Single-site ventral distal paravertebral block is an effective method of anesthetizing the bovine paralumbar fossa.

OBJECTIVE: To evaluate the efficacy of a single-site ventral distal paravertebral (SS-VDP) block at vertebrae L1 or L2 for regional anesthesia of the bovine paralumbar fossa and characterize subsequent thoracolumbar spinal nerve staining. METHODS: After institutional IACUC approval, 8 healthy 5-month-old Holstein steers received SS-VDP block in a blinded, randomized crossover design at L1 or L2 on each side with 6 mg/kg of 2% lidocaine with 1 mg of methylene blue dye. Anesthesia was assessed along the traditional paralumbar fossa incision site. Calves were euthanized for an unrelated study, and carcasses were dissected to characterize dye spread across thoracolumbar spinal nerves. Block success and staining patterns of spinal nerves were compared between groups via contingency tables and Fisher exact tests. Significance was set at P < .05. RESULTS: SS-VDP injection at either location (vertebrae L1 or L2) produced successful anesthesia of the paralumbar fossa with an overall block success of 75%. Both approaches consistently stained spinal nerves T13, L1, and L2, though an L1 approach resulted in more consistent staining of T13 compared to L2. CONCLUSIONS: SS-VDP block at vertebrae L1 or L2 provided regional anesthesia of the bovine paralumbar fossa. Hypaxial musculature and spinal nerve anatomy of the bovid closely mirrors that of other species, indicating that SS-VDP block is a variant of a quadratus lumborum fascial plane block. CLINICAL RELEVANCE: SS-VDP block provided an alternative to traditional approaches of anesthetizing the bovine paralumbar fossa that require multiple injections and may improve patient welfare by increasing efficiency and practitioner safety.