While we are currently animal free due to young kids, we did have a bullmastiff who benefitted greatly from high quality probiotics. We fed him the same ones we take and now also give our kids. My in-laws have a Boxer with GI issues due to previous owner abuse and we giver her probiotics when we dog sit. She always does much better with us due to this, but my in-laws don’t believe in witch medicine. Since most of our immune system is in our gut, would this not hold true for pups as well? Anyway, there are no side effects so what would it hurt?
Parvo dehydrates the dog; vomiting and diarrhea wouldn’t let the food stay in long enough right now, but that would be great afterwards. Recovery can take a while and anything to help the puppy get back to normal would be a plus.