Some Icelandic Horses can be victims of summer eczema (sweet itch). A higher percent of imported Icelandics develop SE than domestic Icelandic Horses.
From an owner of an SE horse:
We are at the height of the SE season here and at the time of year , when in the past, we have been in bad shape - no tail (rubbed off), scabby face, sores on chest and belly, etc.
I am happy to report that we are in much better shape this year and I really attribute it to being proactive before a problem developed. We do have some itchiness and scratching (the bugs are really bad right now) but nothing like we've had in the past - very much at a manageable level.
I started my Icelandic Horse mare on ground flax seed this winter and switched her to BOSS this spring (just because of the convenience) which I think helped her general skin condition. Then as soon as it got warm enough for bugs I started her on EquiSpot and I put SWAT and Desitin (used on alternating days - Swat 1 day, Desitin the next) on her ventral line. Now that the bugs are really bad I have started putting M-T-G under her front legs at the elbow (the bugs really like that area, too).
I think getting started on this regimen before we started seeing signs of SE made a huge difference - if you wait until you see the signs, it's like you never catch up. Even though she is still a little itchy, I wouldn't call her anymore uncomfortable than most horses this time of year.
I am soooo grateful because it is awful to see them suffer when they are eaten up with the cullicoide reaction. I went back and figured it up and my mare was in the states about 7-8 years before the SE developed.