If you need some more protection, like if you're traveling, gastrogard or ulcergard is good, but making sure your horse is getting enough forage is crucial to preventing ulcers- it doesn't have to be super high quality either. An older, stemmy grass hay is great for chew time.
Constant free-choice hay/forage is going to be your best friend when it comes to preventing ulcers. Saliva creates a gastric acid buffer, and it's really only produced when the horse is chewing. I use a slow feeder net with 1 1/2 inch holes when my horses are in
Ulcer guard(omeprezole paste), U-guard(daily pellet supplement), and I use a daily powder probiotic called G.U.T which is derived from licorice root and slippery elm bark(it works well for my horse) you can get all these supplements at smartpak😀
Bicarbonate! Can feed a handful at a time and it really seems to settle the stomach. We feed it with a handful of chaff about 20 mins before we ride. Much cheaper to buy and works wonders with some of ours
Omeprazole is a great med that can be used every few days (talk to your vet) to prevent ulcers. It is the cheaper form of gastroguard. Also Acid FX is great!I use both on nervous TBs and they do a great job!