septra dosing for injured pullet?

[Fermatamama]

Hi all, new here and not sure I'm posting this correctly but I need some expert advice, please. I have pullet with a significant injury to top and back of her head where the others have pecked her. I thought she was dead but she is breathing, will respond to touch and sound and is taking water from a needle less syringe. I have cleaned the wound and have her isolated. Would septra be safe to give her to help prevent infection, and, if so, what is the correct dosing schedule? I also applied triple antibiotic ointment. Thanks for any suggestions!