I posted earlier but after reading on chicken contagious diseases, this looks to be much more like avian encephalitis than coccidia. I have a 2wk-old partridge plymouth rock chick that is suddenly unable to walk. She is the only chick exhibiting these symptoms (I have 8). Yesterday I noticed her acting strangely, with her toes all bunched together and pointing forward; she walks on her hocks when she has to and this morning seems unable to stand on her feet at all. When I picked her up and set her back down, she wobbled and fell to a lying position. She then crawled over to the feeder and started eating. She will drink when I put the water directly in front of her. Her breathing appears to be labored as she takes large breaths, but she is not wheezing or coughing. Another chick has watery looking eyes and is not quite listless, but not active either. This chick has not grown nearly as fast as the others and while the rest have nearly fully feathered wings, she has only grown in the short feathers and has yet to sprout tail pinfeathers. I have isolated these two chicks together in a quarantine brooder (cat carrier). They are eating and I have put electrolyte water in their bowl, not wanting to unnecessarily medicate them for the wrong condition (I purchased sulfadimethoxine powder earlier in case of coccidia). The other 6 chicks are in an XL plastic dog crate with 3" sawdust, which I just changed. I clean the waterer every day and have added electrolytes to the healthy chicks' water as well. The only guess I have for the source of this illness is that I took them outside on Saturday and let them scratch around for an hour. I am not aware of the use of any pesticides or herbicides and no fertilizer or other lawn treatment has been applied in the past month at least. I certainly hope that letting them out this young did not cause this illness... I would feel horrible if I had to cull these 2wk-old babies. I'm keeping their quarantine brooder as far away as possible from the healthy one and the others certainly won't go outside for a while until I'm sure none of them are sick as well. Any ideas or suggestions for treating these chicks? Or other ideas for what this sudden-onset illness could be?