Abstract
Canine nasal carcinomas are often treated with radiotherapy. Presence of lysis of the cribriform plate by tumor invasion (stage 4 by modified Adams's staging system) is a well-known prognostic factor. In this study, dogs with stage 4 disease were divided into two subgroups based on the presence or absence of midline shift of the olfactory or frontal lobes of the brain (Stage 4a: without presence of midline shift. Stage 4b: with midline shift). The median survival time of dogs with midline shift was significantly shorter than that of dogs without midline shift (64 vs. 208 days). Our results indicate that the finding of a midline shift might have a prognostic significance in dogs with nasal carcinoma treated with radiotherapy.