Just killed our first chicken. Completely new experience for me and I may just continue to get it from the store. TMI below: I completely flaked on the knowledge that there would be a gullet. I should have made sure he wasn't fed for 24 hours. Dear God the smell. I'll never wash enough. I saw 3 mites. EEEK! Even tho the whole coop is dusted every 2 weeks. I washed that thing for 10 minutes after that. Obviously I'm probably going about this all wrong so link me before I have to throw this whole rooster out.
https://www.backyardchickens.com/forum/viewtopic.php?id=248648 ETA: If you found 3 mites then I'm sure there it more. You might want to check into something else to dust with. You might be dealing with creepy crawly for a few days.