Reducing Wind Surgeries in Thoroughbreds: Harnessing Field Data for Genetic Selection

Article by Dr Erwin Koenen and Richard Birnie

Wind Surgery (WS), also known as ‘wind operations’ or ‘wind ops’, is a term used to describe a collection of surgeries performed on the upper respiratory tract (URT) of the horse, typically the larynx (throat). These surgeries aim to alleviate conditions that cause obstruction of airflow and, therefore, limit oxygen supply to exercising muscles, impacting athletic performance. 

Although WS is generally an effective treatment of upper airway conditions, there is growing interest in curbing them for both animal welfare and financial reasons. For many years, trainers and breeders have considered endoscopic data when buying at sales. Selecting horses with better scoping data for racing and breeding is expected to reduce the risk of URT-related diseases and resulting surgeries. Breeders might realise additional reductions if they could also consider information on the variation in WS among progeny groups when making selection decisions. 
In 2018, the British Horse Racing Authority (BHA) introduced the requirement that trainers declare if a horse racing in Britain has had a WS since their previous race. This routinely collected field data may support the promising avenue of reducing WS by genetic selection. 

In this article, we discuss the different types of surgeries, the use of endoscopic examinations and the opportunities and challenges of leveraging WS declarations for genetic selection.

Wind Surgeries

The term ‘wind surgery’ encompasses the following surgical procedures:

• Tie-back, also known as a prosthetic laryngoplasty. This is utilised for the treatment of roarers, also known as recurrent laryngeal neuropathy (RLN). 

• Hobday procedure, also known as a ventriculectomy or ventriculocordectomy. This is also utilised in the treatment of roarers and is frequently performed in conjunction with a tie-back procedure. 

• Tie-forward, for the treatment of dorsal displacement of the soft palate (DDSP)

• Soft palate cautery, for the treatment of DDSP.

• Epiglottic entrapment surgery, for the treatment of epiglottic entrapment (EE).

Wind surgeries can have welfare implications, for example, if a horse suffers post-surgical complications such as infection or difficulty swallowing. Wind surgeries can also have significant financial implications due to the cost of the surgery itself and the potential loss of earnings due to time off for the procedure. Many WS procedures have widely reported high success rates; for example, it is realistic to expect horses undergoing a tie-back procedure to have success rates of 70-80%, a figure considered to be irrespective of the degree of RLN present. However, no surgical procedure is 100% effective in treating their respective upper airway condition. This means that a certain percentage of horses requiring WS will not return to the same pre-athletic ability they had prior to disease development, again having financial implications on a horse’s potential winnings.

Information on the proportion of racehorses that have had a WS is scarce. To get a preliminary estimate, we studied the WS declarations of 1,000 randomly selected racehorses that ran in Britain between January and May 2024. In this sample approximately 15% of the horses have had at least one WS in their career. As expected, higher frequencies were found for horses in National Hunt races than in Flat races.

Endoscopic Examinations
Early detection of conditions requiring WS is difficult as they do not typically manifest in youngstock but instead frequently present during a horse’s athletic career. Thoroughbred racehorses typically present for surgical management of RLN at 2-3 years of age. Despite this, at most major thoroughbred yearling sales, individual animals undergo post-sale URT endoscopic examinations to assess for disease processes affecting the upper airways, including RLN, DDSP and EE amongst several other conditions. The presence of any one of these disease processes allows for the prospective purchaser to cancel the sale.

Several studies have found a relationship between endoscopic observations in yearlings, particularly the incidence and severity of laryngeal pathologies such as RLN, and later racing performance. The most recent study examined 1,244 Australian thoroughbred yearlings’ URT endoscopic examinations and suggests that resting laryngeal function, associated with the degree of RLN, can be a useful predictor of future racing performance and earning potential. For example, the mean earnings of yearlings graded with a ‘normal’ larynx (condensed Lane scale) was AU$20,100 (£10,453 / €12,271) whereas it was only AU$1,000 (£520 / €610) for those graded with an ‘abnormal’ larynx. 

Although the URT endoscopic data set collected from yearling sales has many valuable applications, these are typically more pertinent to purchasing recommendations and is unlikely to be used for large-scale genetic evaluations. 

