Assessment of historical worldwide fracture & fatality rates and their implications for thoroughbred racing’s social licence

Article by Ian Wright MRCVS

Racing’s social licence is a major source of debate and is under increasing threat. The principal public concern is that racing exposes horses to significant risk of injury including catastrophic (life-ending) injuries of which fractures are the commonest cause. The most recent studies in the UK indicate that fractures account for approximately 75% of racecourse fatalities. Recent events highlight the need for urgent stakeholder discussion, which necessarily will be uncomfortable, in order to create cogent justification for the sport and reliant breeding industry.

A necessary prelude to discussion and debate is an objective assessment of risk. All and any steps to reduce risks and mitigate their impact are important and must be embraced by the horseracing industry (and quite possibly all other horse sports). To begin this, a here and now assessment is important: put simply, does the price paid (risk) justify the benefit (human pleasure, culture, financial gain, employment, tax revenue, etc). Objective data provides perspective for all interested parties and the voting public via their elected representatives, who ultimately provide social licence, with other welfare issues—both human and animal—on which society must pass judgement. 

The data in Tables 1 to 12 report a country by country survey of fracture and fatality rates reported in scientific journals and documented as injuries/fatalities per starters. It may be argued that little of the data is contemporary; the studies range from the years 1980 to 2013. However, the tabulated data provided below is the most up to date that can be sourced from independently published, scrutinised scientific papers with clear—albeit sometimes differing—metric definitions and assessable risk rates.

In assimilating and understanding the information, and in order to make comparisons, some explanatory points are important. The first, and probably the most important, is identification of the metric. Although at first glance, descriptor differences may appear nuanced, what is being recorded massively influences the data. 

These include fatality, catastrophic injury, fracture, orthopaedic injury, catastrophic distal limb fracture, fatal musculoskeletal injury, serious musculoskeletal injury, and catastrophic fracture. The influence of the metric in Japanese racing represents the most extreme example of this: ‘fracture’ in the reporting papers included everything from major injuries to fragments (chips) identified after racing in fetlocks and knees, i.e. injuries from which recovery to racing soundness is now an expectation.  At the opposite pole, studies in other countries document ‘catastrophic’, i.e. life-ending fractures which have a substantially lower incidence. The spectrum of metric definitions will all produce different injury numbers and must be taken into account when analysing and using the data. 

Studies also differ in the methods of data collection that will skew numbers in an undetermined manner. Some only record information available at the racecourse, others by identifying horses that fail to race again within varying time periods, horses requiring hospitalisation following racing, etc. The diagnostic criteria for inclusion of horses also vary between reports: some document officially reported incidents only, some are based only on clinical observations of racecourse veterinary surgeons, while others require radiographic corroboration of injuries. 

From a UK perspective, the data is quite robust in concluding that risks differ significantly between race types. The majority of fractures that occur in flat racing, and between obstacles in jump racing, are the result of stress or fatigue failure of bone. They are not associated with traumatic events, occur during high speed exercise, are site specific and have repeatable configurations. In large part these result from a horse’s unique athleticism: in the domesticated species, the thoroughbred racehorse represents the pinnacle of flight-based evolution. Fractures that result from falls in jump racing are monotonic—unpredictable, single-event injuries in which large forces are applied to bone(s) in an abnormal direction. 

This categorisation is complicated slightly as fatigue failure at one site, which may be bone or supportive soft tissue, can result in abnormal loads and therefore monotonic fracture at another. The increased fracture rate in jump racing is explained in part by cumulative risk. However, it is complicated by euthanasia of horses with injuries with greater post injury commercial value and/or breeding potential that might be treated. Catastrophic injuries and fatality rates in NH flat races are most logically explained by a combination of the economic skew seen in jump racing and compromise of musculoskeletal adaptation.

