This is Patch my 9 year old greyhound.
His stools have always been more or less on the runny side.
After some 3 years on the cooked diet, following vets’ advice, I fed him dry food for two years. The only advantage seemed to be the firmer stools – he never got used the new diet and always left at least half the portion.
His health was deteriorating and I decided to go back to cooking for him. The improvement was almost miraculous (after all, he was eating again) but then his stools got runny again.
A couple of months later, I discovered Bionic Biotic at Pets at Home, and, to my delight, almost immediately after I added it to his food, his stools became firm!
We are now going through the second bag.