I brought her inside last night with another hen for company, the swelling was a bit worse (spreading towards her eye in the evening, with some draining out her ear) so we wrapped her in a towel and did some hot compresses while we watched a movie and she spent the night inside by the stove for warmth. This morning, the swelling is much lessened and she is eating and drinking ravenously - not just treats, but her regular layer food as well. Her eye is totally clear, though she's still a bit crusty around the ear on that side, which I am taking as a promising sign in conjunction with the reduced swelling - it says to me that the infection is draining on its' own and her immune system is doing what it should. No one else is showing symptoms, in fact I heard not a single sneeze or rasp when I was in the coop for almost 30 mins this morning (still gonna give the final dose of abx tomorrow though, no reason not to). Yesterday they laid more eggs than they have since I moved them to the new house, so I think things are looking up.
As for the permethrin, I am pretty leery of insecticides and things in general - for me, using permethrin at all is a last resort, but as it's derived from chrysanthemum flowers seemed to be the least invasive of the really effective ways to control lice and mites - I've had terrible experiences with Ivermectin and Frontline both, with dogs and dairy goats, and hesitated to use something off-label for my birds (a good friend's dog died horribly after an allergic reaction to topical Frontline at the recommended dosage, it's not nearly as safe as it's made out to be, and ivermectin is just SCARY). Mites have been a HUGE problem this year in my state, though. Only a couple of people I know have escaped major outbreaks, and many have lost prized birds to them this year in my area, so when I saw one I did NOT want to run the risk, especially since my birds free-range and come in contact with/range in the same areas as wild turkeys, crows, and other wild birds. I did three lighter-than-the-bottle-said-to applications, one on the old coop and one in the new coop on the same day (about a week before I moved the birds, and I was sure to treat the old coop when all the birds were out free-ranging at the old house), and another in the new coop two days before I moved the birds in. There is a bit of permethrin dust in their sand box, but it's maybe 2 shakes of the can mixed into over 150lbs of sand, wood ash, cedar chips, and diatomaceous earth (also used sparingly, but not as sparingly as the permethrin). I also washed all the birds in shifts over a couple of days (limited space to dry them by the wood stove, and being off-grid a hairdryer is totally out of the question), using peppermint & rosemary castile soap and a strong vinegar solution. I haven't seen any lice or mites since.
I seriously doubt it's fowl cholera. Only one bird showing only one symptom does not a diagnosis make. All of the flock has (and has had) normal poops, no swollen feet, no one is showing any lameness, and no one is rattling when they breathe. In fact, they're all bright-eyed and bushy-tailed, REALLY mad at me for not letting them sneak out for a free-range in the snow today. I've been monitoring their condition carefully since I first heard sneezing, and no one has lost weight - if anything, all the extra treats they've been getting are making them put on weight! (My sister works in the produce department of an organic grocery co-op, and has been supplying me with fresh produce and expired raw milk yogurt for them while they're on ABX, which they are DEVOURING like the little feathery velociraptors they are). Going immediately to the worst-case scenario when the evidence doesn't fit with it is not helpful to anyone.
I did get both landlords from both houses (old and new) on the phone last night to quiz them about the health of their birds. Neither of them had any respiratory issues at all when they kept chickens, never had a mysteriously dead bird, sudden drop in egg production, or any of the other things that would trip a warning bell in my head, so I am thinking that it's probably just a common cold or allergies combined with stress and dust from being moved, possibly combining also with a reaction to having her beard plucked out by that darn red sexlink. Regardless, I have contacted all the people who were scheduled for picking up hatching eggs over the next couple of weeks and put them off until I have more observation time, but I am not going to cull the whole flock unless it becomes absolutely necessary and I have clinical tests to prove it. Getting a vet tech friend on the phone last night was very helpful - she made the excellent point that the common cold happens in birds too, and is just that - common. "A darn sight more common than MG, IB, or cholera" were her exact words. She also reminded me that the internet is not a veterinarian, that I take generally excellent care with my birds, and that my own experience and instincts with animals are usually spot-on (I've worked with many, many species of animals for many years, from dogs and cats to coatimundis and macaques).
She'll stay inside until the swelling is gone or she dies (which is seeming less likely by the minute, she's determined to get out of her box and explore the living room this morning, which doesn't tend to be the modus operandi of a dying bird), and I'll hold off on selling any more hatching eggs or any chicks until I've hatched out another batch of eggs and have the information from that.
