I noticed several weeks ago that one of my black chickens was looking odd. She seemed to be carrying around a lot more weight around her neck than the others.
My faithful chicken book didn't say much about this, so with a quick internet search I found that she most likely had a "sick crop." The possible causes could be bad feed or foreign objects. I ruled out bad feed since none of the other chickens were sick.
Here's a little education for you non-chicken people.
Chickens don't have teeth but have several digestive areas. They instinctively eat small stones and gravel (grit) to help break down their food. The first area is a pouch called the crop, which is actually part of the esophagus. Chickens eat all day and the food initially goes into the crop where it softens with digestive enzymes. When the system is ready, usually at night, the food is drawn further down the system. Any blockage in the digestive system can cause a backup into the crop. Normally the crop is the size of a golf ball and can be visible later in the day.
So I watched the poor thing as she got more and more bloated, hoping things would improve. Her crop had expanded to the size of a grapefruit or softball and was throwing off her balance and making it difficult to walk. The best advice I had was to just cull her (i.e. kill her and put her out of her misery) but not eat the meat. Unfortunately I wasn't prepared for this step yet and each day looked for improvement. So, it happened one morning she was sitting on the floor of the coop, unable to get up and eat. I tried to help by massaging her neck to relieve the pressure, but I think in the end probably only suffocated her.
These are the harsh realities of farm life. I'm not sure I'm ready for them.
After she eventually died, I needed help to do our own little autopsy to see what the potential blockage might have been. I suspected it was some sort of foreign object like a piece of plastic. The crop was full of grass and seeds. Lots of compacted grass and seeds. We didn't dissect any further. I'm too squeamish.
For those interested in what we did with the carcass...we buried it in the compost bin.