What impact does nutrition and exercise have on bone development in growing foals?

Hoof Nutrition Intelligence is a twice-a-month web segment that is designed to add to the education of footcare professionals when it comes to effectively feeding the hoof. The goal of this web-exclusive feature is to zero in on specific areas of hoof nutrition and avoid broad-based articles that simply look at the overall equine feeding situation.

Below you will find Part 1 of the latest question and answer installment that you can share with your footcare clients.

Q: What impact does nutrition and exercise have on bone development in growing foals?

By Catherine Whitehouse, M.S.

Mechanical loading strengthens bone during growth, so exercise during childhood and adolescence has been shown to have lifelong benefits on skeletal health in humans. Similarly, exercised foals show greater bone size and strength, and resistance to bending and torsional distortion, compared to pasture-exercised control foals.

Because the fetlock joint must withstand incredible forces, high-performance horses, including Thoroughbred and Standardbred racehorses, often sustain injuries at this site. This joint connects the long and short pastern bones, also known as the first and second phalanx.

A recent University of Illinois study of sound Standardbred foals, all trotting-bred, characterized how the long pastern bone adapts to changing loads during growth through the use of regular computed tomography (CT) scans during the first year of life. In addition to measuring strength and composition changes in the bone, researchers calculated strain energy density, which is a biomechanical metric of potential bone remodeling

Growth-related changes in mineral density and bone area at various bone points (distal epiphysis, mid-diaphysis and proximal epiphysis) were assessed. These bone points were further divided into four functional quadrants (dorsal, medial, lateral and palmar).

Mineral density and bone area uniformly increased in the diaphysis and a portion of the proximal epiphysis, the medial quadrant, but not in the fracture-prone lateral quadrant. Strain energy density was constant during growth, indicating bone adaptation to standing quietly. According to prior observation by researchers, this is the primary activity of Standardbred foals, which revealed that 2-5 month old foals spent 80% of their time at a standstill.

The researchers explained that the work provides a baseline longitudinal characterization of normal remodeling of the equine forelimb first phalanx during the first year of life and its effect on strain energy density. This is an essential prerequisite to making evidence-based recommendations for training regimens that may encourage bone growth in areas prone to fracture during development. A properly prepared musculoskeletal system may lead to fewer fractures.

In addition to exercise, proper nutrition of the mare throughout gestation and of the foal during all growth phases fosters future soundness. Nutritional management of young horses starts with an appropriate, good-quality forage. Fortified concentrates can then be fed to meet energy, mineral and vitamin shortfalls.

Aside from hay and concentrates, supplements designed to increase bone health can be used to support young athletes. This should be a supplement that contains calcium and an array of bone-building nutrients designed to increase bone density, with the ultimate goal of promoting long-term soundness.

Catherine Whitehouse is an equine nutrition advisor with Kentucky Equine Research in Versailles, Ky.

Click here to read part 2 of the Dec. 1, 2020 installment of Hoof Nutrition Intelligence: Can most senior horses be left barefoot when they are no longer part of a riding program? Click here to read more installments of Hoof Nutrition Intelligence.