I went on a 3 day vacation and hired a petsitter. The petsitter did a wonderful job, so I have no doubt that the injury is not due to her or her care. Anyway, I came back to find one of my indian runner ducklings can not stand. Everybody else is fine. I can't find any visible injury at all, not even swelling. This same duckling did something quite weird a few weeks ago, I'm not sure if it's related: all the ducks were scurrying out of my way, and he sort of froze up and fell onto his back and acted almost like his back was broken. I walked right up to him and picked him up and he did not fight it. I set him in the duck house and a few minutes later he was fine. The only thing I can think that has changed from before I left on vacation and now is that I introduced scratch grains into the diet and enlarged their area. Other than that... they eat a mixed feed that is comprised primarily of chick starter (non medicated), and then it's also got some higher protein show bird feed mixed in, and I also add in the dust and flakes of alfalfa that is in the bag once the alfalfa cubes for the rabbits are used. It's got just a small amount of rabbit feed pellets, oyster shell, and grit mixed in too. They also get a few handfuls of fresh picked vegetation from the yard (no pesticides or herbicides or fertilizers used). They are on the ground with plenty of water and their bedding is either cedar or aspen shavings. They have a shelter. I added some vitamins to today's ration of feed just in case it's something like niacin or other vitamin/mineral deficiency, but I am hoping someone can give me an idea that perhaps I haven't thought of.