Ive had chickens for abut 15 years and I have hardly ever lost any but in the last 6 months I have lost about 8 to 10 hens and I am looking for any help as to why they are dying. I have chickens from 1 to 3 years old. Whatever this is, it is only killing the young birds. They all seem normal, but within a week or sometimes just days before they die they start acting sluggish, tired, or slow. I had one bird have one swollen breast, but the others really didn’t show any abnormal physical features. I don’t know what else to say. Ask questions and I’ll try to answer them but this is starting to really bother me and I don’t know where to start.