Ultrasound Examination of the Penile Urethra in Healthy Non‐Castrated Texel Lambs Confined for Fattening

Abstract

This study aimed to determine, using ultrasonography, the width of the penile urethral lumen in Texel lambs and to compare two types of linear probes. Thirty healthy, uncastrated lambs kept in confinement for fattening were subjected to ultrasound examinations at 60, 120, and 150 days of age. The penile urethra was examined at four sites: proximal urethra, sigmoid flexure, distal to the sigmoid flexure, and distal urethra. The images were obtained in B-mode with cross sections using two types of linear probes: for external use (external probe: EP; 13 MHz) and for transrectal use in large animals (rectal probe: RP; 10 MHz). Data were analyzed using a two-way repeated-measures ANOVA. The image quality was superior when using EP. The urethra was identified as a circular or elliptical structure with a slightly hyperechoic wall and an anechoic lumen. At the four anatomical sites, the width of the urethra increased with age (p < 0.001), and the values measured using RP were higher (p < 0.05). With EP, the lumen width was 1.0‒3.4 mm in the proximal urethra, 0.6‒3.3 mm in the sigmoid flexure, 0.5‒2.9 mm in the region distal to the sigmoid flexure, and 0.7‒2.5 mm in the distal urethra; with RP, these values were 0.8‒3.9, 0.6‒3.3, 0.7‒3.3, and 0.8‒2.9 mm, respectively. Ultrasound examination of the penile urethra is feasible, and the values obtained for the lumen width can be accepted as physiological standards for comparison. This examination can be performed with a linear RP in large animals.

The authors' abstract, as published at the source. Veterinary Radiology & Ultrasound, 2026 · DOI ↗