Transverse CT of a horse head at the level of Triadan 09. The horse had exodontia of 109 because of dental sinusitis 2 months previously but re-presented with an ipsilateral ventral nasal conchal bulla infection. The VCS contains hypoattenuating material with interspersed gas (shown to be inspissated exudate). The partly-healed post-extraction alveolus contains some food (star) and has grossly thickened and remodeled bone caused by the prior apical infection and exodontia. The bony septum connecting the alveolus and infraorbital canal (white arrow) is much thicker than on the contralateral side, as is its overlying mucosa. The maxillary bone (yellow arrow) is also grossly thickened. L, left; R, right.