I was going to say we lost two chickens at the weekend, we didn't loose them they died. The two light Sussex. Post mortems showed they had egg peritonitis and inflamed oviducts. They had not been laying for a while, one had been laying the odd shell less egg. We had kept them as we felt that it was unreasonable to kill them just because they weren't laying. I think we may see things differently in future as they could well have been in pain for a while but not showing it as they are prey animals.
The cause of egg peritonitis is not always clear. In our case I suspect the trigger was Infective Bronchitis which one of our chickens died of in the summer. I believe it is very infective, and if one in your flock has it they all do. None of the others in our flock showed any symptoms.
Infective Bronchitis affects the respiratory tract (airways) but as the oviduct has a similar membrane structure it can also be affected and the only sign is altered egg laying pattern. I think all of ours probably were affected as the egg count has been down all summer. I had put it down to the heat.
Not surprisingly the loss of two out of 7 of the flock has caused significant changes in groupings and sleeping arrangements. It is starting to settle out now, and has left us with a free hen house. So I have ordered 4 ex battery egg laying chickens to see try. They are coming mid November.