The history of this:
He went down fast. During the hottest week of summer, still not really that hot, his crow sounded a bit weaker. Thought he was just having a bit of heat stress and he'd get his big howling crow back. He never did.
Then, he was sleeping more and more, going to roost before his hens, nodding off at the drop of a hat. His color would go dark, then recover. He was in molt, so at first, his small weight loss wasn't unusual, but a couple of weeks ago, it was much worse and now, he has very little meat on his keel. His color stayed dark and the comb was withering, points curling over, so I figured his big old heart was slowly failing. Still, he was crowing every day, albeit sounding pitifully weak, no lung power.
He had runny, green poop that we had to wash off and found flies starting to lay eggs in it, what with him laying around so much of the time, but fixed that pronto. We brought him in the house, then noticed his abdomen felt wrong, too tight. And since he was in a dog kennel, we also saw he wasn't pooping solids at all for a few days. Tried to remedy that, and he did manage to get out some semi-solid poop, but not nearly enough for what he'd eaten over the past week.
Now, I think he may be in renal failure, but contrary to what some folks on BYC think, I'm not a vet and don't know everything. It's just a guess, judging from what happened with a dog I had and his symptoms when his own kidneys failed the day he died.
All this has happened in stages over the space of about six weeks. Before that, there was not a sign that he was anything but a big healthy rooster, old yes, but very healthy and robust. One of his hens is dying right now of Egg Yolk Peritonitis and they will be buried in the same grave. It's touch and go as to which one will go first, unless we just take matters into our own hands with one or both. Her, it isn't as difficult. Suede is another matter.