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I'm Dr. Jaime and I'd like to help. I wouldn't be adverse to deworming these ladies if they are otherwise not well; especially if there is diarrhea, fecal pasting around the vent, weight loss or feathers missing around the vent. If there is a parasite burden it isn't helping if there is something else going on. With our elderly hens support of the immune system by decreasing parasite load is a good idea in my opinion. Other reasons older hens can have problems that resemble blockage can be reproductive tract disease, arthritis and kidney problems, so if the deworming doesn't help I would recommend a further work up with radiographs and blood tests.
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