Predators are getting bold.
Electrolites, save-a-chick, always a good choice.
Other than lost feathers, is the flesh torn much?
If so, the topical may not be enough and secondary infection may occur.
Lizdeal might be able to give you guinea antibiotic dosage,
I've been impressed with her knowledge.
A byc search should also help come with it.
With injury, I'd be in here asking myself - and have.
Had a turkey polt scalped last year and was freaked.
Did the same as you have, seperation, topical, s-a-c, boiled eggs - and that purple kote spray before returning to comrades once out of shock
(keeps the others from picking at red wounds) .
It lives yet so they can heal and go on just fine sometimes.
I've also had some that were very damaged by attack I put an end to thier suffering.
Owls, coons, coyotes, foxes - busy, busy varmits!!!!! Lot of us are having problems now. Awful business. Sorry you're getting it too.
Has the attacking dog been dealt with? Any security issues that need to be addressed to prevent future injury?