Horse allergies are often associated with respiratory symptoms such as coughing, raspy breathing, head shaking and slight exercise intolerance. As the allergic condition advances, the coughing becomes more progressively frequent and deeper. Runny nose and watery eyes are often early signs of allergies. Dermatological symptoms are also common. These include itching, recurrent hives or small flat-topped bumps (wheals), patchy hair loss due to excessive rubbing or crusting.

One of the most common allergy in horses is the Summer Dermatitis, a seasonal skin problem, caused by the bite of Culicoides. The symptomatology is very typical, with lesions in the neck, face and tail during summer period.