It had botulism. Botulism breeds in warm areas . It begins to grow in the ground and may be caused from being in the heat (in a trapped area.) It is spread by flies, but it's botulism c ,meaning it won't hurt humans and is common among ducks.It can also receive the disease through cuts and, it's airborne. So move it away from the infected area. The best you can do is feed it a whole lot of water and hope to flush it out. The first symptoms are slow moving legs when you pick it up. The paralysis often seams to start in the joints. It is often too late when the neck bends backwards. I know from experience. They will most likely have diarrhea and won't blink much.The bacterium Clostridium botulinum produces toxins that are dangerous to ducks. Colonies of this bacterium grow in stagnant ponds and in other areas where organic matter is decaying, such as near animal carcasses. The toxins produced can cause ducks to lose control of the muscles in their legs, neck, and wings. You will see the duck’s neck go limp, which is why this is also called limberneck. The affected duck will also be unable to swallow. Avoid poisoning by keeping ducks away from stagnant water, especially in hot weather when the bacteria grow the most. The duck may die rapidly, but you can attempt an old treatment. Give the duck water with one tablespoon of Epsom salts to one cup of water. Administer it with a syringe (not with a needle) because it cannot swallow easily.
