Marek's symptoms or birth defect?

[Canidae]

So I have 5 new ~4 month old pullets and the cream legbar is showing concerning symptoms. My chicks were all vaccinated for Marek's at hatch, and this chick has always been sickly. From day 1 she had labored breathing and was slower than the rest. I assumed she had some sort of respiratory illness and provided supportive care but thought I would probably lose her. She actually pulled through. However, one of her pupils is slightly misshapen, has poor balance and she's back to acting lethargic since being moved outdoors (heat stress?) I was sure to practice good biosecurity when they were young, and none of my other chick/ens have shown any signs. It seems like Marek's right?

 

[Debbie292d]

Have you had Marek's in your flock before?

I wouldn't jump too soon to thinking it's Marek's, as since you mentioned heat stress, it could be suffering from something to do with that. You said this one started out slower than the rest. It could have just been a potential FTT (failure to thrive) that with your help pulled through.

However, in case it is, here's an informative thread about ocular Marek's.

 

[Rose Quartz]

If they're vaccinated then she shouldn't be showing symptoms if she does have mareks.

More likely if she's been sickly from hatch she has some kind of birth defect.

 

[Canidae]

I haven't had Marek's in my flock to my knowledge- none have shown any symptoms that would make me think so. I started my flock with vaccinated birds so I suppose they could still be carriers. She could also definitely be a failure to thrive. Since they are vaccinated a test would appear as a positive regardless correct?