My collie gets diarrhea anytime he ingests something other than his regular food. Heartworm medicine, diarrhea. Dog biscuit from the vet, diarrhea. You get the picture. I have two tubes of this on hand at all times. It works. Usually in the first dose. He doesn't like the taste, but my other dog will lick it off the floor if the collie spits it out (which isn't easy, it sticks to the mouth.)