A dog attacked my chicken, too. I asked how to treat it and this is what somebody said:
Electrolytes for shock (their biggest enemy after an attack) - a bit of Pedialtye or Gatorade in her water will do in a pinch if poultry electroltyes not on hand. If not readily drinking while still the mix is still cold (effectiveness issue), try spritzing some on cold watermelon or some other fruit they really like. Accomplishes hydration at the same time.
Quiet comfortable place to recuperate, not too hot and not too cold, with all needs close at hand. If she is happiest with her feather buddies that is fine, so long as they are not pecking at or otherwise pestering her.
She may become sore and not eat or drink readily, or seem depressed. 1 crushed baby aspirin (81mg) per cup of drinking water is a low dose believed by most to be quite safe (and roughly equivalent to the dose oft quoted on BYC of five 325mg aspirins per gallon of water). Since aspirin is a blood thinner it shouldn't be used during active bleeding or if internal bleeding suspected. Change out for a fresh batch at least once daily. After injury it is not uncommon for a bird to not want to eat or drink yet staying hydrated is crucial. Often, pain relief can go a long way toward inspiring them to want to drink/eat. I've sometimes had Metacam prescribed by a vet for inflammation/injuries and it can be effective.
Neosporin (with added pain relief ingredient) applied topically to wounds. Best to wash wounds first with 9 parts water/1 part Betadine.
(copied from the exact post)