I have the same problem and have a 3 step solution that has been very effective. I see this problem with about 5 to 10 percent of my flock of Pekins. Try the following:
1. Isolate the duck in a large tub, big enough for the duck food and water, but not big enough for the duck to walk, immobilization is key.
2. Give the duck an anti inflammatory 3 times daily.
DO THE MATH ON DOSING!! You can also check the MERK PROFESSIONAL VETERINARY REFERENCE for more information. I used children’s Motrin 100 mg per 5cc suspension. They make other strengths so be careful you do not overdose your bird. This gives you a dosage of 20mg/cc. Using a dosing chart for ducks I calculated a .22cc per pound. So if your duck weighs 6.6 lbs the dosage would be 1.452cc 3 times a day. The dosage I calculated for my ducks was 2cc 3 times daily. An oral syringe has been an effective delivery system. You should see improvement in 24 to 48 hours.
3. Have the duck swim in 75 to 85 degree water daily.
The combination of swimming, keeping the weight off the leg and anti inflammatory has proven effective for me. BUT I AM NOT A VETERINARIAN SPECIALIZING IN BIRDS. This has worked for me, I always recommend contacting a professionally trained specialist. Good luck.
Just read about the stomach. It sounds like the duck has wet feathers she can’t properly clean and re oil. Make sure the duck has clean dry bedding, can reach the oil gland and the feathers in question. Also when letting the duck swim you may want to dry the bird with a towel and a hair dryer on a low setting. Duck feathers only repel water properly if clean and oiled by the duck.
It also sounds like you fed and cared for the duck properly. This problem only occurs for me rarely and with heavier birds, 6 to 8 pounds. Good luck hope this helps.
