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 2 of the latest question and answer installment that you can share with your footcare clients.
Q: What are the chances my somewhat laminitic overweight horse will be insulin resistant?
By Kathleen Crandell, PhD
Horses suffering from obesity and insulin resistance (IR) concerns are at higher than normal risk for laminitis and equine metabolic syndrome. Obesity also strains the joints and leads to exercise intolerance.
While not every obese horse is insulin resistant, and not every horse with IR is obese, some type of relationship is suspected. Likewise, some obese horses fed extremely restricted diets fail to lose weight, so other factors in addition to diet must be considered.
Researchers at the University of Melbourne in Australia are investigating these facets of equine health. Preliminary summaries from these studies are given below.
1. Horses and ponies tend to have different metabolic rates. Ponies are usually somewhat stockier and have heavier bodies for their height than horses. However, some Morgans, Paso Finos and Quarter Horses show a similar body type.
Further study is being conducted using Standardbred horses as a reference breed, mixed-breed ponies as a second group and Andalusian horses as a third group. This study will look at various management factors that may contribute to the development of obesity, equine metabolic syndrome and laminitis.
2. In a pilot study, horses in these groups were fed a fiber-based meal that included 1.5g/kg body weight of glucose. While breed did not affect glycemic response, the insulin responses of the ponies and Andalusian horses were significantly elevated compared to the Standardbreds.
3. In a 20-week project, horses fed a high-calorie diet containing a once-daily glucose load became obese, as did those fed a high-calorie diet along with added fat. Animals on a control diet did not become obese. Insulin sensitivity in the horses that were given added fat did not differ from those in the control group, while insulin sensitivity improved slightly in the group fed glucose. This result indicated that obesity by itself does not necessarily cause IR.
4. To determine whether a longer period of an increased insulin response would cause IR, two groups of horses were fed large grain meals twice a day while the control group did not receive these meals. Ponies and Andalusians showed a greater and longer-lasting insulin response than Standardbreds, indicating decreased insulin sensitivity.
Results to this point in the study suggest that increased insulin response and IR may tend to drive obesity in horses and ponies. Continuation of the research may shed more light on obesity and metabolism in equines.
Kathleen Crandell, PhD, is an equine nutritionist with Kentucky Equine Research in Versailles, Ky.
Hoof Nutrition Intelligence is brought to you by W.F. Young Co. (Absorbine). 
Like many significant achievements, Absorbine® grew out of humble beginnings—and through the tenacity of someone willing to question the status quo. In this case, it was a young woman in late 19th-century Massachusetts: Mary Ida Young. Her husband, Wilbur Fenelon Young, was an enterprising piano deliveryman who relied on the couple’s team of horses to make deliveries throughout the Northeast. Inspired by Mary Ida and Wilbur’s vision, Absorbine® has continued to add innovative products throughout the years — products used every day by horse owners around the world. Which is why, since 1892, we’ve been The Horse World’s Most Trusted Name®.
Click here to read Part 1 of the May 1, 2018 installment: Will using a grazing muzzle help me keep weight off my horses?
Click here to read more installments of Hoof Nutrition Intelligence.