My horse has "hives" again?

Okay so just about one year ago I posted about my horse breaking out in hives. Small bumps covering his body in patches. Just this evening I went out to the pasture and he has these terrible, ugly nickel to quarter sized bumps on his chest. Only his chest this time. What is it? I can't say if it is the same thing as last year. It's definitely in a different place, and bigger!
Last year they went away after a couple of weeks. I stopped feeding the mixed hay and watched his diet. Then gradually went back to everything as usual. I bought a histamine but never used it. I sprayed him down with anti fungal spray. I can't be certain what worked or what caused it. Nothing has changed but the weather. His paddock has no Oak Trees in it. There are some on the property. It's awful. This year I am posting pics.
http://s1020.photobucket.com/albums/af328/Deniseclaiche/?action=view¤t=DSCN2333.jpg
http://s1020.photobucket.com/albums/af328/Deniseclaiche/?action=view¤t=DSCN2331.jpg

Mom20302011-06-28T12:35:59Z

Favorite Answer

My parents' have a horse that does this every summer too. We think it is a reaction to bug bites. Try fly spray along with an allergy shot from your vet. It works well for our mare.