A new technique that uses ultrasound findings to predict a racehorse’s likelihood of returning to racing after a tendon injury has been described by researchers.
The study team say the new system will significantly improve racehorse welfare in both the short and long term. It will enable vets and racehorse trainers to make early and informed decisions on a horse’s future – whether to prescribe rest and recovery before racing again, rehabilitation for another career, or immediate retirement.
The ultrasound technique was developed by researchers at the University of Nottingham and Oakham Equine Hospital, both in England, and the Hong Kong Jockey Club.
The researchers created a scoring system for grading tendon injuries in racehorses when they first occur and used this in a large study to determine which ultrasound features will predict whether the horse will successfully race again after rehabilitation.
They have been working with a veterinary ultrasound company, BCF Technology, to develop an app that vets can use to record their ultrasound findings using the new scoring system.
The study team, whose findings are reported in the Equine Veterinary Journal, focused on injuries to the superficial digital flexor tendon. Damage to this tendon is an important health and welfare concern in racehorses. It is generally diagnosed with ultrasound examination.
Standard treatment for tendon injury in a racehorse is the three ‘Equine Rs’ – Rest (until able to race again), Rehabilitation (toward an alternative career) or Retirement.
The authors set out to determine whether the features of such tendon injuries seen in ultrasound images of the front legs of Thoroughbred racehorses could predict a successful return to racing, completing five or more races.
Ultrasound images of 469 horses with forelimb superficial digital flexor tendon injuries were used in the research. The images, taken at the Hong Kong Jockey Club between 2003 and 2014, were evaluated using a previously validated ultrasonographic scoring system. The club has had a standardised recording of clinical records for all racehorses over many years.
Six ultrasonographic parameters were evaluated, including the type and extent of the injury, its location, and the fibre pattern in the injury zone. They also factored in the age, breed and sex of the horses, retirement date, and the number of races before and after injury.
Their predictive model found that clinicians should concentrate on two main characteristics of the tendon injury, each easily assessed by ultrasound at first presentation; the cross-sectional area of the lesion and the extent of disruption to the normally highly ordered pattern of tendon fibres.
The researchers divided cases into the two groups – those with core lesions and those without.
For those with core lesions, the cross-sectional area at the maximal injury zone was the most significant factor determining a successful return to racing. If the lesion was less than 50% of the total cross-sectional area, horses had a 29-35% probability of successfully racing again. If it was 50% or greater, this decreased to 11-16%.
For cases without a core lesion, the longitudinal fibre pattern at the maximal injury zone best predicted a successful return to racing. If the affected longitudinal fibre pattern was less than 75% of the total, horses had 49-99% probability of successfully return to racing, but if it was 75% or more, this decreased to 14%.
“Ultrasound is a quick and easy method of assessing tendon injuries, widely available across veterinary practices,” said lead researcher Dr Rafael Alzola, equine surgery resident at the Nottingham Veterinary School and Oakham Veterinary Hospital.
“The scoring system makes evidence-based decision-making on long-term outcomes feasible and accessible to equine veterinary practitioners.”
Professor Chris Riggs, who is head vet at the Hong Kong Jockey Club, added: “Decisions on future careers for racehorses have to be carefully considered by the horse’s owner, trainer and vet, working together.
“This study is important from a welfare perspective, as it provides the information to help them make decisions which are best for the horse’s long term welfare, as soon as the injury occurs.”
Professor of Veterinary Surgery at the Nottingham Veterinary School, Sarah Freeman, said: “We have worked with leading ultrasound company BCF to develop an app based on the scoring system.
“This will help develop future research studies so similar work can be done for injuries in horses competing in other disciplines.”
It gives veterinary surgeons and technicians the tool to record animal health and diagnostics in one place while they are out in the field.
The full study team comprised Alzola, Riggs, Freeman, Camilla Easter and David Gardner.
Ultrasonographic-based predictive factors influencing successful return to racing after superficial digital flexor tendon injuries in flat racehorses: A retrospective cohort study in 469 Thoroughbred racehorses in Hong Kong.
R. Alzola, C. Easter, C.M. Riggs, D.S. Gardner and S.L. Freeman
Equine Vet J. 2018 Jan 20. doi: 10.1111/evj.12810
The abstract of the study can be read here.