Horse Allergies & Symptoms

When a horse reacts negatively to substances it eats or comes into contact with, it may be suffering from an allergic reaction. Allergic reactions to a substance can happen at any time, even if the horse has come into contact with the particular allergen before with no adverse effects. A number of items in a horse's environment can cause an allergic reaction. Some of the symptoms the horse owner may see are hives, alopecia (hair loss), coughing and scratching.

  1. Hives

    • Hives is the appearance of round, raised bumps on the skin, ranging in size from less than an inch to several inches. The hair sticks out in patches over parts of the body. There may be swelling of the face or eyelids. These bumps, which are not painful, pit with pressure. The horse may or may not itch.
      Episodes of hives that come and go and last only a few hours are generally caused by inhaled allergens, or less commonly, by feed allergies. Inhaled allergens known to cause hives in horses include the down of bird feathers, pollens of numerous trees, bushes, plants, weeds, grasses, dust and molds.
      Vaccinations and injected drugs can occasionally cause hives.

    Alopecia

    • Alopecia, or hair loss, is a common symptom of contact dermatitis--allergies caused by contact to the skin. The greatest hair loss occurs around the muzzle, lower legs, feet and in sites that are exposed to horse tack. Common irritants are acids alkalis, insecticides, detergents, solvents, soaps and petroleum by-products. Rubber bits can also cause reactions around the mouth. The site of the reaction frequently indicates the cause of the allergy.

    Coughing

    • A cough is a reflex produced by an irritation or allergen of the airways and is usually part of a condition called heaves. Coughs are caused by infectious diseases, smoke and other inhaled irritants, grass seeds and foreign objects in the airway.

    Scratching

    • Many horses, in an attempt to relieve the irritation caused by the allergen, will excessively scratch and bite at the site. Secondary infections commonly develop when the horse continually bites and scratches, compounding the condition.

    Nasal Discharge

    • A watery discharge with sneezing is typically due to irritants such as dust or vegetable matter trapped on the mucous membranes. Environmental allergies may occasionally produce a clear nasal discharge.