I don't give him probiotics, but I do let him lick my greek yogurt bowl. Just like me, if I haven't had it in a while it throws him off. but if we eat it regularly our guts adapt after a week or so. I think if I remember right from reading the probiotic label my wife takes it say's something about disrupting your gut at first. Probably wouldn't hurt to treat some carrots and/or broccoli to go with it (to feed the new microbes) - that's the only two treats I use everyday.