Racing surface influences both injury frequency and type. Studies in the UK have consistently documented an increased fatality rate and incidence of lower limb injury on synthetic (all weather) surfaces compared to turf.  Although risk differences are clear, confounding issues, such as horse quality and trainer demographic, mean that the surface per se may not be the explanation. In the United States, studies reporting data from the same geographic location have produced mixed results. In New York, these documented greater risks on dirt than turf surfaces; while a California study found no difference, and a study in Florida found a higher risk on turf. A more recent study gathering data from the whole of the U.S. reported an increased risk on dirt surfaces. Variations in the nature of injury between surfaces may go some way toward explaining fatality differences.

Much has been done to reduce recognisable risk factors particularly in jump racing; but in the UK, it is likely (for obvious data supported reasons) that it will come under the greatest scrutiny. The incidence of fractures and fatalities in flat racing are low, and the number of currently identified risk factors are high. Over 300 potential influences have been investigated, and over 50 individual factors demonstrated statistically are associated with increased risk of catastrophic injury. 

The majority of fractures occurring in flat racing (and non-fall related fractures in jump racing) are now also treatable, enabling horses to return to racing and/or to have other comfortable post-racing lives. 

The common public presumption that fractures in horses are inevitably life-ending injuries is a misconception that could readily be remedied. An indeterminate number of horses are euthanised on the basis of economic viability and/or ability to care for horses retired from racing. On this point, persistence with a paternalistic approach is a dangerous tactic in an educated society. Statements that euthanasia is ‘the kindest’ or ‘best’ thing to do, that it is an ‘unavoidable’ consequence of fracture or that only ‘horsemen understand or know what is best’ can be seen as patronising and will not stand public scrutiny. 

At some point, data to distinguish between horses euthanised as a result of genuinely irreparable injuries and those with fractures amenable to repair will become available. Before this point is reached, the consequences require discussion and debate within the racing industry.

Decisions on acceptable policies will have to be made and responsibility taken. In its simplest form, this is a binary decision. Either economic euthanasia of horses, as with agricultural animals, is considered and justified as an acceptable principle by the industry or a mechanism for financing treatment and lifetime care of injured horses who are unlikely to return to economic productivity will have to be identified.  The general public understands career-ending injuries in human athletes: These appear, albeit with ongoing development of sophisticated treatments at reducing frequency, in mainstream news. 

Death as a direct result of any sporting activity is a difficult concept in any situation and draws headlines. Removal of the treatable but economically non-viable group of injuries from data sets would reduce, albeit by a currently indeterminate number, the frequency of race course fatalities. However, saving horses' lives whenever possible will not solve the problem: it will simply open an ethical debate viz is it acceptable to save horses that will be lame? In order to preserve life, permanent lameness is considered acceptable in people and is not generally considered inhumane in pets. Two questions arise immediately: (i) How lame can a horse be in retirement for this to be considered humane? (ii) Who decides? There is unquestionably a spectrum of opinion, all of which is subjective and most of it personal. It will not be an easy debate and is likely to be complicated further by consideration of sentience, which now is enshrined in UK law (Animal Welfare (Sentience) Act 2022); but it requires honest ownership of principles and an agreed policy.

For the avoidance of doubt, while the focus of this article and welfare groups’ concerns are on racecourse injuries, those sustained in training follow a parallel pathway. These currently escape attention simply by being, for the most part, out of sight and/or publicity seeking glare. 

Within racing, there is unquestionably a collective desire to minimise injury rates. Progress has been made predominantly by identification of extrinsic (i.e. not related to the individual horse) risk factors followed by logical amendments. In jump racing (monotonic fractures), obstacle modification, re-siting and changing ground topography are obvious examples of risk-reducing measures that have been employed. 

In flat racing progress has involved identification risk factors such as race type and scheduling, surface, numbers of runners, track conditions etc which have guided changes. However, despite substantial research and investment, progress in identification of intrinsic (ie relating to the individual horse) risk factors is slow. While scientifically frustrating, a major reason for this is the low incidence of severe fractures: this dictates that the number of horses (race starters) that need to be studied in order to assess the impact of any intervention is (possibly impractically) high. Nonetheless, scientific justification is necessary to exclude a horse from racing and to withstand subsequent scrutiny.

