Hens don’t go on laying forever. They are born with a finite number of egg cells and once these are used up, that’s it! Productivity declines as the hens age and generally hen keepers manage this in two ways. Some people choose to replace their flock as they become less or unproductive. They either donate their hens to willing adopters or dispatch them. Other people see the hens as much loved pets and keep them until their final cluck which can be as long as 10-12 years! Personally I sympathise with both views as I’m 50% pragmatic, 50% sentimental!
Whatever your view, I’m sure we all agree that a severely injured or poorly hen should not be left in pain or to suffer. Assuming all treatment options have been exhausted, there are a number of options: