When your horse greets you with large areas of their body suddenly covered in clusters of bumps, you might wonder if they are experiencing a medical emergency. Urticaria, or hives, are flat, raised areas of skin that tend to form localized clusters. They can vary in size and appearance, and they may or may not itch. Hives are not uncommon in horses and are generally not a cause for alarm. Here is how you can figure out what your horse’s skin is trying to tell you.
Why Do Horses Get Hives?
Hives occur when your horse’s immune system falsely detects a threat, whether it is a food, plant, or other substance. The body produces histamine, a chemical that signals the body to try to get rid of the allergen. Capillaries dilate and leak fluid, creating bumps close to the surface of the skin. In mild cases, hives appear within minutes of exposure and vanish just as quickly.
Some cases of hives are sudden and seemingly random, never appearing again. You may never figure out what triggered them. In other cases, though, they may reappear due to repeated exposure to an allergen present in your horse’s diet or environment. Repeated exposures tend to lead to increasingly severe allergic reactions, sometimes resulting in anaphylactic shock. If your horse has recurring episodes, you will need to work with your veterinarian to determine the cause.
Supporting your horse’s overall skin and immune health with products like those found in the grooming category may help reduce irritation and improve coat condition.
Identifying Allergens That Cause Hives
If your horse develops hives on a trail ride or immediately after spending time at pasture, the cause might be a plant they have come into contact with. It is also possible for insect bites to trigger this reaction. The hives are not bug bites, but rather a reaction to a substance in an insect’s saliva. Using products from the flea and tick category can help reduce exposure to biting insects.
Take note of any recent changes you have made to your horse’s diet, or any new supplements or medications. Antibiotics can cause hives, as can vaccines. Contact your veterinarian if your horse may be having a reaction to medication or a vaccine.
Fly sprays, soaps, and shampoos can also cause hives, as well as detergents used to wash equipment. You might not see a reaction the first time you use them, as allergic responses may appear after multiple exposures.
New bedding or tack made from unfamiliar materials can also trigger hives. In many cases, horses can become accustomed to new materials over time.
If you suspect the cause is dietary, remove supplements, grains, and additives one at a time, allowing a few weeks between each change. Because horses have a delicate digestive system, sudden diet changes can lead to colic.
Not all hives are caused by allergens. They can also be triggered by stress, heat, exercise, or pressure from tack or over-grooming.
What To Do If Your Horse Has Hives
Hives may go away without treatment and never return, even if you never determine the cause. If they persist, and you are having trouble identifying the trigger, it is best to contact your veterinarian. Your vet can perform an intradermal allergy test, injecting small amounts of potential allergens into the skin on your horse’s neck to observe reactions.
You can also support your horse’s comfort with soothing grooming products found in the horse grooming category.
It is usually not necessary or effective to administer an antihistamine. If your horse’s hives are itchy, you can help relieve discomfort by compressing the affected area with a cloth soaked in cool water or diluted apple cider vinegar.
Repeated instances of hives can escalate to angioedema, which presents as severe swelling that may affect the muzzle or eyelids. Contact your veterinarian immediately if your horse’s symptoms worsen or if they appear to have difficulty breathing.