Genetic evaluation of WS 

The feasibility of genetic evaluation based on routinely reported WS data largely depends on the presence of natural genetic variation, which may differ per individual surgeries. Heritability estimates, indicating the relative contribution of genetics, for the individual surgeries are not yet known. However, moderate to high heritabilities have been reported for RLN, one of the conditions often requiring WS. Several studies have reported a positive genetic correlation between height and RLN, with taller horses having an increased risk of RLN development. It has been hypothesised that selecting against these genes could result in a shorter population of horses which may impact on athletic performance. Although the exact mode of inheritance remains largely unknown, it is speculated to be polygenic, with numerous genes contributing incrementally to the overall genetic variation and development of RLN. We generally also assume that genes from both parents on average contribute equally to the risk of RLN. Research into the genetic components of DDSP and EE is very scarce.

Once the genetic variation of WS data has been confirmed, breeding organisations can develop statistics indicating the genetic quality of individual horses. A first possible step in this direction might be publishing the average WS incidence for commonly used sires. A more advanced step might be a genetic evaluation based on WS data and pedigree. Such statistical procedures, already routinely implemented in many livestock breeding programmes, optimally combine family information and adjust for non-genetic effects such as age and sex. Breeders can use the resulting estimated breeding values to better identify stallions and mares with a lower genetic risk for requiring WS. The reliability of an individual breeding value depends on the amount of data used, which is low for horses with no offspring and limited pedigree information but high for sires with many offspring. 

Another potential data source for breeders is DNA testing based on the relationship between mutations in the DNA and the inherited predisposition for WS. Although genome-wide association studies (GWAS) have identified variants that relate to RLN, their predictive value has been too low to develop and commercialise highly reliable DNA tests. However, the use of estimated breeding values based on field data may boost the power of ongoing GWAS studies to identify predictive variants.

Impact of genetic selection

Genetic selection operates as a long-term strategy, with noticeable improvements materialising in subsequent generations, albeit typically in modest increments. Nonetheless, experiences with breeding programmes in other livestock species, such as cattle, pigs and poultry, underscore the transformative potential of systematic selection in reshaping population dynamics over time. Unlike non-genetic interventions such as nutrition or training, the outcomes of genetic selection are permanent and cumulative. Moreover, genetic selection often proves cost-effective, especially when leveraging existing data collection practices. 

However, for the widespread adoption of genetic selection against WS within the industry, stakeholders' acceptance is crucial. While publishing breeding values fosters transparency and aids genetic progress, it may encounter resistance from some owners unaccustomed to such openness. Furthermore, given that many Thoroughbred breeders lack familiarity with rational selection based on breeding values, there is a risk of misguided expectations and insufficient support within the sector. Hence, collaborative efforts with stakeholders are imperative both in the development and utilisation of genetic metrics for health and welfare traits to ensure their integration into breeding practices.

Conclusion

The wealth of recorded WS field data in Britain, which was initially intended for the betting public, offers an exciting prospect for exploring its potential application in genetic evaluations. This dataset provides an unprecedented opportunity to reliably study the genetic variation of commonly occurring URT conditions requiring WS. Continued research into the components of the underlying operations, coupled with robust stakeholder engagement, holds promise for yielding valuable insights. Ultimately, such endeavours could empower breeders to implement strategies aimed at effectively mitigating the prevalence of WS within the Thoroughbred population.

References

• Ahern, B.J., A. Sole, K. De Klerk, L.R. Hogg, S.A. Vallance, F.R. Bertin and S.H. Franklin, 2022. Evaluation of postsale endoscopy as a predictor of future racing performance in an Australian thoroughbred yearling population. Aust. Vet. J. 100: 254-260.

• Boyko, A.R., S.A. Brooks, A. Behan-Braman, M. Castelhano, E. Corey, K.C. Oliveira, J.E. Swinburne, R.J. Todhunter, Z. Zhang, D.M. Ainsworth and N.E. Robinson, 2014. Genomic analysis establishes correlation between growth and laryngeal neuropathy in Thoroughbreds. BMC Genomics 15: 1-9.

• Dixon, P.M., B.C. McGorum, D.I. Railton, C. Hawe, W.H. Tremaine, K. Pickles and J. McCann, 2001. Laryngeal paralysis: a study of 375 cases in a mixed‐breed population of horses. Equine Vet. J. 33: 452-458.

