Building Better Bones: Exercise and Bone Development in Foals

Could mile-long trots protect young foals from lower-leg fractures later in life? Morris Animal Foundation-funded researchers at the University of Illinois at Urbana-Champaign (UIUC) are evaluating the long-term effects of a moderately strenuous exercise plan on bone development in foals.

Lower-leg fractures are a major welfare concern in horses that race or jump competitively, but they can happen in any horse. Understanding the impact of early exercise on growing horses – most horses don’t reach complete skeletal maturity until they’re at least 4 years old – could help prevent fractures. Most fractures happen when horses are between 2 and 10 years of age.

“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. Annette McCoy, Assistant Professor of Equine Surgery at the UIUC College of Veterinary Medicine. “Exercise interventions earlier in their lives might better prepare their bones to face the mechanical forces they will see in their late adolescence and adulthood.”

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McCoy’s study draws 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, McCoy found that pasture-raised foals in their first year of life are relatively inactive about 85% of the time.

Over the next two summers, the UIUC team plans to test 12 Standardbred foals, located on the University of Illinois Horse Farm, beginning when each foal is 8 weeks old. Researchers will first perform a baseline computed tomography (CT) exam on each foal’s forelimbs to create a three-dimensional picture. The exams will measure bone properties, including density and volume.

Foals will then be divided into two equal groups. Half will undergo an 8-week exercise plan, consisting of 1,500 yards of fast trotting in a field once a day, five days per week. The other six foals will serve as non-exercised controls.

When each foal reaches 16 weeks of age, the team will perform 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. McCoy believes the model could be modified for use in horses of all shapes and sizes, because most horses are managed similarly in their first years of life.

“This study will expand our knowledge of effects of early-life exercise on bones that are susceptible to fracture when horses enter into training and competition,” said Dr. Janet Patterson-Kane, Morris Animal Foundation Chief Scientific Officer. “Whatever exercise horses engage in, resilient bone structure is critical to happy, healthy lives for them and their owners.”

About Morris Animal Foundation

Morris Animal Foundation’s mission is to bridge science and resources to advance the health of animals. Headquartered in Denver, and founded in 1948, it is one of the largest nonprofit animal health research organizations in the world, funding more than $136 million in critical studies across a broad range of species. Learn more at morrisanimalfoundation.org.