This can sometimes be a one-time thing that never happens again, or it can be something that can sometimes kill a hen. One of the links given above reads:
"Be Wary of What You Read on the Internet
"A lot of the information available on the internet recommends an immediate death sentence and here is why I think some people say this. In a commercial chicken business, the bottom line is production and profit. Now I am not saying that the operators don’t care for the chickens or want them to be healthy. I am saying that feeding a potentially, seriously ill chicken would be counter productive to the goal.
"This is why I state over and over that we need to know the purpose of the information on the internet. Why was it written, and who was it written for. Information written for poultry production houses can vary greatly from a course of action a small flock owner can take with non-communicable health issues.
"What should a backyard chicken keeper do?
In the case of backyard chicken keepers and non- contagious illness, we can usually afford to take a few days to observe the affected hen, if we can even determine who laid the lash egg. Also, seek professional veterinary help if you feel you need it. No one can diagnose anything with one hundred percent accuracy, on the internet."