one hen has a 2" diameter black , circular 'rash', and in the middle is a fairly large (3/4" high, a small child's finger in thickness) growth. it's just an inch or so from her vent. we just separated her to see if shes laying or not. photo probably isnt much help. her rear end is a bit messier than usual. the neighboring farmer suggested we cull, but they are sorta pets... i'd hate to do that.