Hen dropped dead....

[KirstKennedy]

I have no idea what happened. She was fine and then an hour later I find her like this! No signs of anything wrong with the others. Can't see anything wrong with Carol the deceased hen and she was only 1 year old. I'm going to give the coop and run a good cleaning and put ACV in their water. Also might sprinkle some DE around. No signs of mites/lice or worms. She laid an egg yesterday. Was this likely just a one off thing? I've never had anything like this happen. The only hens I've lost are 2 to a coyote when free ranging a couple summers ago. Anything else I should do to prevent any possible cause killing my other hens?

 

[coach723]

If you still have the body I would recommend a necropsy, otherwise we'd just be guessing. They can die suddenly from all sorts of things. There may have been signs you missed, she may have had a heart attack, fatty liver hemorrhagic disease can cause sudden death. It's just very hard to know unless you look.
Here are some resources for getting a necropsy done, you can also do an informal one yourself look look for obvious things, if you are up to that. Others here are willing to look at pictures to give you opinions based on their experience.
https://www.aphis.usda.gov/animal_health/nahln/downloads/all_nahln_lab_list.pdf
https://www.metzerfarms.com/PoultryLabs.cfm