Horse presented for a paranasal sinus cyst. A. Horse at presentation. Note the marked facial deformity due to enlargement and growth of the cyst, resulting in distortion of the facial bones (asterisk). B. Intraoperative view during surgical removal of the paranasal sinus cyst through a frontal sinusotomy. Note that a portion of the cyst has been removed; the remainder is indicated by the asterisk. C. Postoperative view of the horse, demonstrating staple closure of the sinusotomy bone flap (asterisk).