List of Horse Allergies

Allergies are caused by the immune system overreacting to a harmless substance. (See References 1) Equine allergies cause an array of symptoms that resemble other equine illnesses, making allergies challenging to diagnose. Typical symptoms include running eyes, coughing, swellings on the shoulders and general apathy or behavior changes. (See References 2) Horses spend most of their time in areas prone to dust, mold spores, plants and insects that may cause allergic reactions, and horses have not evolved to tolerate the conditions in which they are kept. (See References 1) Some equine allergies may take years to develop, and all breeds of horses are equally susceptible. (See References 2)

  1. Skin Allergies

    • Skin allergies are the most common equine allergies and are generally caused by food allergies or insect bites, particularly gnats and mosquitoes. Horses tend to develop hives on the neck and shoulders, and fever may result. Because of itchiness, horses will rub the affected area, creating a bald patch. Although treatment for skin allergies is rarely required, corticosteroids provide relief from itching and, if a cause of the allergy cannot be determined, veterinarians can administer allergy shots that help reduce the allergic reaction. (See References 2)

    Respiratory Allergies

    • Veterinarians often call equine respiratory allergies heaves, and heaves manifest as coughing, nasal discharge, wheezing and difficulty running or exercising. Heaves resemble symptoms of asthma in people, and treatment is essential, as severe cases may cause weight loss. Treatment of heaves should begin by attempting to identify the source of the problem. Dust, mold spores and pollen may all be culprits and may come from the horse's bedding or hay. Whenever possible, remove the source of the allergy. For example, change the horse's bedding or soak its hay in water to remove allergens. If environmental changes do not resolve the problem, your veterinarian may prescribe corticosteroids. (See References 2) However, since corticosteroids may have harmful side effects and do not treat but only mask the symptoms. Correcting the cause of the allergy is preferable. (See References 1)

    Headshaking

    • As the name suggests, horses affected by headshaking shake their heads constantly and violently, especially while being ridden. They may rub their heads on the ground or bury their faces in the tails of other horses. (See References 3) Headshaking is difficult to treat and causes the horse to be unrideable. Although there are multiple causes of headshaking, because horses mainly show symptoms in the spring and summer, one cause may be allergies, and these horses should respond to corticosteroid treatment. (See References 4)

    Uticaria

    • Horses affected by uticaria develop oozing hives and may, over time, also become depressed. The sores caused by uticaria may result in secondary infection or cause the horse to be unrideable. Skin irritation can cause uticaria, but food allergies are the primary cause. Changes in diet and bedding, corticosteroid treatments and allergy shots may alleviate uticaria. (See References 4)