Lame young rooster, can't walk despite no obvious illness

[noisegeyser]

A friend of mine has this sweet rooster who's about a year and a half old, and he can't walk. When we noticed him in December he couldn't even hold his head up, but after giving him vitamins (we thought he was B2 deficient) he improved a lot and not only could hold up his head but also walk again. A few months later however, he started to decline more and now he can't walk fully upright anymore. He still sort of waddles around in this sitting position though and has no trouble holding his head up. He has a brother who also has an issue with his legs, but it's not nearly as bad as he only walks with a bad limp despite no injury. To me it looks like this might be some kind of genetic issue they have, being siblings? I highly doubt it's Marek's or anything like that, since he's lived for so long and they've both been housed with many other chickens that haven't gotten sick.

Just wondering what you guys thought, since I was planning on taking him home with me some time in the future and I don't want my chickens to become ill.

 

[Eggcessive]

Does his eye look a bit funny in the picture? How is the other eye? I am not an expert on Mareks, but I do think that still could be possible, and I would get a PCR blood test from here:
http://www.vetdna.com/application/forms/aviansubmittalform.pdf
You can contact them for details. The other way to know is to get a necropsy through your state vet if you lose him. Is he still getting vitamins? Human super B complex tablets, 1/2 tablet daily crushed and added to food or a little water can be good.

How does his crop feel? It looks very full in the picture, but it might just look that way. I hope that it isn’t something like Mareks that might affect more of the flock. You might want to make him a chicken sling to get him up and suspended in front of his food andwater. Here is a link to those:
https://www.backyardchickens.com/threads/versions-of-chick-chairs-please.1166308/
Here is a list of most state vets for a necropsy:
https://www.metzerfarms.com/PoultryLabs.cfm

 

[noisegeyser]

Does his eye look a bit funny in the picture? How is the other eye? I am not an expert on Mareks, but I do think that still could be possible, and I would get a PCR blood test from here:
http://www.vetdna.com/application/forms/aviansubmittalform.pdf
You can contact them for details. The other way to know is to get a necropsy through your state vet if you lose him. Is he still getting vitamins? Human super B complex tablets, 1/2 tablet daily crushed and added to food or a little water can be good.

How does his crop feel? It looks very full in the picture, but it might just look that way. I hope that it isn’t something like Mareks that might affect more of the flock. You might want to make him a chicken sling to get him up and suspended in front of his food andwater. Here is a link to those:
https://www.backyardchickens.com/threads/versions-of-chick-chairs-please.1166308/
Here is a list of most state vets for a necropsy:
https://www.metzerfarms.com/PoultryLabs.cfm

I didn't take the best picture, the grey you see is just his nictitating membrane. His eyes look normal, and no crop impaction issues. I'm still giving him liquid vitamin B2 in his water. If a vet can diagnose Marek's with certainty, I'd love to take him in before taking him home with me. He still seems relatively happy despite his problem, I would hate to see him put down.