Evaluation of three approaches for performing ultrasonography-guided anesthetic blockade of the femoral nerve in calves

Objective—To develop a practical ultrasonography-guided injection approach to anesthetic blockade of the femoral nerve in calves and to assess the method's accuracy. Animals—13 cadavers of 4-week-old male Holstein Friesian calves. Procedures—Detailed topographic and anatomic cross-sectional evaluation of the relevant topography in 3 cadavers was performed to identify optimal injection approaches to the femoral nerve. Three approaches (ventral paravertebral, dorsal paravertebral, and ileal) were evaluated by simulated ultrasonography-guided perineural injection of methylene blue dye in 10 cadavers. Ultrasonographic image quality, number of needle redirections required for correct needle positioning, and injection success as defined through a 3-point grading system were recorded. Results—The dorsal paravertebral approach yielded the best results, compared with the ileal and ventral paravertebral approaches, to properly and adequately stain the targeted nerve. Conclusions and Clinical Relevance—The dorsal paravertebral injection technique appeared to be the best choice for performing a femoral nerve block in calves, although this technique will need to be further evaluated in live calves to determine its effectiveness and clinical usefulness. Diagnostic perineural anesthesia of the femoral nerve in cattle might be helpful in identifying quadriceps muscle involvement in those with complex spastic paresis.