Obesity in horses is a major problem in the United States. Many horses have equine metabolic syndrome, which enables them to gain weight even if they are not being overfed. The major concern with horses being overweight is that they are susceptible to laminitis, which is a painful foot condition. Laminitis can lead to founder, which can even lead to death. Obviously, obesity in horses - especially those with equine metabolic syndrome - is a serious condition. It is believed the reason these horses develop laminitis is because the horses are resistant to the effects of insulin, and high levels of insulin have been shown to cause laminitis.
Certainly the first line treatment is to change the diet to a low carbohydrate one to decrease weight. Some horses may need to be treated with a thyroid supplement to encourage weight loss quickly. Exercise is another possibility to help increase weight loss and decrease insulin sensitivity. To determine how much exercise is required to have an effect on insulin sensitivity, a study was performed in Brazil on horses that were divided into three groups. The first group was turned out only; the second was turned out and exercised with light intensity that included walking 60 minutes three times a week; the third group was turned out and given moderate exercise of 90 minutes three times a week. Results indicated that exercise intensity does have an effect on equine insulin sensitivity and turnout alone is not enough. Exercise did decrease blood insulin concentrations, which can decrease the chance of laminitis. Exercise can be effective in as quickly as 15 days. If you have an overweight horse, exercise of at least 60 minutes five times a week may help prevent laminitis.