Thank you, @Wyorp Rock as I had found a prior post of yours explaining some of this and dosage for Tylan 50 to reply to her and my internet took a digger for about an hour. I'm glad as you were hugely more thorough here than the one I was going to paste here for her.Sorry to hear about your pullet.
I would first clean the wound really well, trim the feathers from around the wound and re-access it.
An antibiotic may be necessary, but often with a very good cleaning a wound may heal fine without it.
For this, I would actually wash the wound with some warm soapy water since the powder is on there, work slowly and see how much crusty material will slough off. After a good flushing of clean warm water, trim the feathers from the wound. Swab the wound very well with an antiseptic like Hibiclens (Chlorhexidine) or Povidone Iodine.
Take photos please so we can see how deep the wound is.
Since this is under the wing, I'd lean toward keeping the tissue a bit drier. That's a warm moist environment. A good swabbing with the Chlorhexidine or Povidone Iodine a couple of times a day will help this heal up, unless I see something different when you post photos after clean up.
I've had this type of injury under the wing and yes, it's likely due to a rooster spur or claw cutting the skin. Yes, mine did smell like cooked or burnt chicken with a hint of infection too. Odd smell. With mine, daily cleaning worked fine, but iirc, my hen's wound was not quite that deep.
Tylan/Tylosin would not be my choice as an antibiotic for wounds. It's very good for treating respiratory infections, enteritis, g.i. infections, etc.
IF Tylan was the ONLY thing I had, then I would use it in a crisis. Tylan has a dosage range of 10-40mg/kg given 3 times a day for 5 days. Injectable Tylan can be given orally instead of by injection, it's known to cause injection site necrosis. There is a Soluble Tylan that can also be ordered online, it goes in the drinking water. Again, it's not what I'd choose for a wound.
Penicillin would be a better choice if you have to give an antibiotic and can't wait on shipping of Amoxicillin. Amoxicillin would be my first choice, but it does have to be ordered online or if you have a vet, they may be able to write you a script.
Penicillin G would be an appropriate choice for wounds. Dosage for Penicillin G is .25ml injected into the breast muscle 1/4" deep once daily for 4 days, alternating sides. You will want a 20gauge needle and small syringe.
Amoxicillin dose is 57mg per pound of weight given orally twice a day for 7-10 days.
You can order it online HERE.
