Sudden swelling of the eyelids is an allergic reaction, most often to insect bites or ingredients in foods. The lids appear fluid-filled, soft, and puffy, and the dog itches and rubs his face. The reaction may be accompanied by hives in which the hair stands out erect in little patches all over the body. This is not a serious problem. It is of short duration and improves when the allergen is removed.
Treatment: Simple cases can be treated with eye drops or ointments containing a corticosteroid prescribed by your veterinarian. Your veterinarian may also suggest an oral antihistamine to reduce the allergic response.