I personally know of a racehorse trainer who treated ulcers in his stable with mastic gum. He uses a small maintenance as preventative. There are some studies that suggest H. Pylori doesn't cause ulcers in horses, only humans. That theory has since been disproved, as they have found proof that it does indeed burrow in the stomach lining and cause ulcers. "Another known cause is a specific bacteria – Helicobacter Equorum (H.Equorum).[v] This bacteria causes ulcers by creating actual physical damage as it burrows into the lining of the gastro-intestinal tract. While the damage caused by H. Equorum is well known in humans, as Helicobacter Pylori – it is a known cause of stomach cancer – its existence in horses is only recently discovered, and how it is transmitted to horses is unclear." http://www.stanceequine.co.uk/horsec...er-Syndrome-18
I don't agree with the treatment, as antibiotic therapy has not been effective in completely treating. Symptoms come and go; it becomes a cycle.