Treatment for hives on horses?

my horse has hives and ive heard that apple cider vinegar will get rid of them is this true?

Every time a horse breaks out in hives your vet should always be called, and no treatment should be instituted until the vet prescribes it. There are multiple possible causes for hives to develop, and some are very serious while others are more minor. But treatment varies depending on the cause, and your vet should really be the one to determine what treatment is best in your horse’s case. It is safe to rinse your horse with water if you think the cause is something topical that you applied or that he rolled in. But beyond rinsing him off, I’d wait for the vet to advise you.

Add….antihistamines like Benadryl are contraindicated in some condtions causing hives,so you shouldn’t give them unless your vet prescribes it.
Also, giving any medication before your vet sees the horse can alter symptoms and confuse diagnosis.