The Neverending Hives; myself, trainer, & vet all out of ideas
So I love my pony dearly, and I take excellent care of her. I often get laughed at for "bubble wrapping" her because she is so special. And now (well since September), out of the blue, she has had hives!
It wasn't that bad at first, little patches of small bumps here and there that would go away in a day or so and then it started to get worse and worse. I clipped her around the middle of October when she didn't have an outbreak, head, legs, and all. I was hoping that would cut down on her episodes but by December about 50-60% of her body was covered in hives. Again, small bumps, down her neck, over the majority of her barrel, not on her back, on her flanks and the sides of her butt, and down her legs. I clipped her again on the 23 when it was the worst and gave her some Dex and that seemed to calm everything down for a few days.
Around the 28th the hives arrived again on her neck and shoulders mainly on the left side and I got my bottle of Dex and she's been on that in varying doses between 5cc and 1/2cc ever since.
Since the onset she has gone from not wearing blankets to wearing blankets to not again (NC is having an unusually warm winter) and there has been no direct correlation between heat or sweat and the hives. I've tried working her and not working her. She's gone from being on Strategy, to just plain oats and canola oil. She is on a dirt lot with controlled access (Hotwire gate) to grass, so she's not getting into weeds because she doesn't go out on her grass all the time. The trees all have fence around them so the horses can't chew on them, so she's not eating tree bark. The fencing is not treated with creosote. The other horse in her pasture has only had hives once in all this time and it did not coincide with my pony's episode. We've tried watering the hay. Their water tub is dumped and scrubbed at least once a week. We've put a cribbing collar on her so she can't chew on the fence wood (yay for her being short). We get a new load of hay every 2-3 weeks and the only horse on the farm that has a problem with it has a dust cough, which is fixed by watering the hay. She's not getting in to another horse's feed, everyone is being careful about that. She gets fed twice a day and hay 3 times a day on top of that so its not like she's ever going long periods without food in which she feels the need to eat other things.
She's been treated with lymdyp "just incase" and it had no effect except to stink up her blankets. 2cc of Dex doesn't necessarily work on a reaction anymore, and she's starting to get cranky and sluggish so I'm weaning her off the Dex at the moment. I've used the Cortaid spray with success but it took almost the entire bottle and the hives came back again within a day or two. We've tried keeping her turned out on her grass during the day versus in her dirt lot but it doesn't make any difference. We haven't been able to do any allergy testing because she's been on the Dex but I think with such a strong reaction I'm hoping the blood test will be sufficient (for my wallet's sake).
I do want to say that my pony will eat (and has tried to) eat anything she can get her mouth on. There are dead leaves in her pasture from sweet gum trees and oak trees but it's already been ruled out because the dead leaves she occasionally nibbles on are black/brown and rotting on the ground. She could eat her whole paddock clean without any problems.
She has been on and off itchy and/or sensitive where her hives are and has rubbed out her hair in patches. Her hives are getting worse again though. I looked at them today and they are all over her belly and they're more like welts and it kind of looks like welts on welts, as well as her usual bumps on her shoulders.