeding or exercise- induced pulmonary haemorrhage (EIPH), and exercise induced Airway Inflammatory Disease (IAD) among them. Another description of the same basic problem is Chronic Obstructive Pulmonary Disease or (COPD). Like all mammals, horses suffer from allergic reactions as well as viral and bacterial infections. The epithelial linings of the airways and the lungs are sensitive to infection or foreign bodies of any size, and the result is usually a mucosal discharge which blocks the airway.
Whichever route an animal has airway problems, by infection or allergy, the result is almost the same; mucous builds up, coughing and irritation, frequent nose bleeding and considerably reduced performance. Moreover, some animals with tendencies towards heaves can show little signs of respiratory stress at times, but can be triggered later, more frequently by pollen and dust, when a change in regime occurs. The treatment options can be quite different for horses with a zootic infection to those with an allergy. Treatment of IAD involves the use of bronchial dilators and steroids, which have treatment implications of their own. Some of the drugs used can cause the gut to become sluggish, and can lead to colic.
Many of them induce tachycardia, the speeding of the heart rate, and still others make the animal skittish and nervous. Similarly, the use of corticosteroids in cases of allergic response, can affect the immune system, lead to numbers of other opportunistic infections, particularly in the mouth and have been implicated in laminitis. Bronchodilators include substances well known to human medicine and their function is to cause the dilation of the airways, thus allowing more air in and out of the lung. When irritated, the airways constrict and then produce mucous, which is then countered by the drug. There are two types of drug used for dilation of the airways, and they work very differently in the horse.
The Salbutamol type inhalation works on receptors on the epithelial cells of the airway, relaxing the muscle, thus causing dilation. They work at best for around an hour. A second class of drug, anticholinergics, work on various parts of the larger airway. Consequently, a mixture of the two types of drug is frequently used. Nigel Haizelden of the Ledston Equine Clinic in Castleford, West Yorkshire has been using this therapy for over 12 years and states that all kinds of drugs are administered using this system. Using a nebuliser, antibiotics, corticosteroids and bronchodilators are regularly applied. He points out that “the nebuliser is used to get the specific particle size which is required to reach a certain part of the lung – this is critical to the treatment.” Another important aspect of the bronchodilator is that the easier breathing allows the animal to relax under exercise, something which tends to promote further airway dilation. However, they do nothing for inflammation. Treatment should be associated with a regime which removes the animal from possible irritants. Trainer magazine has dealt with varying aspects in recent issues, from dust-free bedding to pollen allergy; particularly that produced by Oil Seed Rape.
One of the problems of treatment has included the fact that in order to get the drugs into the animal, the whole horse has to be treated. Injecting a horse with drugs means providing a high enough concentration in the animal’s blood which, when diluted by the circulatory system and metabolised by the liver, there is enough at the site of operation to do its work. Consequently a much higher concentration of drug is used than would be required if it could somehow be administered solely where it is needed and nowhere else. Inhalation therapy has been used in humans for a long time, from the vapour baths of Victorian days to modern viral carrier gene manipulation therapy proposed for such disorders as cystic fibrosis.
There are a number of benefits. Firstly the lung is an excellent way of getting a balanced concentration of drug into the blood stream. It works very quickly. In the case of airway disease, the drug is being used directly at the point that it is needed, and consequently the amount of drug required to be effective is greatly reduced. This improves treatment options by reducing the possibility of side effects. There are a couple of products on the market that allow this type of therapy. The Aeromask and the Equine-haler. Both are available via the vet and come from the United States. Their use has become increasingly widespread across Europe, particularly in France and Germany, where there have been particular links with American racing practices. IN the UK they have been used for at least fifteen years and the treatment regimes have developed accordingly. The Aeromask is strapped onto the head and the drug is held in a reservoir called the spacer. The Equine-haler is a cone which has to be held over the nose of the animal while the drugs are placed in a compartment at the bottom. This allows for a metered dose aerosol to deliver a dose to the spacer which is then inhaled by the horse. It only works on one nostril, and a puff of medicine is released into the nose.
The Equine-haler need not be held in position all the time, it allows for a puff of medicine to be fired into a spacer which then can be applied to the horse when it breathes in next time. Between the two it should be possible to find a regime which will ideally suit any animal, those shy of the head bag of the Aeromask could easily treated by the Equine-haler and visa versa according to the treatment required. It is important that only a measured amount of drug is administered, under veterinary control, so that overdoses do not occur. Similarly, the equipment should not be used to administer anything other than prescribed medicines. One yard on the continent was reported to have used their own remedies in association with the mask, which consequently caused some blistering to the horse’s mouth.
There are some risks associated with the use of inhalation therapy. One is associated with the drugs themselves. These drugs are particularly effective on the metabolism of the animal. It produces dilation of blood vessels, particularly in the liver, and it also promotes the production of insulin. In America at least, where there are different rules in various states regards doping, trainers are advised to take advice before racing. However, this method of treatment has meant that withdrawal periods for horses under treatment are considerably reduced in comparison to former treatments. Another possible problem is associated with the effect of the drug on the mouth, where fungal infections have been associated in humans with constant use.