It is better to save the chicken and IF there is a secondary problem, have the actual time (I.E. the chicken lives) to find an underlying problem... if there is one.
I spoke by experience!
Okay. Not sure if anyone has answered the actual question or not.
This is a bacterial infection. It is quite common and can be treated over the counter. There is an antibiotic called Oxytetracycline HCI Soluble Powder. You can usually find it at your local feed store but can assuredly find it...