Hives? Allergy to flies/summer?

[sjdress]

My very sensitive horse has come up in what I presume is hives but could be allergies to fly bites as he get quite sore on his face from them. The ‘hives’ are all down one side. Any advice for this? He is in during the day and out at night but seems to be coming out in them in the day rather than when he is out. They appear to be itchy but not particularly sore for him.

 

[Shay]

Could there be an ant nest in the stable? The red ones bite.

 

[Fransurrey]

Is he bedded on straw?

 

[Green Bean]

My mare also broke out in bumps down both sides last week. Thought it might be her fly stuff, but it appears there are different biting insects out there this year because of the wonky weather. She is over it now so presume it was one hatching of the new bugs.