Zesterra® is a 100% all-natural supplement for horses. It’s formulated to provide support for horses that are prone to stress or experience ulcers or ulcer symptoms. Zesterra® is a unique equine supplement that neutralizes excess gastric acid, encourages feed and water consumption and allows for greater nutrient absorption. It’s particularly helpful when your horse experiences stressful situations like hauling, foaling, heavy training or extreme weather.