Frontal sinusitis may occur immediately after dehorning while the site is still open or months later after the dehorning site has healed. The condition is most often unilateral. Signs may include anorexia, pyrexia, unilateral or bilateral nasal discharge, changes in air flow through the nasal passages, and foul breath. Head carriage may be abnormal. In longstanding cases of frontal sinusitis, there may be distortion of the frontal bone, exophthalmos, and neurologic signs.
Sinusitis is treated by draining the affected sinus. Trephine sites should be selected carefully, using appropriate anatomic landmarks. If an infected tooth is the cause of maxillary sinusitis, the tooth can be repelled through a sinusotomy site created with a trephine. Once drainage has been established, the sinus can be lavaged daily with antiseptic solutions. Treatment with parenteral antibiotics is indicated if systemic signs are present. NSAIDs can be given for pain relief, if needed. The prognosis is guarded.