Sorry. I misspoke here. The vet and I were discussing eggs without shells when she said this. She said if they are on a layer ration, a calcium metabolism issue is unlikely and that it’s almost always from E.Coli ascending from the vent. She also said it’s almost always cancer or a reproductive infection that “gets them” (hens) , but I think that’s pretty common knowledge for chicken keepers....the avian vet said hen illnesses are almost always caused by E.Coli ascending from the vent. I might become a neurotic butt cleaner.