- What you see: Raised bumps on the skin
- Panic level: Yellow (caution)
- Causes: Many and varied
- Immediate Action: Cool hosing, clear aloe gel on areas, antihistamines or corticosteroids if severe
- Call your vet: Only if recurrent or if accompanied by severe signs such as breathing or diarrhea problems
- Prevention: Determine the cause of the allergic reaction and remove it from your horse's environment
Hives are a health problem that even unobservant owners tend to notice. The swellings in the skin cause hair to rise and ?lumps? can be seen from a short distance as well as felt. Hives usually appear within 15 or 20 minutes to an exposure to the causative agent but can also show up hours later.
The hives themselves are a mild allergic reaction. Occasionally hives may be painful but? more commonly they're itchy. Usually hives will show up on the back, neck and flank area of a horse. Insect-bite-related hives often appear on the belly. Some horses may get swollen eyelids or swelling of the muzzle and lips as well. Generally hives disappear on their own in a few hours, unless horses are continually exposed to the cause of the allergic reaction.
Insect bites and stings are probably the most common cause of hives. This is often worst in the spring. Next are plants that are irritants, such as stinging nettles. Topical or oral medications, including vaccines, can cause hives. A? new fly spray may also cause an allergic reaction. A few horses will show allergic reactions to some types of forage, including new grass in the spring.
Your first goal is to make your horse comfortable. Cold hosing will often take away any sting and itchiness, and help reduce the swelling. Topical treatments such as aloe and tea tree oil may help if put directly on the swollen areas (only choose tea tree oil if you know your horse isn?t sensitive to it; some horses are). Hives usually clear up almost as fast as they appear.
Your second goal is to determine what is causing this allergic reaction in your horse. Certain times of year are notorious for nasty insect bites. Try to keep your horse in during peak insect feeding times of dusk and dawn. Use basic fly control such as flysheets and masks if your horse reacts to the common fly spray ingredients. If you just used a new saddle pad or blanket or tried a new supplement, that could be the cause of the hives too. You can do a controlled experiment with a small exposure to see if those things caused the reaction.
Food allergies and sensitivities may also cause hives. Think about what new or unusual foods your horse might have been exposed to. You can do ?testing? again by an exposure to a small amount of the new items to see which ones, if any, are causing the problem.
You then need to avoid those foods if possible. Food allergies aren?t common in horses though.
Some horses, with Arabians and Thoroughbreds leading the way, are also allergic to inhaled pollens and molds. This is called atopy. Management can help with many cases of atopy. Keeping your horse indoors during high pollen times and seasons may help to manage this problem. On the other hand, for horses with dust sensitivities, keeping your horse outside may be the ideal solution.
Atopy may require veterinary intervention with the use of steroids if it is a short-term exposure or developing a program with allergy skin testing and desensitization injections if need be.
Article by Contributing Veterinary Editor Deb Eldredge DVM.