I have had 3 chicks now that come down with what I would almost consider Marek's type symptoms.........but recover within a couple days. A while back I had a little olive egger pullet that was very wobbley, kept just sitting back on her butt....would lean and sway when tryin to stand. I separated her and after a couple days she seemed to bounce back and has been fine since. A few days ago I moved a bunch of babies in the brooders.........one of the buff brahmas in the outside brooder (who had been there a couple weeks) was found just laying on her side against the back wall of the coop, unable to stand up or walk. If i stood her up, she would flail and tip over backwards. Completely uncoordinated. She had been in this coop for a couple weeks, but i had taken out 20 older chicks and added 20 younger chicks the night before these symptoms appears. One of the light brahmas in the inside brooder...failure to thrive chick, is still all down even at 4-6 weeks.....just a few wing feathers....but I found her upside down in the brooder and unable to right herself. Day after I had moved a bunch of chicks around. She had been in that same brooder setup for weeks but gained some new roommates. I moved both the buff brahma and light brahma to their own brooder with heat lamp. The light spent most of her time crouching...the buff spent all her time sprawled out on one side, as she was unable to stand or sit up. That was day before yesterday....as of last night, the light brahma was doing much better. Walking around and pecking for food. As of today the buff brahma was back on her feet and able to walk around. Not 100% but considering she couldn't even sit in place or stand 2 days ago, she is doing awesome. What could cause this? Chicks to be wobbly and have no balance, unable to walk or stand, just falling over and not being able to get up. On a sidenote, the olive egger and light brahma chicks had never been outside the brooder when these symptoms showed up. Everything else is normal, food, water, eating, pooping.