Computed Tomographic Volumetric Analysis of the Nasal Cavities in Domestic Cats ( <i>Felis catus</i> ) and Anatomical Implications for Intranasal Drug Delivery

To perform a computed tomography (CT)-based volumetric assessment of the nasal cavities in domestic cats and to evaluate the relationship between nasal cavity volume and selected morphometric variables. Fifty-six European cats that underwent CT examination of the head were retrospectively included. Three-dimensional segmentation of the right and left nasal cavities was performed using dedicated software. Total, right, and left nasal cavity volumes were measured. Associations between nasal cavity volume and sex, age, and body weight were assessed using multiple linear regression analysis. Bilateral symmetry was evaluated using paired comparisons. Intra-observer reliability was determined using the intraclass correlation coefficient (ICC). Mean total nasal cavity volume was 6.74 ± 1.79 mL. No significant difference was observed between left (3.38 ± 0.92 mL) and right (3.36 ± 0.91 mL) nasal cavity volumes. Male cats exhibited significantly larger nasal cavity volumes than females (8.3 ± 1.7 mL vs. 5.8 ± 1.1 mL; p < 0.001). No significant association was found between nasal cavity volume and age or body weight after adjustment for sex. Intra-observer agreement was excellent (ICC = 0.98). CT-based three-dimensional segmentation provides reliable volumetric assessment of the feline nasal cavities. Significant sexual dimorphism was identified, whereas laterality, age, and body weight had no significant influence on nasal cavity volume. The limited nasal cavity volume supports the use of low-volume, concentrated formulations for intranasal drug delivery in cats.