Such a sweet lil thing, okay can you bend the leg like they were talking about in the link I gave you/ where you put the leg in the position just like it the little one was stretching it's leg out to the back like they do? in a normal stretch? they also take about using vet wrap[ sports] tape and taping the leg into a normal position but you'll need to read the entire piece about before doing it.
Some do, but I sprinkle on top of feed. That sounds like maybe the tendon. you might think about splinting in normal position according to the link I gave you.
Have you tried putting the duckling in some warm water to see how it uses it's leg? Half full sink and stay close by take out before the water cools, it is also a good way to do therapy and strengthen leg muscles. If you can take it to the vet then that sounds like a good idea.
I'd say a vet needs to look at it. is that swelling hard to tell when the leg is bent like that. I believe that is swelling I hope they can do something.The vet was booked out today, so will be heading there tomorrow instead.
I'll try him out with some water tonight
Bless it's heart hows it doing other wise ?
