TIL Marek's Disease kills chickens, it is preventable, but chicks sold at farm/ranch stores are usually unvaccinated
We recently had several 4-year-old hens die of Marek's Disease. Chicks can have this and show few/no signs until they die quickly as mature adults. It is completely preventable but chicks must be vaccinated as eggs or one-day-old chicks - they can't be vaccinated later. 1022
Most local farm/ranch/feed stores sell unvaccinated chicks to give buyers the "choice" of vaccinating, but because it's too late to vaccinate by time the chicks are sold, vaccinating isn't actually a choice. If you're buying chicks, please do your research. There are online places that sell vaccinated chicks but vaccinating is usually listed as optional. 881