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Healthy Foal, Healthy LifeBy Kentucky Equine Research Staff · February 7, 2017

Horse owners know that certain horses and ponies, those so-called “easy keepers,” have an increased risk of developing insulin-glucose abnormalities that contribute to equine metabolic syndrome (EMS). Other factors influencing metabolic abnormalities, especially events occurring early in a horse’s life, remain unclear.

“Some studies show that conditions experienced by a developing fetus affect aspects of its overall health as an adult,” explained Kathleen Crandell, Ph.D., a Kentucky Equine Research (KER) nutritionist.

“For example, foal with low birth weight caused by mare undernutrition or placental insufficiency, which results in decreased blood flow to the growing foal, can result in abnormal glucose metabolism and insulin action later in life,” Crandell added.

In other words, foals are not completely cocooned safely in their dam’s womb throughout gestation, isolated from all potentially harmful influences. Further, the environmental conditions a foal experiences early in life—particularly during the delicate period immediately following birth—may impact health later.

These concepts were recently reinforced by a group of researchers from the University of Cambridge in the United Kingdom. In their study*, Valenzuela and coworkers administered the hormone ACTH (adrenocorticotrophic hormone) to nine male and female pony foals for the first five days of their lives. ACTH stimulated the production of the stress hormone cortisol, thus mimicking hormone levels experienced by stressed foals in the neonatal period.

When those foals turned one and two years of age, glucose-insulin dynamics and body weight were measured. While overexposure to stress hormones like cortisol in the neonatal period did not significantly influence glucose-insulin dynamics in those foals as yearlings or two-year-olds, the researchers noted dysregulation typically occurs after the horse matures completely, and later testing may yet show differences. The study also found that fillies were more prone to insulin sensitivity than colts as yearlings, and that body weight and insulin action were related in both sexes.

“Sex of the animal and environmental factors during fetal and early neonatal life are likely to be important in determining postnatal metabolic and endocrine phenotype,” the researchers concluded.

“Understanding factors that contribute to altered glucose and insulin dynamics will helps owners prevent the development of equine metabolic syndrome, which is associated with the risk of laminitis,” concluded Crandell, “Still, more research is needed.”

In the meantime, other research studies support dietary supplementation with fish oil for horses with alterations in glucose-insulin dynamics. Products like EO•3™ influence insulin dynamics with dietary-induced insulin resistance.

Valenzuela, O.A., J.K. Jellyman, V.L. Allen, et al. Effects of birth weight, sex and neonatal glucocorticoid overexposure on glucose-insulin dynamics in young adult horses. Journal of Developmental Origin of Health and Disease. In press.