Sonography is a convenient, non-invasive diagnostic modality in small ruminants, often used in reproductive management, internal medicine, and surgery. Pregnancy diagnostics and imaging anatomy and pathology of organs, such as neoplasia, are major applications. Urolithiasis is one of the most common causes of death in male sheep and goats, for which sonography is the diagnostic modality of choice. Although ultrasound-imaging techniques for kidneys, ureters, and urinary bladder in small ruminants have been described previously, this study focuses on reporting the imaging technique of the extra-pelvic portion of the urethra, as nearly all the cases of obstructive urolithiasis result from urinary stones in this part. Thirty-three Lacaune-crossbred lambs were examined using a 12 MHz linear probe in laterally recumbent animals. Using this technique, the urethral lumen could be visualised through its entire course in all lambs.

ZusammenfassungEin beim männlichen kleinen Wiederkäuer nicht selten beobachtetes Krankheitsgeschehen ist eine Harnabsatzstörung. Für die prognostische Einschätzung und die Wahl einer möglichst erfolgversprechenden Therapie ist die genaue Kenntnis der zugrundeliegenden Ätiologie unabdingbar. Zu den häufigen Ursachen einer Harnabsatzstörung beim Bock gehören eine obstruktive Urolithiasis, Traumata des Penis und entzündliche Veränderungen der Urethra oder Blase. Neben der klinischen Untersuchung stellen bildgebende Verfahren das diagnostische Mittel der Wahl dar. Da sich eine röntgenologische Darstellung der Harnwege in der Praxis häufig nicht durchführen lässt, hat dieser Artikel das Ziel, die sonographische Untersuchung des unteren Harntrakts beim Bocklamm zu beschreiben.

Early castration of male small ruminants is regarded as a risk factor for urolithiasis, although the underlying correlations are still unclear. One possible reason is a deferred development of the penis and the urethra after castration. Therefore, we examined the penis and urethra of castrated and intact lambs by ultrasonography to determine the correlation between urethral area and penile cross-sectional area. Ultrasonography was performed in 6-month-old Lacaune crossbred lambs (early castrated, late castrated, and intact; each group, n = 11). Sectional images at 5 locations (glans penis, penile urethra, distal and proximal sigmoid flexure, and ischial arch) were obtained to determine the urethral and penile diameters. Urethral and penile cross-sectional areas were calculated. Grey-scale analysis of ultrasound images was performed to evaluate possible differences in the penile texture between the groups. Correlation analyses between both cross--sectional areas showed a significant general correlation for location 2 in all lambs (R = 0.52; P = 0.003), for location 3 in late-castrated lambs, and for location 5 in early-castrated lambs. Statistically significant correlations between the penile and the urethral area of castrated and intact lambs were not evident. Therefore, measurement of the penile cross-sectional area alone does not allow for accurate estimation of urethral size. Statistically significant differences concerning the grey-scale analysis between the groups were also not detectable.Thus, simplification of the formerly presented ultrasonographic examination of the urethra is not recommended. In animals at a risk of obstructive urolithiasis, complete urethral examination is essential.