Mostly because I've never had chickens long enough to see them jolt. (grins sheepishly) Plus, I did have trouble a few years back with a major mite infestation that killed a number of my hens, starting with a Welsumer who looked all fluffed up and then just keeled over after a week or so.
The...
I have a 9 month old Welsumer hen who just started losing a lot of feathers. Weirdest of all, they have mostly gone from her head and neck, stopping at a perfect line around her neck so that it looks like she got her head stuck in a contraption and backed herself out, removing all the feathers...