If its not Mareks, what could it be?

[WhiskeyShadow]

After my first 2 deaths this spring, I've had necropsy's done. Each came back with tumor growths and 'most possibly Mareks'. I had PCR tests done for Mareks & ALV. Both came back negative. I know I've had coccidiosis several times this year, I can't seem to shake it. But I've lost as many young <20 week old birds, as I have lost +2 year old birds. What causes the exact same symptoms as Mareks (lameness, loss of balance/function to walk, wasting away of the muscles), but isn't?

Side note: I had a Mille pullet have 2 tumors on her skin (chest, crop area & back of wing at elbow joint) that broke open. As a last ditch effort, I injected her with LA 200. The sores healed up completely with 1 week. This was my first sign that maybe I'm dealing with Mareks. I'm very thankful for the negative PCR, but I'm clueless as to what I am dealing with.

 

[RoostersAreAwesome]

This article lists several diseases that are similar to Marek’s: https://www.backyardchickens.com/articles/the-great-big-giant-mareks-disease-faq.66077/.

 

[WhiskeyShadow]

This article lists several diseases that are similar to Marek’s: https://www.backyardchickens.com/articles/the-great-big-giant-mareks-disease-faq.66077/.

Thank you very much! I've been looking for exactly this for hours now so this is very helpful.

 

[arkansas_ash]

Thank you for doing an unpleasant job and sharing the photos with us. I've lost quite a few chickens to what I believe to be Marek disease in the past and have never had the stomach to do an autopsy. I recently lost a Golden Spangled Appenzeller Spitzhauben rooster to this disease. He first showed symptoms last summer when one of my Easter Egger hens got sick with it. He had a left wing droop for several weeks. He got better and recently he started acting lethargic, difficulty walking, and his tail drooped. He still had an appetite. I finally checked his body over in case he had lice, or anything that would give a clue. Brought him inside and checked him over. He had whitish pasty diarrhea and I spotted Bot fly larvae on a growth near his vent. I ended up putting him down. The Easter Egger hen had slight paralysis in one leg, but she get better, but then maybe two months later lost her eyesight. The 3 1/2 yr old rooster had been vaccinated for Marek's at the Cackle Hatchery as a chick. Thanks for the article - reading that article on Marek's was very informative as it looks like some chickens carry a gene that makes them get Marek's if given a certain type vaccine for it.
Here are some more informative links, as what I have on the disease is photocopied information I got back in the 90's on the diseases of chickens, so a bit dated. They mentioned Marek's, mainly for younger birds, and Range Leukosis for older birds.
Lymphoid Leukosis Merck manual
Marek disease Merck manual