This seems to cover most of the symptoms - thanks so much!
It seems to be limited to the Marans, so I will cull out that breed, it guess.
Thanks for the quick response, it really helps!
I have a flock of around 18 hens (mixed and BCMarans). For over a year now, there will be an occasional hen (i happens about every 2-3 months) that will all of a sudden go down on her legs. For a few days, she would wobble a bit and then she will just lay on her side and when she tries to exert...