UlcerGard (omeprazole) Oral Paste for Prevention of Gastric Ulcers in Horses is the only product that's been approved by the FDA to prevent equine stomach ulcers. UlcerGard is a non-prescription preventive for Equine Gastric Ulcer Syndrome, a painful condition that can reduce your horse's performance and can even lead to death. UlcerGard contains omeprazole, which suppresses acid production in a horse's stomach.