# Tomographic Characterization of the European Shorthair Cat Orbital and Infraorbital Regions

## TL;DR

This study provides detailed anatomical measurements of the orbital and infraorbital regions in European Shorthair cats to improve the safety of nerve blocks and surgeries.

## Contribution

A simplified, repeatable method for measuring feline orbital and infraorbital anatomy using standard CT planes, not 3D reconstructions.

## Key findings

- Mean infraorbital canal length was 5.23 ± 0.49 mm, with males having longer canals than females.
- Strong correlations between infraorbital and skull parameters were found, aiding clinical estimations.
- Sex-based differences persisted after adjusting for skull size, indicating proportional anatomical variation.

## Abstract

This study describes the European Shorthair cat’s orbital and infraorbital anatomy to support safer locoregional anesthesia and surgical planning. The objective was to provide reliable anatomical landmarks and reference values, using an approach based on linear measurements taken directly from sagittal, transverse and dorsal CT planes, instead of three-dimensional reconstructions. By analyzing scans from 24 neutered cats, we confirmed that those measurements can be consistently repeated. Mean infraorbital canal length was 5.23 ± 0.49 mm. Significant correlations were observed between infraorbital and skull parameters, which may offer approximate estimations to assist clinical decision-making. After adjustment for skull size, some significant differences between sexes remained.

Accurate knowledge of orbital and infraorbital regions and their relation to pterygopalatine fossa is essential for improving safety and effectiveness of infraorbital and maxillary nerve blocks and for guiding surgical procedures in dentistry. Previous studies relied on multiplanar or three-dimensional reconstructions of computed tomographic (CT) images, requiring additional processing and expertise. Scans from 24 European Shorthair cats were analyzed retrospectively, to provide anatomical landmarks and reference values for orbital and infraorbital regions, using a simplified approach based on linear measurements taken directly from sagittal, transverse and dorsal CT planes. Repeatability of measurements was confirmed, with all parameters showing strong agreement across sessions. Significant differences were observed between mean infraorbital canal length in females (5.02 ± 0.42) and males (5.46 ± 0.46), and skull length in females (88.06 ± 3.16) and males (94.54 ± 4.52). Males exhibited 0.42 mm larger infraorbital major axis. After adjustment for skull size, only selected differences persisted, reflecting proportionally longer skulls in males. This study contributes practical reference data to support the limited safe depth for infraorbital/maxillary nerve blocks and the associated risk of globe penetration if instruments are advanced too far into the infraorbital canal. By proposing this simplified and clinic-ready workflow, our results provide foundation for standardization of feline orbital and infraorbital morphometry.