Can Body Shape Predict Metabolic Issues in Horses?

Imagine this superpower: scanning a herd of horses and reliably choosing which ones will be beset with metabolic challenges. Out of the realm of possibility? No, according to scientists, who are learning more and more about your horse’s body shape and what it means for his well-being.

Researchers at the Queensland University of Technology set out to determine the relationship between morphometric measurements of body condition and certain hormone concentrations in ponies*.

Twenty-six ponies were used in the study and underwent an array of measurements: body condition score (BCS), neck circumference, cresty neck score (CNS), girth circumference, and height. An oral glucose test was then performed and blood samples collected just prior to and two hours after dosing, and these samples were analyzed for serum insulin, serum triglyceride, and plasma adiponectin concentrations. Adiponectin is a protein hormone integral to carbohydrate and lipid metabolism.

The ponies were separated into three groups based on body weight: ideal body weight (BCS ≤7 and CNS ≤2; 11 ponies); regional fat deposition (BCS ≤7 and CNS ≤3; 9 ponies), or obese (BCS ≥8; 6 ponies). Results from the oral glucose test revealed that some of the ponies were healthy, while others had equine metabolic syndrome (EMS).

Postprandial serum insulin was positively correlated with CNS, but BCS and girth and neck circumference did not correlate with the hormonal variables. “Ponies with regional adiposity, or fat pads, had greater insulin response to the oral glucose test than those ponies in ideal body weight, but obese ponies did not differ from those of ideal weight or regional adiposity,” the researchers explained.

What did the researchers learn? While BCS is often used to predict endocrine dysfunction, such as EMS, a better indication might be CNS.

“Diligent management can help keep easy keepers from becoming victims of EMS,” said Catherine Whitehouse, M.S., a nutrition advisor at Kentucky Equine Research. “At the top of the to-do list is the implementation of a diet that meets the nutritional requirements of the horses and ponies without offering too many calories. Moderation is key.”

To this end, a diet composed of forage fed at about 1.5-2% of body weight and a vitamin and mineral supplement, such as Micro-Max (Gold Pellet, Nutrequin, or Perform in Australia), will meet the nutritional requirements of most metabolic horses, especially those that are asked to do little exercise. “Hay selection is important, as many metabolic horses do not need premium forage. Most do nicely on clean, weed-free grass hay of average quality,” Whitehouse said. Grazing must often be limited with restricted access to pasture, a grazing muzzle, or allocation to a drylot or a field with minimal grass.

Another important, though often disregarded, management strategy is daily exercise, Whitehouse said. Researchers believe that as little as 30 minutes of forced exercise per day can help keep signs of EMS from developing.

The nutrition consultants at Kentucky Equine Research are available to help plan a feeding program that is best for your horse.

Would you rather study more? In-depth feeding guidelines are available in the booklet Nutritional Management of Metabolic Diseases, assembled by the health-care team at Kentucky Equine Research.

*Fitzgerald, D.M., M.N. Sillence, and M.A. De Laat. 2018. Morphometric measurements for identifying equine metabolic syndrome. In: Proc. Australasian Equine Science Symposium 7:29.