I'm new here. I have 4 Silkie roo's but am new to ducks. I have 8 ducklings...2 Pekin, 1 Cayuga, 1 Swedish Black, 1 Swedish Blue, 1 Rouen, 1 Golden 300 and 1 Khaki. This past saturday, 1 of my two week old Pekins went suddenly lame...couldn't walk normally, was falling back on his heels, off balance, sitting down a lot, etc. I rushed him/her to the vet where an x-ray was done but turned out to be normal. A fecal float was done and was negative for parasites. I suspected a niacin deficiency, but the emergency vet did not agree. She said that because of the duckling's diet (Mazuri waterfowl starter with some Purina flock raiser mixed in and lots of peas, dark leafy veggies, some fruit and cheerios along with brewers yeast supplementation) that there was no way the duck could be niacin deficient. After no improvement, I called my parrot vet who agreed to give a B complex injection yesterday afternoon (monday). My avian vet said it could be perosis (slipped tendon (s)). In which case there is apparently no real treatment. Monday night, after getting home from the vet, the duckling started acting paranoid. He was panicked and every few seconds would try to jump up and run around like something was chasing him (he couldn't really run due to his lack of strength in his legs, though). This went on for several hours. I put him in a small brooder for the night so he didn't hurt himself. This morning, the paranoia was gone but his condition was otherwise the same. I'm starting to see a noticeable size difference between this duckling and the others in his group. He eats and drinks, but not as much as the others because he has a hard time getting around. The symptoms seem to be classic niacin deficiency from what I've researched. He also seems very sleepy most of the time. Seems depressed. I'm totally at a loss. I'm making sure to feed the duckling morning and evening on his own so he gets enough food and I've added even more brewers yeast into his diet but nothing seems to be helping. I don't think he is in pain and his crop and digestive system seem to be working fine. I'm swimming him everyday, but he is pretty much uninterested (and he used to love it). Does anyone have any thoughts? I really want to help this little one get better but I don't know what else I can do at this point.