So sorry about your girl. It's hard to lose them. Euthanizing isn't as bad as it seems. Hard on me emotionally, but not hard on her. She seemed to relax from the pain relief, then relaxed more with the sedative, then fell asleep, and then slipped away. Whole thing took about 8 minutes, so plenty of time to "love on" her..
If it was e.y.p. - I am reading that it's more common in production-heavy breeds. Is this a condition that I can avoid by not buying from hatcheries/TSC?
It is the breed rather than the place purchased. You'll have to do some reading on-line, but the "dual-purpose" breeds seem to do better, since they don't lay as many eggs. My Ameracaunas and Black Australorps have been very healthy. They lay well and molt every year. I think the frequent molting/replenishing nutrients keeps them healthier. My Rhode Island Reds are also very strong, but don't molt often. It was the Golden Comets from a neighbor that have died from egg yolk peritonitis. I have one left, and I am keeping a close eye on her... seeing that she gets plenty of calcium. She finally molted about a month ago (at age 2 1/2 yrs), so I hope she will be ok for several months.