BO not eating much and is super skinny.
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Valbazen 1/2 ml given orally, and repeated in 10 days. If you can't find it locally, you can order it online. If I were you, I would bring her inside for a day or two, and try feeding her by herself. She may be kept away from the food by higher pecking order chickens. I always place a couple of feeders and an extra water station where the more meek ones can eat and drink. You can give her some extra protein in egg, tuna, liver, or high protein game bird feed, and supplement some probiotics and vitamins.