One vet said (over the phone) maybe onchocerciasis, but the one we saw in person yesterday said the presentation was atypical for oncho, and suggested either pigeon fever or "hypersensitivity." Treating with dex and Dermalone (steroid) cream. And Equimax in case it's oncho.
Ultrasound did not reveal abscesses or pus pockets, but oozing serum was cultured and sent off for pigeon fever test. Results in 5-7 days.
Mare practically faints with pleasure when the afflicted area is washed and treated, so it's obviously super-itchy and possibly not completely agonizing.
What is your weather like? Any biting insects around? I'd be inclined to guess an allergic reaction to some kind of bite. I also knew a horse that got (what seemed to be) hives, but the dry itchy lumps turned into serum-y crusty lumps. The vet in that case also diagnosed an allergic reaction of some type. It was rare enough that I don't think the owner sought any more in terms of diagnosis but did treat the reaction topically and (I'm pretty sure) systemically.
Proudly with HRC -- "SJW" isn't an insult where *I* come from.
Did you know that if you say the word "GULLIBLE" really softly, it sounds like "ORANGES"?
Oh heck yeah, we have voracious blood-sucking and stinging insects out the wazoo here in Cottonmouth County. In fact, one of the vet's suggestions was fire ants, although because of the location and nature of the assorted inflammations, this theory seemed pretty far-fetched. Based on the 6 years I didn't spend in vet school, allergic reaction to gnats or whatever seems more plausible to me. The new fly sheet is ordered in any case.
Yeah, temp and respiration all normal. In fact, the whole horse is normal, except for the pus-bags. She's eating, drinking, nickering, and smushing her butt up against things just like she always does.