Review of potential screening techniques to identify horses at increased risk of sustaining a fracture while racing is not within the scope of this article, but to date none are yet able, either individually or in combination, to provide a practical solution and/or sufficiently reliable information to make a short-term impact. It is also important to accept that the risk of horses sustaining fractures in racing can never be eliminated. Mitigation of impact is therefore critical. 

When fractures occur, it is imperative that horses are evaluated to be given the best possible on course care. This may, albeit uncommonly be euthanasia. Much more commonly, horses can be triaged on the course and appropriate support applied before they are moved to the racecourse clinical facility for considered evaluation and discussion. The provision of fracture support equipment to all British racecourses in 2022 marked a substantial step forward in optimising injured horse care.

Neither racing enthusiasts nor fervent objectors are likely to change their opinions. The preservation of social licence will be determined by the open-minded majority who lie between: it is the proverbial ‘man on the street’ who must be convinced. The task of all who appreciate horse racing's contributions to society and wish to see it continue is to remain focussed on horse welfare, if necessary to adjust historical dogmas, absorb necessary costs and to encourage open, considered, honest (factually correct) risks versus benefits discussion.

Treating 'bucked shins' in the thoroughbred racehorse

Article by Adam Jackson MRCVS 

One of the most common causes of lost days to training and racing in racehorses is dorsal metacarpal disease (DMD), which is often referred to as “bucked shins” or “sore shins”.  

Often a frustration to trainers and owners, this problem rears its ugly head at the time of highest expectations, such as arising the last day of work before a horse’s first race; right after a horse’s first victory; or after a horse was purchased at a two-year old sale.

This disease presents with heat, pain with or without inflammation (swelling) on the dorsal (front) surface or the dorsomedial (front inside) surface of the third metacarpal bone (cannon) referred to as acute periostitis. With rest and reduced exercise, the condition can improve, but catastrophic fractures of the cannon may occur at the site of previous DMD episodes.  A good understanding of this disease and strategies of prevention are vital in order to improve the welfare of the horse and reduce the potential expenses to all shareholders.  

Introduction

The cannon bone is an important structure in the weight-bearing and absorbing shock. As the horse moves, the bone bends a little and then returns to its original shape like an elastic band, often referred to as elastic deformation.  In addition, it has been observed that horses that work slowly have tension on the front of the cannon bone; in other words, the bone is stressed by a stretching force rather than a compressing force. However, at higher speeds, these forces change from stretching to compressing forces.

Repeated bending forces (stress cycle) on the cannon bone causes dorsal metatarsal disease. When the horse is young, it has a thin bone cortex. As the horse grows and is repeatedly subjected to these forces, the bones remodel and the cortex thickens, making it stronger. However, if the bending forces exceed the bone’s ability to remodel, then this leads to stress fatigue and bone damage.

The occurrence of bucked shins is most common when horses are developing, typically two–three years old as training becomes more intensive. But it must be noted that if the horse is not bone fit, any aged racehorse is susceptible to these diseases when they begin training. Roughly at the age of five years old when a horse is fit, they are at a low risk of this disease. Within the first six months of training, DMD may present in one or both front limbs. If the condition does occur in both front limbs and the horse is being trained on a circular track, then it is likely the inside leg is where it will occur first.  In other words, if the training tends to be in a counterclockwise training circuit, then there are greater forces on the left limb than the right; thus the left is more likely to develop the disease before the right limb.

Risk Factors of DMD

Age: DMD occurs most commonly in 2–3 year olds, often within their first 6 months of training. It is rarely seen in horses with a mature skeleton (age 4 and over). However, this disease has been seen in 5 year olds especially if they have been stalled for a long amount of time after weaning and not racing until that age.

Gender: It is believed that the gender of the horse does not alter its risk to DMD.

Breed: Most common in thoroughbreds but may be seen in both standardbreds and quarter horses. 

