Firefoot
Songster
It was a broody hen hatch. They were separated with the hatching, and the mother has never been part of the big flock. She's a pretty paint silkie, so I've wanted to give her special treatment, and I don't think that throwing her in with all the other brutes would help keep her clean. The eggs were some of my own that I pulled over from the main flock when she went broody. All parents are completely healthy and over a year old. I give them a diet of layer feed and an occasional treat of seed or cracked corn. Sometimes we give them fruit or bread, but not that often.
About a week before the first chicken died, it was in the 80s weather-wise. Then it dropped down to the 40s during the day and lower in the night. The reason I thought of dehydration was because, in my reasoning, when it's very hot outside it makes the chickens thirsty, so they don't need to remind themselves to drink, but when it suddenly drops down cold, it doesn't make them as thirsty and they don't see a reason to drink as much.
I don't know what the other stuff was. It was a type of pesticide or something that was designed to rid parasites, such as lice and mites, from your flock. I've used it on my chickens and sprayed it inside the coup. It is also good for keeping out nasty flies. I don't have the original container that it was in, so I don't remember what it was called. I got it about a year ago.
That does seem like a pretty sudden temperature difference. I know with horses I'd be watching for colic left and right. And yes, I do think the cold doesn't make them as thirsty, so dehydration could be a factor.
I would try to get a fecal float done just to rule out worms. And if you're sure you don't have mites, and if you don't see any other symptoms that indicate a more serious illness, then a good vitamin/electrolyte for a few days would help. Does their feed have a probiotic? Probiotics, whether in their feed or yogurt, etc., might also help. I think in your other post said it's down near 0 degrees now? So if you're suspecting they're not acclimated to the weather yet, and assuming they are in a dry, draft-free coop, I used hot water bottles last winter on my coldest nights. Obviously it doesn't last all night but it helped a lot. My birds were in a little pre-fab coop with the "roosting bars" like 4 inches from the floor. So I filled glass jars with very warm water and put them along the bars and they would huddle up with them. It worked well and was very safe. On a couple particularly bad nights I baked a giant brick in my fireplace, wrapped 3 sides of it in foil, and put it along the wall facing the birds with little foil shields to direct heat.