I did when they first came from the hatchery. I understand that anxiety will cause it. Is he being picked on? Or has he been with you only a short time? Right now, at 5 weeks, they're pretty clean. I think it was mostly the first 2-3 weeks and even then, I didn't wash them if their butt was clear enough to poop. I did cut off bulky pieces, but most of the time, the vent was clear , not stopped up. Only had that on a few of the chicks.