RT Journal Article T1 Description of an ultrasound-guided technique for pudendal nerve block in sheep A1 López Ramis, Víctor A1 Re, Michela Tatiana A1 Canfrán Arrabe, Susana A1 Arenillas Baquero, Mario A1 Gaspar Simón, Ignacio de A1 Álvarez Gómez De Segura, Ignacio A1 Blanco Murcia, Francisco Javier AB Objective To describe an ultrasound-guided technique for anaesthesia of the pudendal nerve with evaluation of the anatomical spread of a bupivacaine-methylene blue solu tion in sheep. Study design Prospective, experimental study. Animals A total of seven adult experimental sheep and one sheep cadaver. Methods The study had two phases. First, the anatomy and ultrasound imaging of the gluteal region, caudal to the region of tuber coxae was reviewed in one sheep cadaver. Second, in seven healthy sedated sheep, a linear transducer (8e13 MHz) was positioned on the lateral area of the hip to identify pu dendal vessels at the level of the ischial spine ventral to the sacrotuberous ligament. The right and left pudendal nerves area were injected with 0.1 mL kg-1 of a 1:1 solution of bupivacaine-methylene blue. The ultrasound image quality was considered as excellent, good, or poor. Following eutha nasia, both pudendal areas were dissected and the staining of the nerves assessed, expressed as the percentage of success (%) and compared with the chi-square test. Results The relevant ultrasound landmarks were visualized in both areas of all sheep, with an excellent visualization of the landmarks before and during injection in most cases (13/14). On dissection, methylene blue dispersion was observed surrounding the pudendal nerve, with at least 1 cm length in 13/14 cases (93%; the remainder partially stained). No evidence of dye was found around the sciatic nerve in any case nor was there any evidence of haema toma or faecal contamination within the punctured area. Conclusions and clinical relevance Ultrasound-guided in jection with 0.1 mL kg-1 in close proximity to the pudendal nerve at the ischial spine level resulted in a high success rate o nerve staining. This procedure may be a suitable technique for pudendal nerve blockade providing analgesia for common reproductive or perineal surgical procedures in sheep. PB Elsevier SN 1467-2987 YR 2025 FD 2025 LK https://hdl.handle.net/20.500.14352/125276 UL https://hdl.handle.net/20.500.14352/125276 LA eng NO López-Ramis, V., Re, M., Canfrán, S., Arenillas, M., De Gaspar, I., Gómez De Segura, I. A., & Blanco Murcia, J. (2025). Description of an ultrasound-guided technique for pudendal nerve block in sheep. Veterinary Anaesthesia and Analgesia, 52(2), 236-243. https://doi.org/10.1016/j.vaa.2024.11.043 NO Authors contributionsVLR: study design, data acquisition, data interpretation, manuscript preparation. MR: study design, data acquisition, data interpretation, manuscript preparation, revision, and approval. JBM: study design, data acquisition, data interpre tation, manuscript preparation, revision and approval. SC: study design, data interpretation, manuscript preparation, revision and approval. MA: study design, data acquisition, data interpretation, manuscript preparation, revision and approval. IDG: anatomical evaluation and guided dissection. IAGS: study design, data interpretation, manuscript preparation, revision and approval. All authors read and approved the final version of the manuscript. DS Docta Complutense RD 26 feb 2026