Cornell University has a 4 hour video series on necropsies! This is invaluable! http://partnersah.vet.cornell.edu/veterinarians/avian-necropsy-examination And this person has some very valid points about doing your own necropsies: http://hencam.com/henblog/2013/08/chicken-necropsies/ She is how I found this, by her linking to it. She says: And that statement is the reason I hesitate to put some photos up on this forum. Though many here do know what they're looking at, they tend to elicit some wild guesses from the same people who throw stuff out of left field on sex and breed. I'd rather know something before I post it so that I can educate rather than add to a ton of misinformation posted. Chicken disease is much more complex than most folks understand. For example, they see a tumor, they yell, "Marek's!" A chicken limps, they immediately go to the same conclusion. My Isaac walks like a Nazi and they ask if he has Marek's. Good grief. The guy has walked like that since he was a young adult and some of his sons have that same walk. He also has old age arthritis. Chickens get arthritis. So, it's not always as simple or obvious as some would think.