The guttural pouches are a structure unique to horses and a few other species. They are diverticula of the auditory tube below the cranial base. Via the auditory tube, the guttural pouches are openly connected to the nasal pharynx. Thus, infectious agents can advance into the guttural pouches. Swelling in the caudal area of the jowl or unilateral bloody or purulent nasal discharge indicate an infection of the guttural pouch and are an urgent indication for guttural pouch endoscopy.