I'll post a few links to some of the products mentioned above so you can check out their ingredient list and feeding instructions so you can see if you think they are right for you:
Nature's Farmacy Dogzymes:
https://www.chewy.com/natures-farmac...otic/dp/153519
Vetriscience Probiotic products:
https://www.chewy.com/s?query=vetris...submit-button=
For the Vetriscience products, check out the ingredient lists carefully. Some contain only yeast (as the active ingredient), some contain only fermentation products, and some contain probiotic bacteria, which is the "classic" probiotic. If I wanted to go for the biggest effect, I'd choose the ones containing the probiotic bacteria, but check with your vet first.