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From Cause to Cure: Osteochondrosis in HorsesBy Kentucky Equine Research Staff · June 7, 2016

According to experts, both genetic and environmental factors contribute to the development of osteochondrosis (OC), one of the most prominent developmental orthopedic disorders in horses. In this sense, the term “environmental factors” includes nutritional considerations not only for the foal, but also the dam during the latter part of pregnancy.

OC is a failure of bone to form healthy articular cartilage that lines the ends of long bones in joints early in a horse’s life. The result is a defect in the bone and loose flaps of cartilage inside the joint. These cause joint swelling and lameness.

“The exact steps involved in this developmental lapse remain unclear, despite the fact that the condition has been affecting horses and their performance and welfare for a long time,” shared Kathleen Crandell, Ph.D., an equine nutritionist for Kentucky Equine Research.

In a recent review article* on the impact of nutrition on OC, an accelerated growth rate during certain periods of time, probably during peak times when bone turns into cartilage, called endochondral ossification, is associated with OC. The authors also pointed out that horses with OC have higher glucose and insulin responses to feeding diets high in grain. In turn, insulin impacts a variety of processes involved in endochondral ossification.

The study authors also noted, “It is clear that nutrition-related hormonal imbalances may play a role in the development of equine OC, but they are, like unfavorable exercise conditions, a risk factor and not a sole etiological factor.”

Low copper intake by mares is also thought to contribute to OC, in addition to micronutrient imbalances such as excessive cadmium or zinc intake, which both block the absorption of dietary copper. Unfortunately, a clear association between copper intake and OC remains elusive.

Although foals are born with stores of copper in their livers, these levels decline after birth and foals have limited copper intake until they are consuming sufficient quantities of forage. Because copper is believed to support cartilage health, ensuring foals accumulate enough copper in the last part of gestation is important.

Crandell added, “Don’t forget that the calcium and phosphorus balance is important, too. Although high calcium levels do not appear to influence OC in foals, according to the authors, studies show that four times the NRC recommendation of phosphorus resulted in a significantly increased number of lesions.”

For help feeding mares in late gestation and ensuring foals and young horses are fed appropriately, learn more:

Do you want a one-on-one consultation? Check in with an equine nutritionist today.

*Van Weeren, P.R., and K. Olstad. 2016. Pathogenesis of osteochondrosis dissecans: How does this translate to management of the clinical case? Equine Veterinary Education. 28(3):155-166.