Have you checked for worms in case thats the issue?
Yes you can, there is ancedotal evidence that it minimizes tumors. I did that with my flock and any incoming no matter the age. My oldest mareks positive was a 16 year old silkie, my losses to mareks dropped significantly. You can get the...
Old post, but dont always assume mareks, get fecals done, check for mites and start vitamins. My flock is positive and i vac any incoming since there is ancedotal evidence that it limits tumor grown. My deaths have dropped considerably. Check here for live testing...
Well I wouldn't recommend a metal shed, yes I've never had predators other than snakes, but oklahoma summers make it an oven. So you'd need a way to cool it.
I would definitely think nutritional. Do you have any nutradrench or poultry cell? 0.50 mg morning and night directly on the beaknor on a treat, see if it helps. I'd also send a fecal to the link I posted.
People jump to0 fast assuming mateks. A friend had a bird the vet thought mareks, euthanized, necropsy came back as a heavy worm load. No mareks. So I'd put that on a back burner for now.