"Tis the Season for Allergies to Make a Horse's Life Miserable

Horse silhouetted against a hazy summer pasture.
Horse silhouetted against a hazy summer pasture. Horse Crazy

Newsdate: Thursday, May 6, 2021 - 11:35 am
Location: Gilroy, CA

Spring weather has definitely arrived and nature is in the process of kicking everything up a notch. This includes all kinds of environmental situations that can cause allergies in horses. As spring days wind down and summer arrives, many horse owners must deal with horse health issues related to allergies.

Horse with a skin condition due to allergies.

Horse with a skin condition due to allergies

If a horse has a healthy immune system, fighting off allergens will be easy, but, if the immune system is compromised in any way, allergies can become a serious problem.
© 2017 by Sharon Morris New window.

When a horse has an allergic reaction, his immune system perceives a threat from something harmless and mounts a huge response against an invader. Instead of wiping out the troublesome microorganisms, this reaction can actually damage the horse's body tissues.

Additionally, as the horse become hypersensitive to a specific allergen, his body can boost its defense system against it, so the next time he's exposed to it, the reaction is likely to be quicker and stronger.

Many environmental allergies are seasonal, depending on which insects are active and which plants are blooming. These allergic reactions can be anything from mild to life-threatening.

A horse that is allergic often shows the following signs of an allergic reaction:

  • Persistent coughing which may be accompanied by wheezing
  • Watery nasal discharge
  • Signs of skin irritation
  • Evidence of physical discomfort
  • Respiratory problems
  • Diarrhea

Allergies are related to many normal substances in the environment including sensitivity to inhalants produced by pollens, grasses, weeds, shrubs, molds, oats, wheat, barley, corn, and barn dust, as well as ingredients in commercial horse foods.

Certain foods, feeds, grains, hay varieties, and nutritional supplements may trigger allergies. Other causes include reaction to chemicals in tack supplies, insect saliva, and products used in the stable area.

Skin allergies are often caused by insect bites resulting in hives or welts as a result of the build-up of proteins called antibodies. Insect

Horse allergies can take years to develop. Undetected allergies are difficult to prevent and diagnose initially. If a horse has a healthy immune system, fighting off allergens will be easy, but, if the immune system is compromised in any way, allergies can become a serious problem.

According to Christine Rees, DVM, a board-certified veterinary dermatologist “Allergies are not curable, but they are manageable.” To maintain better horse health a wise owner will learn how to recognize the signs of allergies and then figure out the best course of action to prevent allergic reactions from happening."

Two of the most common types of triggers for allergies during the spring and summer months include insect bites and environmental allergens.

Swelling around an insect bite is a normal inflammatory response, but an itchy rash, loss of hair patches, or a case of hives is more likely a true allergic response. The oozing rash characteristic of sweet itch, or summer eczema, is an allergic reaction to the bites of tiny Culicoides midges, which many people call no-see-ums. Proteins in the saliva of the midges trigger the reaction in the horse.

Weeds and grasses, along with insects, also cause the most trouble for horses, Dr. Rees says. Common environmental allergens include molds and dust mites as well as pollen from cocklebur, ragweed and various other plants (which are prevalent in the spring/summer months). Some horses are allergic to pollen from Bermuda grass, which is widespread in southern states and is sometimes used for pasture.< p/>

Keeping the environment clean and insect free, and changing the bedding often is key to preventing allergies. Hay, grain, and bedding are major sources of mold spores and particles in the barn air. When possible, store hay and bedding in a separate building rather than in a barn loft or area. In some cases, using shredded paper or rubber mats for bedding will help prevent or resolve allergy problems.

Elimination of foods that cause allergy symptoms, and following a recommended diet for horses with allergy problems is helpful when food allergies are involved.

The best form of treatment is avoidance of the offending allergens, although in reality, this may not be possible. Some allergies naturally dissipate with time, but steroids and other drugs are often necessary to counteract the unpleasant symptoms and effects of allergies. If the use of drugs is necessary, the horse's condition should be thoroughly evaluated by a veterinarian before the treatment is started.

Prolonged use of drugs can have serious side effects, so proper testing to determine the source of the allergic reaction is important. Having ruled out other possible maladies, blood may be drawn and sent to a laboratory for diagnostic evaluation. The horse's serum will be tested for sensitivity to a number of possible allergens including grasses, weeds, molds, pollens, barn dust and a number of food types and ingredients used in horse food preparations.

Based on the results of the allergy test, the same allergens to which the horse tested sensitive are injected in increasing concentrations. This builds the horse's tolerance to the allergens so he can live more comfortably in his environment

About the Author

Flossie Sellers

Author picture

As an animal lover since childhood, Flossie was delighted when Mark, the CEO and developer of EquiMed asked her to join his team of contributors.

She enrolled in My Horse University at Michigan State and completed a number of courses in everything related to horse health, nutrition, diseases and conditions, medications, hoof and dental care, barn safety, and first aid.

Staying up-to-date on the latest developments in horse care and equine health is now a habit, and she enjoys sharing a wealth of information with horse owners everywhere.