The context makes a lot of sense! You sound like a very supportive mom. You’re diving into the deep end of a complex hobby looking at a very complex sub topic where there is the intersection of science and supplements/care/opinion.
For now, I’d try to keep lots of hay in front of the horse, aim for a nice consistent routine, and wait until the next scope. As noted, I’d emotional prepare that there’s a chance you won’t have full healing as ulcers sometimes need multiple medications and an extended treatment protocol.
More broadly, ulcers are unfortunately common with these big beautiful not so great at surviving animals. If you’re at a competition barn with a lot of travel, there may be a real learning curve for what this specific horse needs. You listed a lot of great supplements and may find one or more helpful. The tricky part is that if you don’t have a reoccurrence it doesn’t necessarily tell you it’s working and if you have a reoccurrence maybe the supplements made them less bad than they could have been.
Once you have confirmation that the stomach is happy, I’d personally start with outlast and talk with your vet about how gastroguard may be used to support travel. Personally, I’d rather have my horses diet be 95% hay and then use the smallest volume concentrated source for vitamins and minerals to balance. If the horse is currently getting a large volume of grain, you could also ask your vet about increase forage (hay or grass) to offset calories and switching to a “ration balancer” or “vitamin and mineral supplement like California trace plus soaked alfalfa pellets”.
Keep asking questions and know that your horse is lucky to have landed in a family where they get to be loved on by a kid and have an adult as their advocate.
Best of luck!
