Hi there just following this thread. If its any help, we have discovered a brilliant ProBiotic for dogs that we use on our 2 Labs. We just mix in a couple of scoops into their food each day. It has helped with loose stools (yuk ) and gas plus I think they have much shinier coats . Its from Tippy Toes Pet Boutique and we got it on Amazon for about $35 here is a link if it helps you
https://www.amazon.com/dp/B017WM4TSW