Hi, I've been trying to find photos/videos for examples of what Marek's could look like. I did do a post about my then 9 week chick who's been gradually getting worse since 1-3 wks old. I guess my description wasn't helpful. Thought maybe you might be able to help based on your responses to this thread. My hen is almost 11 wks now. It started with open mouth breathing (no noises) mostly at rest. Then for a week or 2 she had a right eye that she didn't fully open.
Rather than Marek's, this sounds to me like a respiratory disease, possibly Infectious Bronchitis. You haven't said whether or not she was given an antibiotic or if any other birds showed symptoms like hers. If she or any others you have are still showing or starting to show symptoms like this you can put them on Duramycin-10 1/2 tbls. per gallon, for 7-10 days.
Then I noticed she stays pretty ruffled and her crop was huge and off to the R but when she doesn't eat, it appears to empty. She continues to stay ruffled and seem heavier than the other orprington. Then I noticed she keeps her head in close to her body and appears to be right side heavy. Her R wing has been drooping more and more and she loses balance easily, primarily backward. I had to build a ramp for her to use the roost. Each week, she seems to stand around or lay down more and more.
What do her poops look like? It sounds almost like a coccidiosis or worm problem. What about mites? Check around her vent and see if there is any bare, red skin. What is she getting for feed? Treats? What are you using for vitamins?
I thought to take a picture of her skin/feather follicles but she's giving me a hard time. Here's what I've got. Any thoughts would be great. Oh, I've been giving her vit/min in her water since the breathing problem which has since resolved (I think). I don't think the eye thing is the same as the person's chick who started this thread but who knows?
I am going to post some links for you for Marek's. That said, I think the other issues need to be taken care of first, as I'm not sure it is Marek's. The backwards falling and drooping wing can be caused by a vitamin deficiency. You might want to get some human vitamin E capsules, I use the 400iu and squirt one onto her feed as well as continue with the vitamins in their water.
This may if fact be the first signs of Marek's but again, need more info about her and any other birds you have. If it is Marek's, there's not much you can really do, so let's take the time and look at everything, so nothing is missed. Chicken diseases all seem to start off with the same symptoms, it's the subtleties, that are sometimes hard to see when we are new to chickens, or never seen the symptoms before, that tell us what we are dealing with.