Comparison of intraoperative pain responses following intratesticular or mesorchial injection of lidocaine in standing horses undergoing laparoscopic cryptorchidectomy

OBJECTIVE: To compare pain responses in stallions undergoing standing laparoscopic cryptorchidectomy following intratesticular or mesorchial infiltration of lidocaine. DESIGN: Clinical trial. ANIMALS: 20 stallions with 1 or 2 undescended testes. PROCEDURES: Standing horses were administered a nonsteroidal anti-inflammatory drug and a caudal epidural injection of detomidine hydrochloride and underwent laparoscopic cryptorchidectomy. The undescended testis (1/horse) was grasped to determine the preoperative pain response (present vs absent) and assess severity of pain (by use of a visual analog scale VAS]). The undescended testis or its mesorchium was injected with 2% lidocaine (10 mL); saline (0.9% NaCl) solution (10 mL) was injected in the untreated structure. Presence and severity of pain was determined by 2 individuals as the testis was grasped following infiltration and at the times of ligature placement and transection of the spermatic cord. Serum cortisol concentration was analyzed preoperatively, after ligation, and after transection. Presence or absence of signs of pain, severity of pain, and serum cortisol concentrations were compared within and between treatment groups. RESULTS: Detection of signs of pain and VAS pain scores did not differ between observers at any time point. Perceived pain responses associated with ligature placement differed significantly from preoperative responses. Pain responses and serum cortisol concentrations after intratesticular and mesorchial infiltration of lidocaine did not differ. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that intratesticular or mesorchial infiltration of lidocaine combined with administration of a nonsteroidal anti-inflammatory drug and caudal epidural injection of detomidine provides adequate analgesia in standing stallions undergoing laparoscopic cryptorchidectomy.