@Kimberlie I use Kaffmann's Stress Formula. I get it in a 5 lb. bucket.It is great stuff,used their products for years for my horses and dogs. It is a powder,which I sprinkle on their food. It is probiotics. I also give them yogurt(2 tbsps) at bedtime. When Carlie was sick, I got some Nuvet Plus for her, and I think I am going to continue with that also.
My dogs never have gas.