I use Koapectate for my Boston that weighs about 22 lbs. My vet recommended it. I have a syringe that I fill to 0.5 or 1, just a very small amount, and then squirt in his mouth. He hates it but it works well. He seems to have a sensitive stomach.
you can use human imodium, if necasary, can give half for a 20-30 lb
i think you should first find out why the dog has diareah, and try to correct it, if you give him something for diarreah how are you to know if what you do helps
what kind of diarreah does the dog have, how long, and specs or anything in it, what color, smell, consistancy, if the dog is dehydrated? could be a number of different things causing the diarreah, they dont get it for nothing
Their is over the counter stuff but I would check with your vet what to usesand the dosagrs you give the dog is by how much the dog weights.