Maybe I made a bad problem worse. I have 4 chickens right now. One is a broody pekin, two are isabrowns and one is a little bantam belgian duccle. A couple of months ago we managed to "save" one of the isabrowns from internal laying, but ever since we did that, she's become really aggressive toward the belgian duccle (the isabrown was aggressive to begin with but the vet treatment might have made it worse). Today I had to save the belgian duccle from the isabrown. She had the feathers on the back of her head picked off, and there was a bit of bleeding there, as well as on the comb. We put the isabrown in solitary confinement (which I was a bit reluctant to do) and held the belgian duccle until she calmed down. She's now eating and grazing with the other chicken, but still in a bit of shock. Now I don't know what to do with my aggressive isabrown. I have a feeling there was some testosterone in the drug the vet gave her for the internal laying. We can't sell her, because she doesn't lay anymore and the drug she was given will only last 6 months (well about 3 months from now).