I think it comes down to your level of actual risk and risk tolerance. From what I've gathered, there were not chickens on my property for thirty some years, till mine that is. I considered the actual risk to be low while my tolerance is higher than most. I do not use medicated, nor do I ever switch them from flock raiser. I do not even have corid on hand, but the store is less than 5 miles away.You assumed right. I am not feeding medicated. Just Chickstarter 20%