Control of parasites should be primarily done by management. Keep the coop dry, remove the manure, break the lifecycle of the parasites. (I have more at my website.)
I've had vaccinated and unvaccinated for Marek's. There's a strong genetic component with who survives. Vaccinated hens can...
I'm so sorry about this. (I just got back on line after the stomach flu or I would have responded.) I'm very interested in the vet's necropsy (I do necropsies on my own birds. Took a workshop and am otherwise self-taught.) I'm surprised a city vet knew how to do a necropsy on a chicken. Did...