One of my girls was slowly trailing behind the rest of the flock, which isn't like her. She is the bossy one in the group and usually the leader. Otherwise, she is acting normal...pecking, etc. So, I picked her up to see what was going on and I felt her enlarged crop, which was mushy like a water balloon. Yippee...my first experience with sour crop. We brought her inside (and of course, spent much time reading BYC posts on sour crop!), massaged her crop (which she LOVES!) and gave her apple cider vinegar in water (in a ceramic bowl...NOT metal). She actually pushes against our hand when we massage her crop. After a while it went down and I could feel bird seed (around the yard) that she had pecking at around the yard (not hard though...more like a tiny bean bag). She seemed better. After a while, I picked her up again and it was mushy again. So I massaged it some more (downward as the posts mentioned), but this time there was gurgling sounds and she would open her mouth (like a silent burp).......sour smell. I massaged it down and put her in the large dog kennel (the indoor "chicken recuperation coop", which has an old sheet for bedding, so nothing to eat...just her ACV water). I am assuming we caught it early enough. Is there anything we can do? Most posts say 1 tsp ACV per gallon of water for maintenance...a few said "more" for sour crop. How much more? I think her water is 1 tablespoon ACV to 1 gallon. I also put a couple squirts of Poly-Vi-Sol (WITHOUT iron). What causes Sour Crop? How can I prevent this from happening again? I read that ACV helps keep algae out of the water too, is this true?