I start by plucking all the feathers on the swollen part, clean really well with chlorhexidine, lay hen on her side, insert needle as shown in pictures above. When properly placed the fluid should start draining out. Then I attach the syringe and remove 30ml, remove syringe only, empty contents of syringe, repeat until fluid is drained.
Drained several hens and usually get about 500ml from each. One should only do this if they are 100% sure that the swelling is fluid. One should also know that there is a risk of introducing bacteria to the abdominal cavity, puncturing intestines or other organs. The antibiotic I use is Baytril.
-Kathy