If you have examined his leg good for any sign of a break or heat[which can mean infection] and both check out okay, then for a a sprain about all you can do is keep him confined where he isn't having to keep up with the flock or walk too much. I make a small pen inside the yard put food and water in there and keep mine in this, that way they can still be with everyone but aren't moving around too much giving the leg a chance to heal, then I put them into the pool a couple times a day with me right there to pick them up and out so they don't do any jumping down onto the leg to make it worse, water therapy is really a good way to take weight off the injured leg and also give the muscle a good work out, even if they just float it's giving the leg a chance to heal, and if you can get some Epsom salt you can also soak him in a warm water and Epsom salt. Mix it real good and then plop him into it. i like to use a dish pan because I can put the whole duck in and hold him there while he soaks, Epsom salt is also used as a laxative so don't let him drink the water. Or you can soak some cloths in the solutions and wring out just a tad and wrap the leg. ES is great at bring down swelling and helping injured muscles to heal. If you have some poultry vitamins to ad to his water this will help too. Of course if you have a vet that will look at ducks then I'd dif suggest taking him. Please let us know how he gets on. Thanks.