Genetics: The risk of DMD is influenced by genetics as variation in limb bone geometry (inherited) behaves differently to force/strains on the bone. In addition, the longer the cannon bone, the greater the load is at flexion of the dorsal cortex of the bone, making it more susceptible to DMD.

Training and racing surfaces: The different types of training and racing surface alter the risk to DMD because there are variations in the force applied to limbs as well as the acceleration rates of hoof impact.  Furthermore, the impact of these forces is increased with greater speed.  Dirt tracks tend to be the hardest surface, whereas synthetic tracks reduce hoof and limb impact and loading force.  However, it is important to remember that the hardness of all of these surfaces can be altered by a number of other factors such as:

1. Different surface materials

2. Changes in weather, temperature and humidity

3. Surface maintenance (i.e., soaking, harrowing)

4. Changes in horse body weight

5. Age of surface – wear and tear of surface

6. Human opinion of track’s condition

Training: The length of time for bones to respond to different training practices is unknown. Although further research is required, it is suggested that fast work should be avoided in the early stages of training as it is thought that high-speed exercise introduced too quickly (within 1 month) was detrimental to bone health.

Direction of training: Track direction varies globally. Thoroughbreds tend to lead with the inside forelimb around turns then switch to the outer forelimb on the straight. It has been suggested that due to greater forces on the leading limb on the turn, that limb is more at risk of bucked shins. However, more research is required to make accurate conclusions.

Speed: Current research is contradictory. Some research indicates a reduction in the risk of DMD if the horse is trained at high speeds with every extra mile worked and canter work increases the risk. However, other research suggests that short periods of work (< 1 month) at high speed increases the risk of DMD.

Camber:  European tracks, with turf being the prevalent surface, tend to vary in their design, often including slopes, twists, turns, uphill sections, and cambers. In addition, races may be run straight, clockwise or counterclockwise. This is in contrast to the USA where the tracks are usually flat. Although it is known that this variation in track characteristics alters the horse’s gait, thus altering forces on the forelimbs, further research is needed to understand if these variations increase the risk of DMD.

How does DMD develop?

Buck shin is the formation of tiny stress fractures on the front or inside of the cannon bone of the horse’s front legs. DMD occurs when the stress on the legs with high-speed training exceeds the bone’s ability to adapt to those stresses. 

Bone is a dynamic tissue that is constantly adapting its structure. Once the bone is formed in immature animals, the bone grows and changes shape by a process called modelling. Bone remodelling is different from modelling in that its function is to renew the skeleton and involves both bone resorption and formation to occur at the same location in a sequential manner.   

With high-speed training, there is high-strain fatigue, which causes excessive compression of the bone. During this compression, there is insufficient amount of bone remodelling at the point of stress. At this site, this new bone is much weaker; thus, it is susceptible to inflammation and pain and may lead to fractures.

Treatment of dorsal metacarpal disease

Treatment of DMD is designed to alleviate pain and inflammation while allowing the remodelling process of the bone to catch up with the damage that has been caused from stress cycling.

The core of the treatment is rest and providing pain relief, followed by a slow and gradual increase in exercise levels. 

Fractures of the bone cortex can be treated with surgery using lag screw fixation and osteostixis. Osteostixis is the drilling of many holes around the site of fracture in order to promote bone healing. Lag screw fixation is the drilling of a screw across the fracture line to compress and stabilise the bone. However, fracture recurrence is common with both techniques and requires 5–6 months out of training.

There are additional treatments that may be used to complement core treatments. Extracorporeal shock wave therapy (ESWT) is commonly used for treatment and involves a highly concentrated, powerful acoustic (sound) energy source being applied to the site of injury. The rationale is that ESWT increases blood flow, increases growth of new blood vessels and increases the production of natural healing factors in the treated area. The research findings are limited on its effectiveness but anecdotally amongst the veterinary profession, it seems to work on bucked shins and stress fractures. 

In Europe, horses must not have had shock wave therapy on the day of racing, or on any of the five days before the race day in which the horse is declared to run. In North America, horses are not permitted to race or breeze for 30 days following treatment as per the Horseracing Integrity and Safety Authority’s (HISA) rulings. 

