A few weeks ago we had a unknown disease go though our coop. The following thread gives more information. https://www.backyardchickens.com/t/1128670/carriers-for-life/ Following suggestions from @heatherlaw and @Wyorp Rock, we sent two chickens away for a necropsy. Now after more dying and one with a leg problem. The poultry lab is finished and they have said it is Merrik's Disease. The vet said any new chickens should be vaccinated and that we should kill chickens that show signs. Has anyone dealt with the same problem? How did you deal with it? I am regreting getting the vaccines from the hatchery now, that's for sure.