So sorry for your loss. It can and does happen no matter what you do. I wouldn't say sickness is common though. Like I said before, you can be the best chicken keeper in the world, and sometimes it just happens. If you keep their area clean, good feed and clean water, dry, draft free coop and regular de-worming it increases the odds that it will not happen. Make sure you check regularly for lice/mites. Also if you ever get new chickens, always quarantine for 30 days before introducing to existing flock. Hope this helps.