• Ducharme, N.G. and F. Rossignol, 2019. Chapter 46: Larynx. In: J.A. Auer, J.A. Stick, J.M. Kümmerle and T. Prange. Equine Surgery (Fifth Edition) (pp. 734-769). Elsevier.

• Dupuis, M.-C., Z. Zhang, T. Druet, J.M. Denoix, C. Charlier, P. Lekeux and M. Georges, 2011. Results of a haplotype-based GWAS for recurrent laryngeal neuropathy in the horse. Mamm. Gen. 22: 613-620.

• Garrett, K.S., S.W. Pierce, R.M. Embertson and A.J. Stromberg, 2010. Endoscopic evaluation of arytenoid function and epiglottic structure in Thoroughbred yearlings and association with racing performance at two to four years of age: 2,954 cases (1998–2001). J. Am. Vet. Med. Assoc. 236: 669-673.

• Hawkins, J.F., 2014. Advances in equine upper respiratory surgery. John Wiley & Sons.

• Herdan, C., B. McGivney, K. Gough, E. Hill and L. Katz, 2014. A Single Nucleotide Polymorphism (BIEC2-808543) on Eca3 is associated with Recurrent Laryngeal Neuropathy independent of height in Thoroughbred horses. Equine Vet J. 46: 34.

• Ibi, T., T. Miyake, S. Hobo, H. Oki, N. Ishida and Y. Sasaki, 2003. Estimation of heritability of laryngeal hemiplegia in the Thoroughbred horse by Gibbs sampling. J. Equine Sci. 14: 81-86.

• Miller, S.M., 2020. Endoscopic recurrent laryngeal neuropathy grade prevalence in a sample of thoroughbred yearlings at public auction in South Africa (2013–2019). J. S. Afr. Vet. Assoc. 91: 1-5.

How trainers promote best welfare practice across Europe

"Mens sana in corpore sano" - is a well known Italian phrase which translates to “a healthy mind in a healthy body" is a fundamental principle for every athlete, and racehorses are true athletes of the sporting arena. Just like their human counterparts, the performance of a racehorse depends not only on their physical condition but also on their mental well-being. The issue of animal welfare in horse racing is not just a matter of ethics or sensitivity, but the foundation upon which the integrity of the entire sport rests.

The concept of equine welfare extends beyond the mere absence of disease or injury. It concerns the quality of life of the horses, including their daily treatment, living conditions, access to open spaces, appropriate nutrition, and the ability to express natural behaviours. Moreover, it includes ethical training practices that respect the animal's physical limits, avoiding bad training and stress.

In the context of racing, equine welfare is scrutinised not only by industry insiders but also by the public and animal rights activists. Our focus in this section of the article is on the evolution of welfare practices in the leading countries of European horse racing: Great Britain, France, Ireland and Germany. 

The goal is to understand not only the current state in terms of equine welfare but also to identify trends and areas for improvement, reflecting on the importance of an ethical and responsible approach to these extraordinary athletes.

GREAT BRITAIN - HORSE WELFARE BOARD (BHA)

The Horse Welfare Board, inclusive of representatives from the BHA, racecourses, and horsemen, unveiled a five-year welfare plan in 2020 to elevate horse welfare in British racing. This plan is dedicated to ensuring a "life well-lived" for racehorses, with a focus on traceability, safety, well-being, alongside initiating the industry's most extensive data project. It targets enhancing health care practices, ensuring lifelong responsibility, reducing injuries, and fostering public trust through transparency and ethical practices. Additionally, the strategy commits to developing a Code of Ethics and advancing veterinary care and injury prevention. Importantly, the implementation team is collaborating with the industry on 26 strategic projects, backed by funding from the Horserace Betting Levy Board (HBLB) since 2019 and a recent £3 million grant from the Racing Foundation, to realise these goals.

In the array of projects undertaken by the Welfare Board to bolster safety and uphold equine welfare standards, there are a few that stand out as being exceptionally cutting-edge, such as the: Thoroughbred Census, Equine Vision Project, Data Partnership.

Thoroughbred Census

The project aims to enhance the traceability of retired thoroughbreds, enabling better support for owners and the adaptation of welfare initiatives by British Racing and Retraining of Racehorses (RoR). It involves a six-month census, in partnership with RoR, collecting detailed information on retired racehorses to improve aftercare and respond quickly to equine disease outbreaks.

