I know that this topic has been addressed well on here, but here is my quandary: My girls, 2 plymouths and 3 barred rocks are one year old this month. They have been laying like crazy since Sept. I would say pretty early in their lay I started to get one egg per day that looks like it has been 'scratched'. It is also large and thin-shelled. Thinking it was a calcium problem, I added more to their diets. It did improve, but I also notice that every egg does have a little something strange about it shell-wise (a bump, now some are speckled, a fainter version of the scratches). My chickens have sneezed from time to time, but never have I seen any respiratory difficulty like what IB sounds like. They never slowed down laying, and the egg quality has remained the same. Here is the tough question: I am going to add to the flock soon and I am afraid that if they do have some sort of infection they might pass it along! Does anyone out there have any experience with this? Thanks so much!