Sounds like to were able to get to them quick which always is good. Keep the wounds clean and make sure to keep them on as clean of bedding as you can while they are healing to keep nasty bacteria out, Rinsing in a saline wash and using something like triple antibiotic on the wound will help. Main thing is watching for infection. Keeping them on clean towels might be best to keep anything from sticking to the wound and if you can clipping feathers back so they don't get caught in the wounds as they heal.
Also reinforce the pen they were in predators are notorious for finding ways inside which means they will even climb. And most likely what ever it was will be back.
Ducks are extremely good at recovering if given good care. I'm sorry this happened.

Also reinforce the pen they were in predators are notorious for finding ways inside which means they will even climb. And most likely what ever it was will be back.
Ducks are extremely good at recovering if given good care. I'm sorry this happened.