Equine Vision Project:

“We try to look through the horses’ eyes” - Mike Etherington-Simth

In 2017, the BHA and Racing Foundation funded research into equine vision to enhance hurdle and fence safety. Horses, seeing fewer colours than humans, struggle to distinguish between hues like red, orange, and green. The study assessed the visibility of orange markers on racecourse obstacles against alternative colours, considering how weather conditions affect perception.

Data Partnership

This project seeks to enhance racehorse safety and welfare by analysing risks and factors leading to injuries and fatalities on racecourses and during training in Great Britain. It utilises extensive data on races and training practices, employing advanced statistical models to identify risk factors. The initiative, in collaboration with industry stakeholders, aims to provide evidence that informs decisions and measures to minimise risks, directly contributing to the betterment of racehorse welfare.

FRANCE - FRANCE GALOP

France Galop is deeply committed to promoting high standards of horse welfare, aligning with the 8 principles outlined in the "Charte Pour le Bien-Être Équin". This commitment is evidenced through various initiatives, including the inspection of facilities by France Galop veterinarians for new trainers who have acquired their flat racing licences. These checks, part of the certification process, aim to ensure that the infrastructure is suitable for housing horses. In 2021, a total of 410 training centres were inspected by the veterinarians of the Fédération Nationale des Courses Hippiques. The vets also check for prescribed medications and substances on site, adhering to a “zero tolerance” policy.

IRELAND - THOROUGHBRED WELFARE COUNCIL (HRI)

“They have horse welfare right at the forefront of everything they do and I would say they are doing a very good job”  Joseph O’Brien

In 2021, the Irish Thoroughbred Welfare Council was assembled to act as an advisor to the Board of HRI and assist in devising policies on welfare matters. HRI gathered 60 industry participants in a co-design project to create a manual called “Our Industry, Our Standards,” aiming to establish a system where welfare standards are verified and measured. These standards include good feeding, good housing, good health and good well-being. Additionally, the Thoroughbred Council is collaborating with IHRB, Weatherby’s, and the Department of Agriculture to create a traceability system that will ensure every horse always has a known link to the responsible person. 

Best-Turned-Out League

To promote and encourage the implementation of good animal care and welfare practices, HRI has introduced the “Best-Turned-Out League,” which aggregates these prizes from across the country into a league table with substantial prizes from six different categories, highlighting the impressive standards maintained across the industry. The primary caregivers, who are often lifelong careerists, are our industry employees. 

GERMANY - DEUTSCHER GALOPP

Deutscher Galopp, has notably advanced equine welfare within racing in recent years. Not only has it raised the quality standards of horse care within stables, monitored through surprise veterinary checks, but it has also started to develop an intriguing project that monitors the physical development of racehorses.

Physical Maturity Check for 2-Year-Olds Before Training

Deutscher Galopp has implemented regulations requiring that every horse must pass specific veterinary checks. These checks are designed to ascertain sufficient physical maturity before a horse enters into training. A second assessment is conducted shortly before the horse can start in a race, to confirm its physical fitness for competition.

For this section of the article, we canvassed opinion from a selection of industry professionals for their perspectives on issues related to equine welfare. 

Q: What role does horse welfare play in your training practices and what specific measures do you implement to safeguard the physical and mental well-being of the horses?

"The welfare of my horses is central to me; it is the most crucial element for the success of my business” asserts Seamus Mullins, a sentiment unanimously echoed by all interviewees who have long regarded animal welfare as a key factor from the outset of their careers in the racing sector. When delving into the practicalities of ensuring each horse's welfare is honoured, Joseph O'Brien highlights the significance of tailoring care to individual needs. "It's crucial not to generalise, as what satisfies one horse might not suit another," he explains. This underlines the necessity of adapting training and rest schedules to cater to their unique preferences and inclinations, guaranteeing their well-being and happiness.

Luca Cumani, who since retiring from training has remained active within the industry, including a term as a director of the BHA and as a pre-eminent breeder emphasises the importance of observation to understand each horse's psychological capabilities and preferences.

Seamus Mullins discusses the regular turnout of horses in individual paddocks while ensuring they are always in association with other horses. The stables are varied to suit different preferences, emphasising the need for regular updates to training methods and facilities to keep the horses in the best condition possible.

