A vet will prescribe an antibiotic to treat a specific issue and they will specify the dose according to the weight of the patient. No, they do not need to be an avian vet, but if they have a profit oriented business, they may insist on seeing your chicken even if they know nothing about poultry before they prescribe medication.
Your hen may heal fine without it. See how it goes. Check on the wound and you will be able to see if it's healing. If she becomes overwhelmed by the infection, she will act lethargic and the wound will remain swollen. Then you can reconsider seeking a antibiotic.
Your hen may heal fine without it. See how it goes. Check on the wound and you will be able to see if it's healing. If she becomes overwhelmed by the infection, she will act lethargic and the wound will remain swollen. Then you can reconsider seeking a antibiotic.