first thing that comes to mind is--worms? coccodia? mites? I'm sure others will have more ideas.

I agree with cerestone....can you give us more info? What breed, how are they housed, what are you feeding, etc. If you click on my 'My Page' link there is tons of chicken info there that may help you. I know how troubling it is to have mysterious problems like this. :(

Velvet ~:>

Look at the comb. A pale, whitish comb is a good indication of roundworms. Worms will certainly suck the nourishments from the bird's intestines and cause the characteristic "wasting" effect. Usually the ones already too thin and weak will die anyway, but worming the flock is a very good idea for all the others.

She actually seems better. I don't normally have one pull out of it when they start doing this. She is a new chicken to the hen house. A yellow Buff. I did worm them right after they arrived. That is funny you mentioned the pale combs. I was told something totally different. I was told a pale comb means they are not laying at the time. Dark red combs mean they are laying. This seems to be true as I have noticed only the dark red combs in the nesting boxes trying to lay. I use the pale eye lids with my goats to check for worm over load so I suppose this would work for chickens also with the combs. How often should chickens be wormed?

Okay, I'm with you on the pink vs. red combs, though tha's not always true, either, but can be a good indicator if vents are not checked. What I'm talking about in a wormy bird, is a very pale, almost white, comb. It's beyond pink. If you see that, pick up the bird and it will be noticeably lighter than the others. If loss is only 1/4 to 1/3 of normal weight, there's a good chance of saving the bird. However, often as I check pens day to day, I don't find a victim till it's literally down and dying. In a really large flock, this will happen. If a bird is picked up and has no appreciable weight, kill it immediately and destroy the carcass. Medicate the balance with both an antibiotic and a wormer.