Peter Schiergen, Nastasja Volz-Degel, and Alessandro Botti all share this commitment to horse welfare, implementing daily routines, wellness programs, and training methods tailored to the individual needs and physical aptitudes of each horse. They focus on creating a comfortable environment for the horses, using modern facilities such as solariums, water treadmills, and magnetic blankets for massage, highlighting a collective effort to maintain high welfare standards in the racing industry.

Q: How do you educate your staff or team members about the importance of animal welfare?

"I always said to the riders: the relationship with the horse you ride should be viewed as a partnership, akin to that with your wife or daughter, and should be treated with the same respect and care" Cumani explains with a touch of warmth. The stable staff plays a pivotal role in the implementation of animal welfare, which is why, as the interviewees emphasise, it's crucial to focus on their education and enhance their knowledge to the fullest. "We want our staff to become better horsemen," states Schiergen. 

Beyond the training provided internally within their stables, some trainers, like Alessandro Botti, with the support of AFASEC (the Association de Formation et d'Action Sociale des Ecuries de Courses - which roughly translates to Association for Training and Social Action of Racing Stables), have decided to offer courses in equine ethology led by experts brought in from outside. This initiative not only sparked significant interest among their staff but also led to an improved approach to working with horses.

Q: The risk of injuries is an inherent component in all sports, including horse racing. What is your opinion on this statement, and what specific actions do you take to minimise the risks?

"Risks are everywhere, especially in competitive activities, whether involving humans or animals, there's a significant element of risk," are the words of Cumani, which also resonated with others we interviewed. 

The consensus is that, unfortunately, injuries are inevitable despite efforts to minimise them through practices and care that respect the physical state of the horse. "We try to minimise the risks by checking every horse before a race and during training, we never push the limit of a horse if he isn't ready enough” underlines Schiergen, “we have to get the message across that we are doing all our best to minimise the risks at all accounts”, adds Mullins.

Q: What role do you believe transparency plays in communicating to the public the importance placed on the welfare of racing horses in daily activities, and how do you ensure that this information is effectively shared with the general public?

“There are fewer and fewer people growing up with animals and in farming, and as a result, this is why we need to show through platforms what we do because things we take for granted, someone who has never been to a racing yard may not realise what happens,” says O'Brien. He adds, “It is important to give people access to behind the scenes, and this is why we try to be quite active on social media and encourage people to come to our yard, so that they realise the amount of passion that staff puts in their daily work.”

Public involvement, to make them part of the daily practices of stable life, is crucial, as our interviewees from various parts of Europe maintain. Thanks to numerous activities promoted by the racing authorities of the interviewees' respective countries, Open Day events allow the public to participate in stable life. 

Many trainers, like Seamus Mullins, have noticed a significant increase in participation in recent years, “Ten years ago, participation in the UK was about 100, while in 2023 it was more than 500. Moreover, people who participate often express surprise at how well race horses are treated.” However, all the trainers, like Alessandro Botti affirms, it is necessary to increase content on social media, to give the possibility to everyone, every day and in every part of the world, to participate in the daily life of horses in various stables.

Q: What do you think will be the future trends in horse welfare in Racing in the coming years?

All the trainers interviewed are convinced that the standards of equine welfare in racing are already very high. However, they unanimously believe that social pressure from activists will continue to grow, making it necessary to increase transparency and public engagement. Joseph O'Brien emphasised the importance of education: "What I think really has to be put to the forefront is educating people who are not involved in racing; this will be the biggest challenge." 

Given the insights on how Racing Authorities operate in terms of Horse Welfare and the daily interest and commitment of trainers, the trend seems to be very positive and reflects very high standards. It is essential, however, that countries collaborate with each other to inspire one another, further improving equine welfare practices, as Helena Flynn, the British Horse Welfare Board Programme Director emphasises "We love these animals and do our best to ensure they are protected, and thus it would be beneficial if the results of various state projects could contribute to inspiring everyone internationally." Therefore, the issue of equine welfare in racing is a complex mosaic of care, respect, and dedication towards the thoroughbred racehorse. Recognising and acting for their welfare is not just a moral duty but the foundation on which to build a fair, sustainable, and most importantly, animal-respectful racing industry.