I logged in tonight looking for answers to the same question, except mine - unfortunately - are post mortem.
I purchased 1 dozen chicks from
TSC (6 Buff Orps and 6 white Leghorns) On 6 April. All was going well, noticed that one Buff & one Leghorn were a little smaller than the others, but still vying at the feeder and waterer. Last evening when I came home to feed, clean, cuddle & water I noticed the leghorn standing in the corner of the brooder, facing the corner. She looked like she was in time out.
I removed her, cuddled her closer to the heat lamp, poured out some feed, tried to encourage a little sugar water, to no avail. She seemed REALLY sleepy. Sleeping standing up, in fact.
I realized at this point it didn't look good, so I tried to keep her as comfortable as possible in a separate area of the brooder. While handling her she had one small defecation that was fluorescent yellow. I knew it was just a matter of time then, but didn't know why.
My instincts were correct, this morning when I came down she was dead. I'm watching the rest of the flock now for any signs of illness, but they are nearly double in size from what she was, so I can only assume it was failure to thrive, and something NQR that wasn't meant to be.
Any ideas?