Niacin deficiency in older girls

[pilotmuffin]

I have a pekin duck that's about 5 months old who has definitely signs of niacin deficiency. We didn't really notice it until a week ago. Her legs are bowed and she has considerable swelling around her "knees".
What can be done to treat her at this point? She gets around ok but is definitely having trouble.

 

[Miss Lydia]

Best treatment is liquid B complex
https://www.backyardchickens.com/threads/niacin-deficiency-in-waterfowl.1367557/
I'd also keep her from overusing her legs right now with the swelling going on. Nice soaks in the pool or bathtub can help take pressure off the legs and help keep the muscles from getting weak. Be sure to keep her from jumping down from the side of the pool.
Pekins grow so fast [meat ducks] that they have more issues with their legs than other breeds many on here that have Pekins keep the niacin going their whole lives.
I'd get the liquid B complex ASAP.