I feed probiotics to my horses, my dogs, and my husband daily. Its just good all the way around for us.
My horses feed is fair, but they have been in a bad way lately. So I feed it to them for their gut. My dog tend to get stress diarrhea, so I feed it to her for that. My husband has IBD, and well, its for that.
I notice when my family is off them. (IE I run out...) So I keep them on it.
~*~Never approach a bull from the front, a horse from the rear or a fool from any direction. - Cowboy saying~*~