A tablet-mounted three-dimensional scanner shows promises in being able to measure lower leg swelling in horses, according to US researchers.
University of Portland researchers Steven Johnson and Jennifer Symons carried out a pilot study to determine whether a low-cost 3D scanner mounted on a tablet was able to detect differences in limb swelling before and after jumping in horses.
Repetitive loads applied during training and competition are known to contribute to the stress of leg structures in horses.
Swelling in the legs — local fluid accumulation — is a sign of increased stress in these structures. This fatigue contributes to injuries that occur in many different equestrian disciplines.
In the case of sport horses in dressage or showjumping, these injuries can compromise a horse’s competitive career by disrupting training with layups and rehabilitation.
In the case of racehorses, catastrophic musculoskeletal injuries may result in euthanasia.
Currently, horse riders and trainers make training decisions based on visual observations of leg swelling in horses, but these are potentially subjective and imprecise.
Johnson and Symons, from the university’s Shiley School of Engineering, wanted to find out if a 3D scanner would prove useful in objectively assessing physiological responses to elevated, non-routine mechanical stresses.
Five horses training and competing in showjumping activities were used in the study with owner consent. All horses were assessed for general health by study researchers.
For the study, a Structure Scanner made by Occipital in San Francisco, California, was mounted to an Apple iPad and calibrated for use.
The volume of one front lower leg and one rear lower leg was measured in each horse both before and after jumping exercise, with the intensity of the training session decided by each horse’s rider.
Each scan was completed in less than 3 minutes, the researchers reported.
All horses had larger limb volumes after jumping, based on the scan results.
With the exception of one horse, most changes in limb volume were apparent to an experienced observer familiar with lower limb anatomy.
Most horses were found to have increases in lower limb volumes of 4% to 9% following exercise.
However, the youngest horse had changes in limb volume of up to 37%.
“This horse’s rider disclosed that the observed session between scans involved markedly elevated exercise compared to the horse’s routine training. This elevated exercise was not influenced by the researchers and was not executed for experimental purposes.”
Most of the observed changes in limb swelling were considered apparent, but unremarkable to the riders and trainers, the researchers said.
“Therefore, these physiological signs did not warrant alteration in training frequency and intensity.”
However, in the case of the horse whose limb volumes increased by 37%, the rider could see the swelling detected by the scanner and responded with a decreased workload in the following week.
“However, the owner did not perceive any injuries warranting veterinary consult, treatment, lay-up, or rehabilitation. Therefore, the horse continued with routine training in the following weeks and months.”
Discussing their findings, Johnson and Symons said the scanner was able to detect a statistically significant increase in lower leg volumes after jumping, compared to initial scans.
They said the 3D scans and recorded volumes are influenced by operator experience. Three people had used the device, and the two with more initial practice had less variability in recorded volumes compared to a user with no prior experience.
The magnitude of recorded limb volumes may not be considered accurate, they said. Despite this, the observed differences in limb volume may be considered significant.
“The results and conclusions of this pilot study are limited by the small sample size and limited range of jump intensity executed by subjects,” the researchers acknowledged.
“Future studies may seek to evaluate more horses over a wider range of ages and jump heights.
“With continued scientific evaluation, this technology may provide information to guide training and rehabilitation programs to lessen the incidence of injury and maximize potential performance of equine athletes in the future.
“Future studies may also investigate the use of this technology in other disciplines or during rehabilitation from distal limb injuries, particularly superficial soft tissue structures like suspensory branches or the superficial digital flexor tendon.
Measuring Volumetric Changes of Equine Distal Limbs: A Pilot Study Examining Jumping Exercise
Steven Johnson and Jennifer Symons *
Animals 2019, 9(10), 751; https://doi.org/10.3390/ani9100751