There is a cycle of aging that occurs in all species. As you get older, your body’s chemistry begins to change. When humans hit middle age, they find that their metabolism slows down, making it harder to lose weight and keep it off. The same can be said for the aging equine. When horses hit what’s considered to be middle age (8–18 years old) it’s not uncommon to see them become a little rounder in the midsection and act a bit sluggish, even when you think you’re providing a high quality nutrition plan. These horses may have developed equine metabolic syndrome, more commonly known as EMS.