For the last two or three years I have been having an odd issue in my flock. I'll begin by saying that I have done research on marek's and I know there are different strains. We don't have the money right now to pay for a test to be done, and if my flock has the disease then probably 90% or more seem not to be affected by it, so the marek's isn't the issue. It's the fact that the birds that do get it seem to have a supressed immune system caused either by stress or genetics. I want to know how to avoid this or breed out of this.

We had a flock 6 or so years ago that had two cases of this in standard birds, but then we went without chickens for a few years. We got some new ones and there were no issues for at least 3 generations. I did my best to avoid any inbreeding or unhealthy genetics (I am creating an egg-laying bantam that is hardy and friendly). Anyways, in this generation there was a white bantam named Amber who had dark skin, no crest, and feathered-feet. She was raised with 3-4 other chicks, but when her mother began to "wean" her at about 35 days of age she began to limp. Thinking it was an injury, we tried to set the leg, but this only made it work. She couldn't stand, dragged her back legs, and could do little besides throw her legs around widely to try to walk. She had to be put down.

The next chick was Augie, and he was a large white bantam mix with light skin, no crest, and little to no feathering on his legs. He was about 47 days old when he developed symptoms. Trembling legs, walking with straight legs (no bend in the knee), knee bending the opposite direction, doing the splits, tripping and slipping, stumbling, sitting while eating, and eventually he could no longer stand and was having trouble breathing. We tried providing vitamins, high quality food, plenty of water, rest, warmth, ect but none of it worked.

Two chicks named Irons and Ivory developed Progressive Paralysis after a bad attack from another hen. They were around 50 days of age, and healed from the wounds, but their immune system was weakened. Their third sibling did not get the condition,and Ivory almost survived it but was attacked again. Both had to be put down. One was white with light skin and the other was white with light skin and silkied-feathers.

Blaze lasted 58 days before he had to be put down from the condition. Began with the typical flapping while walking, trembling legs, standing tall, slipping and doing the splits, bending over while eating, chirping when trying to keep up with siblings, difficulty staying on perches or gripping, ect. I let him stay out with his family until he could no longer walk. The issue seemed mainly in the legs, not the wings, lungs, head, ect. He was a Paint mix with no crest or feathers on the feet.

Degotoga, DaVinci and Merlyn are my newest ones, and this is the first time I have had more then two with symptoms. They are only at the trembling leg, slipping, crouching while eating stage but I had to put Dego and DaVinci in a crate so they can relax and get easy access to food and water and Merlyn could n ot get up on a perch with out his mother's help. I let them have a fighting chance, but I doubt they will make it.
Degotoga and DaVinci are believe are biological brothers. They are both white with light skin, a small crest, and feathered feet. They are around the same age, about 45 days or so. Merlyn is dark skinned with a crest, paint spots on the body, and is only 30 days old.

So, what could it be that causes these specific bantams to get the illness and not others? Could it be toxins in the environment? I've raised them in different buildings and they generally have access to forage to balance out their diet. It isn't inbreeding, I do my best to avoid that. They don't seem to have consistent genetics besides that they all have the color white and are all bantams. It always occurs before 50 days of age and after that I don't have to worry. It has never happened before they are feathered.

The breed has Silver and Gold Sebrights, White and blue and black silkies, and Silver Duck-wing and Red Pyle OEGBs in its mix.

Sorry for the long description, but I hope this helps. THank you for any input!