Last summer we had a few hens from a local breeder get sick and die. I sent one off for a necropsy to make sure that it wasn't Marek's disease. The results came back negative. About a month ago we had a healthy rooster all of a sudden get weak in the legs where he could not walk and he eventually died. Then last week a five-month-old cochin pullet started limping on one leg. She is eating and drinking perfectly fine except for the limp. I went to our local farmer's co-op and they said to try treating her with tetracycline in case she something that the other rooster had. I also started giving her a vitamin and electrolytes supplement. She is not getting better or worse. Another thing about her is that she is much smaller than the other hens wet got at the same time as her. I guess it's possible that she just injured her leg but it scares me because it seems like the others we have lost started with leg weakness. I just noticed that another five month old Cochin I have is laying around a lot today. I may be being paranoid but I don't want to lose any more. Any ideas on what this could be?