Epistaxis and Destructive Computed Tomographic Features in Canine Nasal Transitional Carcinoma: Frequent Cribriform Plate Destruction but Uncommon CT-Detected Brain Parenchymal Involvement.

Nasal transitional carcinoma (TC) is one of the most common epithelial nasal tumors in dogs, but systematic descriptions of its clinical and computed tomographic (CT) features are limited. This multicenter retrospective study characterized the clinical and CT features of histopathologically confirmed nasal TC in 16 dogs examined at four animal hospitals between July 2014 and January 2024. Signalment, clinical signs, CT findings, and follow-up information were summarized descriptively. Epistaxis was the most common clinical sign (12/16, 75%). All tumors involved the caudal nasal cavity, and extension to adjacent structures or most commonly affected the maxillary recess (14/16, 88%), orbit (11/16, 69%), and nasal choanae (10/16, 63%). Most tumors exhibited destructive growth (15/16, 94%) with frequent cribriform plate lysis (12/16, 75%). Cranial vault invasion was identified in 12 dogs (75%), whereas CT-detected brain parenchymal involvement was present in only 2 dogs (13%). Intralesional non-enhancing fluid-attenuating regions consistent with necrosis or cystic change and peritumoral fluid accumulation were observed in 12 (75%) and 10 dogs (63%), respectively, and intralesional calcification was absent in all dogs. These results provide a frequency-based CT reference pattern for canine nasal TC; however, the findings are not specific for this tumor type, and histopathological examination remains necessary for definitive diagnosis.