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: Could my overweight horse have an insulin problem?
By Eleanor Kellon, VMD
Since laminitis has always been with us, it’s no secret that overweight animals are at high risk. We now know that the vast majority of laminitis cases are caused by high insulin levels, known as hyperinsulinemia.
Does this mean that being overweight or obese causes insulin problems? It might seem that way, but the logic is faulty. There is an important principle in science which states “Correlation (or association) is not causation.” Observing that things occur together does not mean one causes the other.
Many horses that develop laminitis are overweight or obese and the vast majority of laminitis cases are caused by high insulin levels. Since the correlation has always been obvious, it didn’t take long for an assumption to arise that obesity is a laminitis risk factor and causes elevated insulin. There’s just one thing: It’s not true.
A study published in the Equine Veterinary Journal in 2015 reported on feeding horses and ponies a control diet or one designed to cause obesity by feeding either excess fat or excess fat and glucose. The weight gain did not reduce insulin sensitivity in either group. The study also clearly showed that insulin responses to oral or intravenous glucose have marked variation based on the breed of horses having a normal weight.
Another 2015 study followed two groups of Finnhorse mares on either native pasture or intensively managed improved pasture. After 98 days of grazing, the mares on improved pasture went from a body condition score of 5.5 to 7 and gained 145 pounds, but this was not associated with insulin resistance. If obesity isn’t a cause, why is more insulin resistance (IR) seen in obese horses — 25%-50% depending on the study versus 10%-15% of horses in general?
The answer is simple, as IR increases appetite and weight gain. Yes, there is an association between obesity and high insulin, but obesity is the result, not the cause.
This is more than just splitting hairs. If you think obesity is a cause, then weight control becomes a treatment and possibly a cure. When you realize it is a consequence, and not a cause, then expectations for results with weight loss become more realistic.
There are many benefits to weight loss and it should be aggressively pursued, but it won’t make IR go away. Approximately 50% of IR horses are normal weight.
Dr. Eleanor Kellon, a staff veterinary specialist for Uckele Health & Nutrition, has been an established authority in the field of equine nutrition for over 30 years. The owner of Equine Nutritional Solutions in Robesonia, Pa., she is a founding member and leader of the Equine Cushings and Insulin Resistance (ECIR) group, whose mission is to improve the welfare of horses with metabolic disorders via integration of research and real-life clinical experience. Prevention of laminitis is the ultimate goal.
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 Nov. 1, 2018 installment: Are certain laminitis issues related to certain hormones?
Click here to read more installments of Hoof Nutrition Intelligence.