Horse Allergies: Hives, Itchiness, Coughs, Runny Noses and Dermatitis

Buckskin horse swishes his tail at flies
Image Credit:Suzanne Cummings / Getty Images

Every August, we can almost count on a few of our horses breaking out in rashes of tiny hives. We're sure it is an allergic reaction, but with hundreds of plants and trees pollinating at the time, it's difficult to pinpoint exactly what the culprit is. In one specific case, we had an Arabian mare that would break out in silver-dollar-size hives when the Jack Pines pollinated every spring. So if you're wondering whether horses can have allergies, the answer certainly is yes, and pollen isn't the only thing that can cause an allergic reaction on a horse's hide.

Causes of Allergies in Horses

Allergic reactions in horses may also be characterized as hives, urticaria, dermatitis, or hypersensitivity. Many things can cause allergic reactions, and some people feel that, as with like humans, pollution in our air, food, and water are making horses more sensitive to their environment. Common allergens include:

  • Feeds and fodders, including weeds horses, should not, but do, eat
  • Insects
  • Pollen from weeds, gardens, and trees
  • Grooming Sprays
  • Shampoos
  • Fly sprays
  • Synthetics or finishes on equipment
  • Dust and molds
  • Medications or supplements
  • Crop sprays and other chemical treatments that may drift from neighboring fields or are applied to feed crops
  • Stall bedding materials

In short, anything that your horse can ingest, inhale, or come into contact with could potentially cause an allergy. Of course, most horses can cope with most allergens, but some horses, like some people, develop sensitivities for no obvious reason.

Common Symptoms of Allergies in Horses

Many allergic reactions start out with hives. The hair stands slightly, and you can feel the raised bump on the horse's skin. Hives can be tiny or large. Eventually, the hair may fall off of the hives, leaving behind tender patches. There may also be flakes of dander and itching or sensitivity. Many times, hives disappear as mysteriously as they've appeared, while other allergic reactions take longer to clear up. Horses may rub their tails on fence posts or scrub their manes out by scratching their necks on feeders, branches, or trees.

If pollen or another inhaled irritant is causing the problem, your horse may also cough, have a slightly runny nose and eyes (some clear discharge is perfectly normal) or have slightly raspy breathing. Severe allergic reactions might include edema. Contact dermatitis will appear as a sensitive area where a piece of equipment has been on the horse, or where something like a grooming or bug spray has soaked through the hair.

Allergy Treatment for Horses

Allergic reactions tend to come and go quickly, and in some cases, your horse may be over the symptoms before you've figured out what caused them. You may find the horse reacts at the same time each year, or perhaps never again. If the allergies don't clear up quickly and are causing you or your horse a lot of distress, veterinary testing may help determine what is triggering the allergy.

Corticosteroids or antihistamines can be helpful to quell the reaction. Some owners feel they've had success with supplements that boost immunity, such as omega-3 fatty acids, blue-green algae, and traditional Chinese medicine (TCM). Itching and irritation can be treated with soothing topical washes, ointments, or lotions.

Preventing Allergies

The only sure way of preventing an allergic reaction is to separate the horse from the allergen. It may take extensive testing to find out what exactly is causing the allergic reaction. Once the allergen source is determined, you will either have to remove the source or move the horse to another location. Sometimes neither is possible. In the case of our August 'breakout' horses, there are too many horses to relocate and too many plants to figure out what the cause is. Thankfully, it is always a mild reaction—unsightly and slightly itchy—that disappears within about 10 days. For horses with severe allergies, your veterinarian should be able to provide you with medications to combat the symptoms. If the horse is very distressed, however, relocation may be the only solution.