Cellulitic reaction to fly bites?

[pastel]

I have managed a retirement home for horses since 1989,we have 48 horses and i have never had any allergic reactions to fly bites before like this, this year we have had several horses in different fields come up in hives/large fly bites with some oedema in places especially on belly, this was before the horse fly season , we do have fly traps and put fly rugs on when its the horse fly time, last week 2 mares in the same field had swellings around fly bites then their muzzles swelled up a bit with oozing yellow clear fluid, that went down but now it seems the same has happened on both horses heels , its extraordinary, i haven't given them any steroids as both laminitis prone and they seem past the peak of the reaction as swelling gone down, they both had bute , obviously if symptoms got worse i would have called the vet but we managed it by hibbiscrub and bute , has anyone else had similar symptoms ?

 

[BBP]

About 4 years ago BBP went through this in the summer, huge welts oozing serum. With him it turned out to be biting ants (only fully knew when I found one attached to him). He would paw at and mess with the ants nests and so had them on his face, legs, body, everywhere. I think I used antihistamines anyway for his hay fever. Then antihistamine cream on the bites. Not sure it helped all that much. I now fence off whatever ants nests I find if I can. Haven’t had it reoccur any year since. Was very weird. The other horses didn’t get them but none of them would roll and mess about near the nests like he did. People say most ants don’t bite but these definitely did.