With all treatment options, there must be a careful and considered discussion with the veterinarian and all stakeholders on the desired outcome while bearing in mind the important factor of the horse’s welfare and wellbeing.

What about bisphosphonates?

Some clinicians are using a combination of shockwave and bisphosphonates (Tildren TM, OsPhos, TM) to treat DMD. Bisphosphonates were first seen in human medicine and used for osteoporosis. Bones are constantly remodelling in a process that removes old bone cells and deposits new ones. Bisphosphonates help prevent bones from losing calcium and other minerals by slowing or stopping that natural process that dissolves bone tissue, thus, helping bones remain strong and intact. Veterinary surgeons report mixed results with these therapies, and long-term use of bisphosphonates is expensive and has serious consequences. Bisphosphonates are toxic to the gastrointestinal and renal systems, thus, potentially causing colic and kidney disease. Their safety has not been evaluated for the use in horses younger than four years old nor in pregnant and lactating mares.

RULES ARE CHANGING - Bisphosphonates

Bisphosphonates are not to be administered to a racehorse under the age of three years and six months as determined by its recorded date of birth, on the day of the race or on any of the 30 days before the day of the race in which the horse is declared to run as per The International Federation of Horseracing Authorities rulings for Europe. 

In America, HISA’s Anti-Doping and Medication Control (ADMC) Program came into effect on March 27 and with it, new regulations regarding the presence and use of bisphosphonates.

The Horseracing Integrity & Welfare Unit (HIWU) states “The ADMC Program regulations categorise bisphosphonates as a Banned Substance, meaning that they are prohibited from being administered to, or present in, covered horses at any time. Covered horses that test positive for bisphosphonates under the ADMC Program are subject to lifetime ineligibility, and associated covered persons may incur an Anti-Doping Rule Violation.”

“HIWU will not pursue disciplinary action against Covered Horses or their associated covered person(s) for the presence of bisphosphonates if the covered person(s) can provide documentation (e.g. medical records or a positive test result) to HIWU of the administration or presence of bisphosphonates prior to the implementation date of the ADMC Program.” 

Training regimens

With DMD, it must be remembered that it is an appropriate response for new bone formation when the cannon endures cyclic stress and injury. This injury cannot be ignored but addressed to reduce the risk of serious consequences.  Exercise is the root of the problem; therefore, the solution is to alter the patterns of exercise.   

Dr David Nunamaker DVM of the University of Pennsylvania has developed a training programme, which is believed to reduce the risk of DMD. The rationale when developing this modified training programme is that horses are not born with the right bone structure for racing. The bones are to develop and adapt to racing. By providing training programmes that mimic racing, the bones can adapt to the forces that are applied during racing, thus reducing the risk of developing bucked shins.

When initiating this training regimen, it is assumed that young horses are broken to ride in autumn and able to gallop a mile by January so that training can start. 

Stage 1 (5 week duration) – Horses finish the gallops two times a week with the last 1/8th of the mile (last 200 metres of 1600 metres) completed in an open gallop in 15 seconds.

Stage 2 (5 week duration) – Twice a week open gallops for ¼ of a mile (400 metres of 1600 metres) in 30 seconds, including a 1 mile (1600 metres) gallop.

Stage 3 (7 week duration) – The addition of speed work once per week.  Breezing (moderate speed) for ¼ mile (400 metres) and daily gallops lengthened to 1 ¼ miles twice per week for 4 weeks. The following 3 weeks, the ¼ mile breeze is continued with a strong gallop out for another furlong (roughly 40 seconds total for a breeze).

Conclusion

The findings of exercise research are often varied and contradictory due to many research variables making comparisons and conclusions difficult. In addition, most of the research of musculoskeletal issues in racehorses uses racing data, but most injuries occur during training

Because more research is needed, there remain conflicting views of the effects of racing on horses before skeletal maturity and the most effective and safe way to introduce speed exercise. At present, the data suggests that distance and speed be implemented gradually and should include high-speed work at full racing speed.

