So, this summer, my horses had hives. Again. My 20 year old Haflinger mare has insect bite sensitivity and probably allergies to unknown pollens since she reacts often in summer and early fall. She gets hives and is on Hydroxyzine and some skin spray during reactive times. My 18-year-old TWH mare has had hives a few times also. But this year, it’s been hot and wet, muggy and buggy. Both came down with hives AT THE SAME TIME. It’s awful to see your pretty sleek horses covered in welts and bumps. Of course, this ALWAYS happens on a weekend or after hours and I have to bother my vet. Thankfully I have a lovely vet, who answers my texts, looks at photos, and is a calming influence.
Besides trying to do SOMETHING to treat them, I had to try and figure out what caused it and stop doing it. First, they both had Hydroxyzine right away. Teagan the Haflinger had already been on it prophylactically and Gypsy the TWH mare is now on it.
What could have happened the previous 24 hours to cause this? And yes, sometimes, what causes the hives is something that happened 24 hours or more ago.
1. Both horses were dewormed for the first time in months. (We usually do fecals.)
2. They were in the grass paddock, which was buggy and humid. There may be new weeds, new pollens?
3. They were fly sprayed up close and personal instead of the usual misting.
4. All the recent rains in our area produced a new crop of mosquitoes.
Meanwhile, I turned to “google” and my “horse groups” on social media. Research horse hives and there is a wealth of information. What did I learn?
•It is very common. Some photos show horses much more hivey than my two.
•It can be extreme. It can go away as quickly as it comes and it can linger for days.
•Some hives are caused by allergens for which horses can be tested.
•Sometimes the hives itch, sometimes they don’t bother them at all.
•Some hives are small mosquito bump sized lumps all over. Sometimes the hives are localized. Sometimes they are spread out and large swellings.
•One usually never can tell what caused the hives, especially if they disappear in a 24-48 hours.
After consultation with my vet, we decided they may be bug bite reactions. The mosquitos were bad, and hatched a fresh crop after recent rains. My horses get sprayed with insect repellent every day in bad buggy weather and every other day as needed. I alternate sprays so effectiveness stays high. As I said, usually I mist and this time I doused them because they were on the grass pen, where they were lots of bugs.
It probably was not deworming, although horse people know sometimes pinworms come out as hives or some other gross horse thing. My vet didn’t think it was caused by that since the reaction was not immediate.
Was there something in the hay? It is a rough hay season in the Midwest because of the rain, so maybe there was a weed.
Now, sometimes hives can be very serious. If it’s a serious allergic reaction, and your horse has trouble breathing, don’t waste time googling crap! Call the vet immediately! If your horse is in severe distress, itching, scratching etc. call the vet. In fact, when in doubt, call the vet. That’s pretty much my mantra. Yes, I was the same way with my human kids, and AM the same way with my KanineKids.
Because of the bugs and weather, I decided to keep them in their freshly cleaned stalls loaded with fresh pine shavings at night. Usually they have access to a small paddock and can go in and out of their run in shed stalls at will. I dosed them with their hydroxyzine and sprayed their hives and welts with the EquiShield IBH Spray. The next morning both were better although my Haflinger mare still had a large swelling which could have been a bee sting or a bug bite reaction.
I was lucky. Or should I say my horses were lucky. Actually, we were all lucky. Within 2 days, their hives were gone. I stopped using the green bottle of fly repellent and rotated between two others in the supply. No, I still don’t know what caused the hives for sure, but this time I’ll go with bug bite sensitivity.
For more information, GOOGLE it. There is a lot to wade through. Also, I found a great article that I recommend in Horse and Rider Magazine. https://horseandrider.com/horse-health-care/horse-hives