I went into this past winter with a small flock consisting of nine Leghorns, four EE's, four red sex link, and two Black Jersey Giants. The birds were all one year old in February. I am now down to 7 Leghorns. As near as I can determine both of the birds I have lost succumbed due to hemorrhage as a result of laying one or more gigantic eggs. (Today's egg, shown in the photo below, is an astonishing,, six and seven eighths inches in circumference.) I have raised chickens for many years and do not remember having had this problem in the past. All I can think of is that perhaps it is this strain of Leghorns - no pun intended.