Chicken sick and died GRAPHIC pictures of autopsy done have questions

[potagergirl]

We have owned chickens 2 years now and this winter have come into a problem where a chicken will look to have a resp. disease. They slow down/lethargy, hunch their bodies and the color around the eyes changes. There is no swelling, no mucus, no drainage from nose, no rattle to lungs. They eat and drink for the first few days like nothing is wrong and suddenly decide to stop eating. That's when I start feeding them.
I hate using meds but have used a couple trying to figure out what might be the problem. Looking info up I thought maybe gape worm. Not gape worm though.
So we decided to learn what might have caused the problem by doing an autopsy. Not that I know much about the insides of a chicken other than what I have seen from others posting.
Anyway, here are a few pictures from the autopsy. The things I noticed posted with each picture.


Bottom of bird around the breast bone very red before cutting. Checked for signs of skin opens but found none.


Bird is aprox. 12 weeks old has a lot of fat inside. from other pics I've seen this is about normal.


Spleen- black. I do not recall anything about a spleen being black. Is this normal? I'm thinking it is not and perhaps a sign of
infection?


Another view of the spleen which looks to be enlarged?

Sorry for all the graphic pictures but I am at a huge loss as to what happened to my boy. He was young and healthy one day and the next began to hunch like one of our hens did a few weeks ago. We did not autopsy her but now I wish we had.

We cut into every organ and the intestines looking for lesions, worms, any kind of sign or indication of what might have caused the problem.
I would be happy if anyone could help with suggestions of where I can look for answers because so far I haven't been able to find any. I am hoping this is the last bird that dies from this but I'm worried it isn't going to be.
thank you for looking and again sorry for the graphic pictures.

 

[Eggcessive]

I don' t have much experience with necropsies, but I think the black organ is the gall bladder. You can Google "chicken necropsies" and get a few links on what to look for, but several people here on BYC are very good at helping. When you described the issue of the eye color changing and they stop eating, I was reminded of some symptoms of Mareks disease. A necropsy done by your state vet could test for Mareks if you have another death. Sorry for yiur loss.

 

[potagergirl]

Thank you for your insight. Yes you are right it is the gallbladder. I don't know why I kept calling it the spleen.
I've been looking on the net for further information about Mareks and really hoping this isn't the problem not real
happy with the thought of losing my flock but if it has to be it has to be. I'm not willing to keep something like that
on my property that could be transported to someone elses flock.
The amount of time is the one thing puzzling me. Some articles I read say the Mareks will be gone in 5 months
while others say it could take years for the property to be Mareks free. I have a lot more research to do on this
situation.