Hello everyone! I recently (as in a week ago) purchased a 5 year old TB gelding with the typical “thin hair”/sensitive to bug bites type. Everything was going great until I realized that every time after I ride him and he gets sweaty, he developes hives. These are mostly localized up his buttocks with very few on his neck/sides, and develop more-so on his right side than his left. After hosing him off and turning him out, they disappear within the hour every time. I brought him in from the pasture today and he had a few in the same areas as he had sweated a lot due to it being in the 90s today. He never displays any sort of discomfort and I’m pretty sure he doesn’t even know they’re there. He is on good pasture with grain morning and night with beet pulp/small amount of molasses in between when he comes in for the hottest part of the day. I don’t see this as an allergy to something due to the fact that the hives only appear when he gets sweaty. Is there anything I can do for him? I plan to make him up into a nice show horse, and while not extremely noticeable to someone not looking for it, I can see getting hives every time he is worked as something much less than desirable. Anyone that has any suggestions would greatly appreciated! Thank you!
Bump.
Have you heard about soy allergies or sensitivities? It can cause hives.
Hoping you’ll get more ideas/thoughts today.
A couple of things you can try …
The Grapefruit Coat Refresh product - I swear by it. Totally eliminated the hives on my young colt in 2-3 days and he had hundreds of them …
Putting tsp of baking soda in his breakfast and dinner
Dr Reckeweg R17 - 15 drops three times a day in 2-3 ml of water in a syringe shot down his throat. Its for rashes, tumors, growths and it works. Very very well but the main ingredient in it is cobra venom and some people are hesitant to use it for that reason …
So - you have a topical suggestion and 2 systemic ones to consider
Good luck! 
When I was younger, I rode a horse who was allergic to his own sweat (per the owner) and would thin/lose all of his hair in sweaty areas. The hair loss areas got smeared with evening primrose oil and it seemed to help.
Some more things to try:
-Feed flax seed (1/2 cup-1 cup per day, whole or ground)
-MSM (helps with allergies sometimes)
-After you hose him off, add a few glugs of vinegar to a bucket of water. Sponge him with the vinegar solution and leave it on. For whatever reason, it helps with hives.
Also, do you fly spray him after you rinse? You may want to wait until he is dry. Some horses are more sensitive to fly spray when they are wet-- I’m not sure if pores are more open or if the water acts as a carrier and allows the chemicals to reach the sink.
Gotta love those thin-skinned TBs…
My one gelding used to break out in hives on a regular basis. When my trainer moved barns about 4 years ago, they stopped. It was evident that the hives were environmental…he was obviously allergic to something at the old barn. Unfortunately, it’s difficult to know exactly what he was allergic to.
I wouldn’t put too much worry in the fact that the hives occur after he sweats. The environmental factor could be present where you ride, or the sweat is enough of an irritant, (especially in hot weather), that it is compounding the problem.
While we were attempting to treat my gelding, the vet did mention that hives are somewhat common in young horses and much like human children, they can outgrow an allergy. Your horse is young. If the hives aren’t bothering him, I’d just wait it out and see if they disappear as he gets constant exposure to the irritant and develops some immunity.
I had a mare that would break out in hives from oil based fly spray, alfalfa, and neoprene products (leg boots, girths, saddle pads). I could only use water based fly spray on her.
