I have a duck with what I believe is a slipped tendon. She was a year old when it happened (not sure how at that age) and we didn't catch it in time to correct ourselves (a vet is out of the question). She can't straighten that leg at all, but she gets around okay. The ends of her wing feathers are a bit tattered (she uses them to balance when she "walks") but otherwise she has been fine so far. Mostly just sits around the yard except to eat and drink. It's been over a year and she is still with us. Couldn't outrun a predator, but I don't have the heart to put her down when she is otherwise healthy. Amputation was not needed and I wouldn't have done it anyway. I would have culled her first.