Anatomical and ultrasonographic study of the femoral nerve within the iliopsoas muscle in beagle dogs and cats.

OBJECTIVES

An ultrasound (US)-guided ventral suprainguinal approach to block the femoral nerve (FN) within the iliopsoas muscle (IPM) has recently been described in dogs. The goal of the present study was to provide the operator with additional information to locate the FN within the IPM in dogs and cats using US.

STUDY DESIGN

The study was carried out in three phases: a dissection of the FN (phase 1); an in vivo US-assisted nerve study (phase 2), and an anatomical cross-sectional study (phase 3).

ANIMALS

Nine healthy adult beagle dogs and nine healthy adult cats.

METHODS

Dissections were performed to investigate the anatomical characteristics of the FN and its related structures in one dog and one cat. Ultrasound scans of the left and right FN were performed in eight dogs and eight cats. The FN diameter and the distance between the FN and the external iliac artery (EIA) in US images and in anatomical cryosections were measured.

RESULTS

The median FN diameter did not differ significantly between cats and dogs (1.1 mm versus 1.0 mm) or between the two techniques (US versus anatomical cross-sectional study) (1.1 mm versus 1.1 mm in dogs; 1.0 mm versus 1.1 mm in cats). The US and anatomical measurements of the median distances between the FN and EIA differed significantly between dogs and cats (8.2 mm versus 5.8 mm by US; 5.7 mm versus 4.8 mm in the anatomical study).

CONCLUSIONS AND CLINICAL RELEVANCE

The distance between the EIA and FN is reproducible in beagle dogs and cats and can be used in locating the FN within the IPM.