Computed tomography may be helpful in discriminating grass awn foreign body rhinitis from non-foreign body rhinitis in dogs.

Grass awn foreign bodies are a common cause of rhinitis in dogs.  Early detection and complete removal of these foreign bodies are important for minimizing risks of long term complications. The objective of this retrospective, descriptive cross-sectional study was to determine whether discriminating CT findings exist between dogs with grass awn foreign body rhinitis and dogs with non-foreign body rhinitis. Computed tomography scans of 47 dogs with a confirmed diagnosis of non-foreign body rhinitis (25 cases) or of a nasal grass awn foreign body (22 cases) were reviewed. In the latter group, grass seeds were visualized directly on CT images for one of 22 (5%) cases. Focal lysis was more strongly associated with the presence of a grass awn foreign body (P = .012, LR = 3.0) and widespread lysis (involving more than one-third of the nasal cavity and/or bilateral) appeared associated with non-foreign body rhinitis (P = .046, LR = 2.0). Maxillary recess filling was associated with non-foreign body rhinitis (LR = 4.4) as was widespread lysis (LR = 2.0). Findings supported prioritizing grass awn foreign body rhinitis as a differential diagnosis for dogs with the former CT characteristics, even if a grass awn cannot be directly visualized.