Chicken not using legs

[Debrohlik]

We have an approximately 12 week old chicken that is not standing. It was noticed about a week ago and she is separated from the flock. She is eating, drinking and pooping normally but has no/little use of her legs. According to the records she was vaccinated for Mareks. No other chicks in the flock are exhibiting any signs.

 

[azygous]

Marek's isn't the only virus that causes lameness. Marek's vaccine won't cover lymphoid leucosis. It produces similar symptoms.

Since there is no treatment for it, I suggest you treat for the paralysis. Lameness can sometimes be caused by a bacteria or a vitamin deficiency or even heat related issues.

Just recently I treated a hen for these symptoms and she has made a full recovery after being so sick I thought she'd need to be euthanized. My treatment consisted of an oral antibiotic for ten days, daily vitamin B-100 complex, St John's wort, a probiotic tablet to counter effect of the antibiotic on crop yeast, and a 81 grain aspirin twice a day for inflammation. She is now back to full health and mobility.

 

[RoyalChick]

I have had a young chick who suddenly stopped walking. One leg was affected. I treated her with vitamin B2 and it resolved. When I stopped the vitamin B2 her other leg stopped working. I put her back on B2 and she recovered.
She is now just over three months old and walking fine with both legs.
I still give the occasional vitamin B2 supplement but I think at this stage it is more for my peace of mind than for her leg.
Vitamin B complex and particularly B2 which is the one most often associated with paralysis is very safe. They just excrete any excess. So it is a no regret to try that. Mine seem to find the taste OK to both food and water and when I sprinkle the contents of a capsule on mash they fight to eat up the pretty orange bits!
You can get capsules for human consumption at the pharmacy. They typically contain 100 mcg of active vitamin B2 in a powder.
You can also give the full Vitamin B complex the same way. Mine were fine with the taste of that too.