We kept a duck for the first two months and then took her to a local pond. Now, 2 months later, I went to see her and she has an injured left leg that she doesn't use at all, just drags it along and her back looks mangled. No feathers around oil gland and most are missing up her spine. She was hiding in a bush at the park and flies andants were all over her. Bright her home, gave her clean water and food and a bath, and she seems to be in better spirits now but still not much energy and obviously can't walk. She scootS around the cage when she needs to but doesn't go more than 5 feet. In the bath she flapped her wings like normal to dry off, but never dunked her head repeatedly like usual. Thoughts on what happened to her back? And is that what's causing the leg injury?
She was definitely attacked by a predator, maybe a dog. I'm glad you took her back, put please do not bring her back to the park again after this if you manage to get her healthy once more. Domestic ducks do not do well at parks, as you have seen. If you can't keep her, please find someone who can and give her to them.
Now, onto the wound. Firstly, since it was covered with flies when you found her, you're going to need to keep a sharp eye on it for flystrike - maggots in the wound. In fact, make sure you check her good all over under all her feathers for other wounds too and check them for flystrike as well.
Clean the wound off with water and apply an Espom salt compress. This will help with any swelling and will help draw out any infection if there is any.
After that, apply neosporin to the wound. Repeat this process daily.
You may also want to let her swim in a warm tub of water each day to exercise her wounded leg. If we're lucky, it's just soft tissue damage and will heal over time. Worst case scenario, it's a break or, due to the position of the wound and where it looks like she was attacked, spinal damage.
Does the leg feel hot to the touch?
Really the best thing to do here if at all possible is to get her to a vet and have x-rays done to see what's really wrong with the leg.
The leg doesn't seem hot to the touch, feels the same as the other. Unfortunately, the leg just dangles there but doesn't seem to be causing her pain, it just makes it hard for her to get around. She's eating and drinking a little, which I"m sure is helping her. We let her swim in the bathtub this morning, but she didn't do much swimming, just floated around. We splashed water on her to make sure it rinsed her off good and then she preened as good as she could once we took her out. We soaked her last night as well when we got home with her and quite a few small bugs fell off and were in the water. We did this until we saw no more bugs, so hopefully we got everything.
Hopefully you're right about her leg. It's not at a funny angle or anything like that, she just doesn't seem to have any control over it. I think we're going to take her to a wildlife rescue tomorrow and let them take care of her and hopefully find somewhere she can go and be safe if she's able to heal.