The Sinuses and Paranasal Sinuses are extensive air-filled structures in the horse which probably evolved to allow the horse’s head to achieve the size needed to accommodate its large array of molars and premolars, but with minimal added weight.
Sinus cavities are located on each side of the horse’s head, above, below and between the eyes, and extending down the face to a point level with the end of the very obvious facial crest. Most of the horse’s cheek teeth, premolars, and molars extend into the sinus cavities and are contained within bone that forms the floor of the sinuses. Because the bone over the sinuses is thin, it is readily distorted by internal pressure from a disease process. Most often this is manifested with apical tooth root infections bursting into the sinuses leading to a foetid nasal discharge.
Surgical entry to the sinuses is something we can perform with standing sedation and local anaesthesia to facilitate flushing of infective material and removal of other lesions such as Sinus Cysts.