With living animals, anything is possible. Some people on this forum, not just on this thread, have seen chickens choke and I believe it happens. I regularly butcher my chickens and have on different occasions found a plum pit in a chicken’s gizzard. That plum pit made its way through their crop and some internal plumbing all the way to their gizzard without them choking. I still believe it is possible a chicken could choke on something much smaller than a plum pit.
I’ve found dead hens before with absolutely no sign of what killed them. With one, it could have been that she flew into something getting down from the roost and broke her neck. Maybe others had a stroke or heart attack. I once had a hen die while laying an egg in over 110 degree weather but she had been acting sick. It’s possible your high heat caused enough stress that it triggered something else if she was sick or had a birth defect. Obviously I don’t know what killed yours.
If it only happens once I’d put it down to when you deal with living animals you sometimes have to deal with dead animals. That’s as true for pet dogs or cats as it is for chickens.
I suggest you call you county extension office and find out about getting a necropsy. That’s an autopsy for dead chickens. Find out the cost (if any), how to handle the corpse, and where to take it. That usually involves refrigeration, not freezing, and they don’t want you to wait too long so it is still fresh. In some states that’s free or minimal cost, in some it’s more expensive. If it happens again you can decide if you want someone to look inside that chicken and determine what caused it.
That’s rough, I’m sorry it happened to you. It doesn’t mean you did anything wrong.
