By: Dr Rosie Alcorn BVSc PG Cert VPS Cert AVP MRCVS
Skeletal injuries remain a major concern within the racing industry, as well as for the wider public watching the sport. The media often highlights catastrophic injuries in headlines, reinforcing the importance of ongoing research and preventative management.
As we approach mid-season, it is timely to review how we can support our horses’ bone health and examine the latest evidence surrounding racehorse bone development.
Bone is composed of three types of specialised cells and an extracellular matrix.
These cells include:
Osteoblasts – responsible for forming and hardening bone by laying down extracellular matrix
Osteoclasts – break down old or damaged bone so osteoblasts can replace it with stronger bone
Osteocytes – maintain bone strength during modelling and remodelling
The extracellular matrix is primarily made up of the protein collagen.
Approximately 70% of a bone’s strength comes from its mineral content, with calcium accounting for around 35% of the bone’s structure. Despite appearing rigid and static, bone is a dynamic tissue that constantly adapts and changes throughout training.
Bone remodelling occurs when bone is placed under mechanical stress. This stress creates microdamage, which stimulates bone cells to repair and strengthen the affected area. As a result, bone density increases - a process known as remodelling.
However, during the remodelling phase, bone is temporarily weakened and more susceptible to further injury. This highlights the importance of carefully balancing training intensity with adequate rest and recovery.
Research shows that low-intensity exercise produces only minor changes in cannon bone density. In contrast, short periods of high-speed training significantly increase bone density when compared with long, slow canters. Strategic high-speed work therefore plays a critical role in stimulating optimal skeletal adaptation.
Young horses entering training for the first time are often at the greatest risk of conditions such as shin splints.
Many young horses transition from pasture-based systems, where they may move and play freely for several hours a day, into training environments that involve prolonged stabling. This sudden reduction in voluntary movement can influence bone adaptation.
Turnout has been shown to improve bone density when compared with extended stabling. Conversely, studies indicate that prolonged confinement may reduce bone density, making management practices an important consideration for skeletal health.
Recent research also suggests that horses entering training at two years of age may have certain advantages over older counterparts, as earlier exposure to training stimuli may promote greater bone density development.
Diet plays a fundamental role in supporting bone strength and density.
As discussed earlier, the extracellular matrix of bone is primarily composed of collagen, a structural protein. Proteins are made up of amino acids, some of which must be supplied through the diet.
Providing the correct quantity of high-quality protein is therefore essential in racehorses to support bone development and repair.
Calcium and phosphorus make up a substantial proportion of bone mineral content. Both the total amount supplied and the dietary calcium-to-phosphorus (Ca:P) ratio are critically important.
An imbalance in this ratio may result in calcium being mobilised from the skeleton, potentially leading to bone demineralisation and increased injury risk.
Several vitamins are essential for skeletal health:
Vitamin A supports the development of osteoblasts
Vitamin D is necessary for efficient calcium absorption
Vitamin K plays a key role in the production of osteocalcin, a hormone involved in bone metabolism and mineralisation
Research has demonstrated that supplementing vitamin K increases osteocalcin production. Published studies in two-year-old Thoroughbreds suggest that vitamin K supplementation may improve bone mineral density and potentially reduce the risk of bone injury during training.
For a scientifically proven Vitamin K supplement, check out Oste:Form by Keyflow Scientific.
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