Blind vs. ultrasound-guided transgluteal pudendal nerve block: a novel approach in bucks

Pudendal nerve blockade provides effective analgesia for perineal interventions in veterinary practice. Blind blockade techniques based on anatomical landmarks are widely used but carry risks of inaccuracy and complications, whereas ultrasound guidance may enhance precision. This study aimed to describe a novel blind transgluteal pudendal nerve block in bucks, establish an ultrasound-guided approach for targeted deposition of local anesthetic around the common trunk of the pudendal nerve, and compare the efficacy, onset, duration of analgesia, and potential complications of the two techniques. Five adult buck cadavers were used for anatomical evaluation and identification of the relevant landmarks for the transgluteal approach. Eight healthy adult bucks (mean body weight, 30.5 ± 8.4 kg; mean age, 36 ± 6 months) were included in a crossover study in which blind and ultrasound-guided pudendal nerve blocks were performed bilaterally, with a minimum 14-day interval between techniques. Each block was performed using 3 mL of 2% lidocaine hydrochloride per side. The efficacy of each technique was assessed by serial pin-prick testing, and the onset and duration of analgesia were recorded. Both the blind and the ultrasound-guided techniques were successfully performed in all animals. The pudendal nerve and its relation to the sacrotuberal ligament and pudendal vessels were consistently identified sonographically, enabling accurate needle placement. In the blind approach, the optimized point of insertion based on anatomical landmarks allowed reproducible access to the pudendal nerve, although inadvertent vascular penetration occurred during 2 of the 16 blind needle punctures (12.5%). Ultrasound-guided pudendal nerve block using 2% lidocaine hydrochloride demonstrated a shorter onset of analgesia (5.3 ± 1.2 min) compared to the blind technique (10.4 ± 1.5 min; p < 0.05) and provided a longer duration of analgesia (120 ± 15 min vs. 75.2 ± 12.5 min; p = 0.02). Ultrasound-guided pudendal nerve blockade offers faster onset, prolonged duration of analgesia, and greater safety compared to the blind technique. Nevertheless, the newly developed blind transgluteal approach represents a simple, reproducible, and clinically feasible alternative when ultrasound equipment is unavailable, broadening the practical applicability of pudendal nerve block in bucks.