What causes pasty butt? I recieved the last of my chicks on Thursday and last night I had to clean every single one of their butts! Some were so bad I had to soak them to get the poo off. They liked the warm water soak, didn't like the picking off of the poo too much. Then I blew them dry on low and stuck them back under their light. These are my third group of chicks this year and none of the others had pasty butt. Oh, they are partridge cochins......the others were BRs, arucanas, 2 silkies, 2 (now 1) polish and a RIR.