Equine allergies happen when the immune system overreacts in response to a substance. They can happen any time of the year as well due to different changes in the horse’s environment. Types of Allergies Contact/dermatology allergies Insect allergies Respiratory allergies Food allergies Symptoms of Allergies Hives Itching (mild to severe) Watery, swollen, red, draining eyes Runny nasal discharge Coughing Wheezing Labored breathing Tail rubbing Common Causes of Allergies Feed c