Instructions
Be aware that sickness in a duck can take many forms but they typically all create pretty much the same outwardly visible symptoms, such as, dull feathers, listless appearance, hunched up spine and general lethargy. Some illnesses however create virtually no preliminary symptoms whatsoever and the duck simply dies without much warning on the farmer's part. In cases like that, there is not much the farmer can do to prevent that death but he or she can prevent further deaths by quickly removing the corpse and disinfecting the area where it died.
Know that injuries to the duck's foot are easy to spot. The tell-tale limp is all it takes to make it obvious. But then you need to figure out why the duck is limping. It could be any of several things; a broken toe, sprained ankle, foreign object punched into the flesh or even bumble foot which is a parasite the duck picks up by walking in its own manure. This condition can be eliminated by simply hosing down the duck yard and washing away the duck feces.
Be aware that egg-bound ducks will act lethargic, appear miserable and will have an odd posture, with their posterior region nearly dragging on the ground. When touched, the belly will be hard and distended. She will be trying to push out the stuck egg. This condition can kill a duck, so it is prudent to proceed quickly to try and remove the offending egg. Pull back the edges of the vent until the egg shell is partially visible, and poke it with a small but sharp blade. The duck will not like you pushing on the egg while she is trying to push it out but you must do this. When the egg breaks, the yolk and egg white will run out and you must make sure that all of the broken shell is expelled as well so an infection does not set in.
Consider that healthy ducks will dance around, flutter their wings a lot and just generally enjoy living. An injured or sickly duck will do none of those things and will, in fact, simply sit and suffer in a very visible fashion. Sometimes you will notice a diarrhea type voiding stuck to the duck's vent feathers. This is not a good sign, even though most of the time duck manure is pretty sloppy. Normally it does not get on the feathers but when the duck is sick it will probably spend much of its time lying in its own waste matter.
Know that sometimes ducks will grab each other by the tips of the wings and this can, especially in ducklings, cause broken bones in the wings. If left untreated this usually means a wing will stick out at a bizarre angle for the rest of the duck's life. The broken wing can be easily mended however, simply by taping it to the duck's back. Unfortunately the duck most likely will not like this idea and will probably attempt to pull the tape off itself. Even if successful in removing the tape, the wing will probably heal much straighter than it would have otherwise.
How to Tell if You Have a Sick Duck
Ducks have very definite personalities and if one is acting differently than it should be it can become very noticeable. When they deviate from their normal behavior it can mean that they are sick or injured. Through observation you can tell what a duck should act like when it is well. You will know how it behaves when it is sleepy, when it is happy and when it is hungry. You will also know when it is hurt or sick.