The racing industry must continue to work cooperatively to address the welfare concerns associated with horses experiencing DMD.

Is all-weather racing no longer the poor relation?

By Amy Lynam

For much of 2018, racing fans waited with bated breath for the return of Enable. Musings on when and where the wonder mare would reappear were many and varied, but few predicted that the Arc De Triomphe heroine would make her seasonal debut at Kempton on the polytrack surface.

Almost two years prior, the regal Juddmonte homebred, who had garnered high regard at home, made her very first racecourse appearance on Newcastle’s Tapeta track. That fateful day was the 28th of November 2016, when, of course, flat racing had left the turf for the winter months, narrowing John Gosden’s choice to two: run his future star on the all-weather, or not until March.

Enable winning the Arc de Triomphe

Gosden did, however, have turf options in September of 2018, and when quizzed on the decision to run a then five-time Gp1 winner on the all-weather, he had no hesitation: “We had aimed Enable at York, but it came about a week or ten days too early, so Kempton came at exactly the right time. The fact that it was on the all-weather didn’t concern me, as I knew exactly what I was going to get.”

For Enable’s return in the Gp3 September Stakes, the going was described as standard to slow, whereas on the very same day, Ascot raced on good to firm (good in places), while the going at Haydock was heavy. There are few surprises in the going on the all-weather; after all, the clue is in the name, and its consistency is very much appreciated by John Gosden, who says, “When the ground goes too firm in the summer, or during drought, or it becomes bottomless at the end of autumn, the all-weather is a nice place to be. It’s consistent, with bounce, and you can ride a proper race on it.”

It would, however, be unfair to look at all-weather racing as one entity, with “all-weather” encompassing various surfaces, mainly fibresand, polytrack and Tapeta™. Not only this, but each racecourse has its own shape and quirks, as well as its own race programme. Just as on the turf, no two courses are the same.

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Gosden is just one trainer who, unsurprisingly, has some favourites, as he shares, “The all-weather track I like the most is Newcastle; it’s very fair and has a good Tapeta surface. It has always been a fair, sweeping course; there are not too many hard luck stories there.” His favour for other all weather tracks is not quite so strong, as he continues, “There’s no doubt that at the likes of Lingfield, you get some unevenly-run races, where they slow the pace down early on and sprint in the straight.”

The opinions of trainers on particular tracks undoubtedly has a great influence on what horses, including what standard of horse, they will run at each. Though he has less hands-on experience with the all-weather racecourses in the UK, French-based trainer John Hammond is impressed by the surface at Lingfield, saying, “I have walked the all-weather track at Lingfield, and it is ‘night and day’ when compared to the all-weather tracks in France.”

When discussing all-weather racing, Hammond is keen to stress the importance of how each track is managed. “All-weather tracks need to be very well maintained and managed by very good groundsmen. I don’t think they pay enough attention to these tracks in France, and they often get too quick.” Hammond could not recommend French all-weather courses’ consistency as Gosden had, as he says, “The all-weather tracks here vary considerably. I wouldn’t mind running a good horse at Lingfield, or Kempton, but Chantilly can be a bit quick.”

All-weather surfaces have been touted for their lack of fatal injuries, but John Hammond sees a different type of injury on all-weather tracks, and this is one of the reasons he does not have many runners on the surface. “I do think young horses suffer from racing on the all-weather,” he says. “I see an increase in bone bruising to the hind cannon bone due to the fact that there is no slippage on synthetic surfaces.” Hammond gained experience in California before taking out his training licence, which has had some effect on his views. “America has torn up most of it’s all-weather tracks. They may have been applauded for fewer fatal injuries, but bone bruising causes intermittent lameness. This can leave a horse runnable but not performing at its best.”

When questioned on potentially running his stable stars on the all-weather, Hammond said, “I wouldn’t be keen on running my top horses on the all-weather in France. If the French all-weather tracks were a bit softer, I might be more keen on it. It didn’t do Enable any harm!”

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