Local Anaesthesia of the Bovine Tarsus: A Cadaver Study Comparing Anatomical Landmark-Based and Ultrasound-Guided Nerve Blocks

Surgical procedures involving the tarsal joint are common in cattle. Indications for tarsal surgery include joint lavage, arthrotomy, the treatment of injuries, and hygromas. The goal of the present study was to lay the foundation for a reliable method of nerve block desensitisation of the bovine tarsus. Two nerve block techniques were simulated in an anatomical cadaver study on six bovine pelvic limbs for each technique. In the first technique, injection sites were based on palpation of anatomical structures, and in the second technique, ultrasound guidance was used to localise the nerves. After injection of dye (methylene blue) solution using anatomical landmark-based or ultrasound guidance methods, the 12 cadaver limbs were dissected, and the effectiveness of sham anaesthesia was determined based on the proximity of the dye solution to the nerve and the length of its distribution along the nerve. The ultrasound-guided local anaesthesia required significantly more time to perform compared with nerve blocks based on anatomical landmarks. However, the dye reached the target area in 25 of 30 application sites using ultrasound-guided local anaesthesia compared with 13 of 30 sites using the anatomical landmark-based technique. Ultrasonographic guidance led to fewer inadvertent intravascular and intramuscular injections. In conclusion, the ultrasound-guided local anaesthesia is a promising alternative to general anaesthesia, epidural, and intravenous regional anaesthesia for surgical procedures of the bovine tarsal joint and eliminates the disadvantages of other anaesthetic techniques, like general anaesthesia and intravenous regional anaesthesia. The practicability and utility of this technique still require validation in vivo.