The skull, containing numerous fused bones, gives shape to your horse’s head, facilitates jaw movement, and envelops the fragile brain to offer protection from trauma. Skull injuries commonly occur from head trauma resulting in fractures, brain injury, and bleeding. Built within the skull are bone encapsulated air pockets known as sinuses. The sinuses moisten inhaled air and trap inhaled particles within secreted mucous. Horses with sinus discomfort develop a nasal discharge. Sinus problems occur with bacterial and viral infections (e.g.: Equine Herpesvirus), allergies, and tooth problems.