It would be the presence of a disease within the population.
I'll give a very simple example. Let's say there's a pig barn with 2,000 finisher pigs. The producer goes into the barn. They have a prescription, and they have a protocol to treat pigs with streptococcus suis with injectable penicillin. They go into the pen, and they see a pig with clinical disease. They treat that pig. If the other adjacent pigs in that pen are showing clear signs or unclear signs, they can also be treated preventatively for that same disease.
There's a clinical push in the presence of disease.