My 13 y/o QH/TB cross got hives out of nowhere December of 2010 for the first time. He had never had them before and nothing in his life had changed. It took Dexamethasone to get rid of them. My vet said horses don’t have the same receptors to respond to antihistamines (like benadryl) like humans do, and they don’t work so don’t even bother. The dex worked great.
He’s gotten them ever since that first episode. I have ruled out EVERYTHING! He’s been at different barns, different hay, different bedding, no bedding, no blankets, taken him off grain and supplements, tried supplements like omega horse shine. I can’t for the life of me find a trigger. He gets them all times of the year for no apparent reason.
I always give 8mg dex oral tablets once a day until they’re gone, which is a pretty low does. It works in about 48 hours. Sometimes they’ll be gone for months, sometimes they’ll be back in a few days.
Last week I tried not giving him the Dex to ‘ride them out’ and his face is so swollen now that he can’t hardly open his eyes and the hives are oozing fluid and have actually broken open into sores. So now he’s on dex and antibiotics.
I’m at my wits end and don’t know what to do. Someone yesterday mentioned trying weed free hay, so I might give that a go. I’m considering trying a grain free diet, again. If it weren’t so cold now I would give him an antimicrobial bath, I don’t think they made a difference but at least I feel like I’m doing something.
I know this doesn’t help you, but you’re not alone.