Sad news, y'all. I lost one of my hens - a black sexlink named Maizy - last night at around 9:30pm. She had been a bit lethargic leading up to her passing, and I isolated her from the main flock a few days ago when I first noticed it. She let me pick her up easily, which she had never really done previously, and felt as though she had lost some significant weight. I don't think she was being kept away from the feeding/watering stations - there's two separate areas - because she wasn't the lowest ranking hen, and the ones who were lower ranking with her are doing fine. When I offered her food and water, she was happy to eat and drink, and her crop was always full. At one point, I was worried she may have had an impaction or sour crop, but she never quit eating and I never noticed any smell. I didn't see any signs of a mouth sore either. Fast forward to today - I decided to open her up to see if there was anything real obvious that stood out to me. I have lots of experience prepping chickens from my time volunteering at a large carnivore rescue. What I saw was her breast was very thin and had a bulbous appearance as though there were numerous, varying sized tumors across it. The swellings were firm to the touch, and when I cut into them, they were not puss filled. I didn't really see any swellings on her internal organs; her liver in particular looked fabulous. Heart seemed a bit small and weak. Nothing really stands out other than the firm swellings in her breast meat. Nothing unusual in her crop or gizzard to suggest an obstruction. I'll be doing some reading today, but I wanted to check in with y'all and see what your thoughts were. No one else in my flock is acting unusual or puny, so could this be a one time thing? I'm really worried about Marek's at the moment and what this could mean for the rest of my flock. Thank you so much for your time and information!