July 28, 2022 – Even if you’re not a horse owner, you’ve probably heard that a broken leg is a serious problem for horses and ponies. Although most news coverage of these tragic events focuses on racing horses, any horse is at risk for these life-threatening injuries. A team of Foundation-funded researchers at the University of Illinois at Urbana-Champaign (UIUC) are hoping to improve the odds for horses by seeing if a carefully controlled exercise program in foals can prevent leg fractures later in life.
The majority of leg fractures occur when horses are between 2 and 10 years of age. Since most horses don’t reach complete skeletal maturity until they’re at least 4 years old, the research team, led by Dr. Annette McCoy, Associate Professor of Equine Surgery, and Dr. Mariana Kersh, Associate Professor of Mechanical Science and Engineering, wondered if there might be a way to strengthen a horse’s legs before skeletal maturity, which in turn might prevent fractures when they’re older.
“We know from another study that mild exercise early in life is associated with positive effects in horses, but exactly how it stimulates bone growth in areas susceptible to fractures is still unknown,” said Dr. McCoy. “Exercise interventions earlier in their lives might better prepare a horse’s bones to face the mechanical forces they will see in their late adolescence and adulthood.”
Dr. McCoy’s research draws on information from human medicine, where studies show that children who exercise are less prone to injury as adolescents and adults, and that bone changes are sustained over time. In a recent, separate Foundation-funded study, Dr. McCoy found that pasture-raised foals in their first year of life are relatively inactive about 85% of the time – a surprisingly high percentage. The group wondered whether this low level of voluntary exercise during the period of most rapid growth could contribute to bone injuries when horses are put into work as young adults.
The team also knew that too much exercise could have a detrimental effect on foals. Any exercise program should increase activity without over-stressing the foal.
The team’s project is expected to take two years. During the summer of 2021, the UIUC team enrolled the first six Standardbred foals, located on the University of Illinois Horse Farm, in the study.
Beginning when each foal was 8 weeks old, the group performed baseline computed tomography (CT) exams on each foal’s forelimbs to create a three-dimensional picture. The exams measured bone properties, including density and volume.
Foals were then divided into two equal groups. Three foals participated in an 8-week exercise plan, consisting of 1,500 yards of fast trotting in a field once per day, five days per week. The other three foals served as non-exercised controls.
When each foal reached 16 weeks of age, the team performed another CT scan of their limbs to compare differences in bone development. When the foals are about 1 year old, the team will take one final CT scan to see if any changes remain after the conclusion of the program.
All the data will be combined into a computer model to help predict the effects of a variety of exercise interventions on bone properties without having to test them in live horses.
The team recently enrolled the final group of six foals into the study and some are beginning their training program. Dr. McCoy hopes to have all their data analyzed by the end of summer 2023.
Although horses come in many shapes and sizes, Dr. McCoy hopes her results will help better manage foals of all breeds destined for activities where front leg fractures are common.
“Most foals, regardless of breed, spend the first year of their lives sleeping, standing and walking,” said Dr. McCoy. “Because we’re really focused on the pre-training period, I think that our findings should be applicable across breeds.”
Dr. McCoy’s group has already presented some of their early findings and they’re excited about what they’ve uncovered so far.
“One of our goals with this project was to create a computer model that we could use in the future to virtually test exercise interventions in foals,” said Dr. McCoy. “What one of our graduate students discovered is that the bones of foals react differently than adult horses to mechanical forces. This meant we couldn’t use the existing adult horse modeling systems for our study – we created something completely new. Nobody had demonstrated this before, and our student won the PhD competition at a recent meeting for this discovery!”
We look forward to what Dr. McCoy and team will learn and we’re hopeful that their findings could help prevent devastating front leg fractures for equine athletes and all horses.