One of my hens has recently been showing signs of gapeworm but on reading a bit about the peritonitis I feel it may be one or the other. She is a Sussex and seems generally happy in herself but is the largest of the hens and weighs quite a bit. She tends to walk with a limp rather than a waddle but has a very bald and sore looking behind. It also seems quite inflated. Recently she has started making a very odd noise which I can only compare to those toys you buy kids that are plastic tubes that make a weird noise when you tip them to the side. A sort of last bit of breath croak. She stretches her neck right out and her breathing seems very laboured. It seems to have been worse today and she has spent most of her time laying down. I've heard that double yolkers are common with egg peritonitis and we have had a few of them recently. Really hoping it not as it would be a shame to see her go. She doesn't have any runny nose or discharge around her eyes. She sleeps on a mix of sawdust and straw when not on her perch and the other hens seem fine and healthy. Thanks guys.