I'd give her a good warm bath using cat-flea shampoo, rinse well and use a blow dryer to remove all water from her feathers. Give her a good exam while handling her. Feel her joints to see if they are hot and swollen. Look in her mouth, feel her neck, chest and back for lumps and bumps. While she's enjoying a day at the spa clean the coop, roosts and nest boxes and spray with an approved insecticide. Remove all old shavings etc and replace with new clean shavings. Evaluate her diet-she's not laying so she will not longer need to eat layer pellets and avoid scratch feed as that may cause gout in older poultry. I feed my old gals wild bird seed with occasional dog food (purina lamb and rice). Add Kale and fresh greens. They do well with sprouted seeds, too. Your senior hen might enjoy using ramps and her own roosting area close to the ground. My Senior Center has wide ramps with added traction, wide roosts low to the ground, soft, dry sand to scratch about during the day.
This hen is 11 years old. She no longer lays any eggs and there is no reason to keep her around except I have respect for senior citizens of all species. She has one sibling still with her and they enjoy living the good life.
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