There are physiological differences between humans and horses. For example, horses don’t produce high levels of ketones, even when starving. Horses with EMS are not at high risk for cardiovascular disease the way humans are. They develop laminitis instead.
Despite these and other differences, the central need to limit simple carbohydrate intake to control insulin is the same for both. Simple carbohydrates are things which trigger an insulin response – small sugars and starch.
It has been proposed by some that the glycemic index matters more than the total amount/% of carbohydrates. This long term human study shows the total does matter:
“Another study randomized patients to a low-carbohydrate ketogenic diet (less than 20 g per day with no calorie restriction) or to a low–glycemic index diet (55% carbohydrate restriction of 500 kcal from baseline) over the course of 24 weeks ( Nutr Metab [Lond]. 2008 Dec 19. doi:10.1186/1743-7075-5-36). Between baseline and week 24, the mean HbA1c fell from 8.8% to 7.3% in the very-low-carbohydrate diet group, and from 8.3% to 7.8% in the low–glycemic diet group, for a between-group comparison P value of .03. In addition, 95% of patients in the low-carbohydrate diet group were able to reduce or eliminate the number of medications they were taking, compared with 62% of patients in the low–glycemic diet group (P less than .01).” [excerpt from article on Medscape]
Again, ketosis does not occur in horses. Horses get their replacement for carb calories from fermentable fiber, not high fat.
The first step in the management of a horse with metabolic syndrome is the controlled simple carbohydrate diet – 10% or less combined sugar and starch. On a laboratory analysis, simple sugars is ESC. Starch is listed as starch. If sound, provide as much exercise as possible. Most cases respond very well to this approach.
Eleanor Kellon, VMD