Onset, duration and efficacy of four methods of local anesthesia of the horn bud in calves

Abstract

Objective: To determine the onset, duration and efficacy of four local anesthetic methods for the horn bud in calves.

Study design: Crossover study.

Animals: Eight, 2 month-old Holstein Friesian bull calves.

Methods: Calves were subjected to one of the four following treatments: 1) cornual nerve block (C), 2) ring block (R), 3) cornual nerve block using a percutaneous jet delivery technique (JET) all using 2% lidocaine with epinephrine (0.01 mg mL(-1)), and 4) topical eutectic mixture of local anesthetics (EMLA) cream. A peripheral nerve stimulator was used to assess cutaneous sensation over the horn bud using a graded response. Onset, duration and efficacy of anesthesia were determined.

Results: The efficacy of the blocks was as follows: C 87.5%, R 100%, JET 37.5%, EMLA 0%. The median onset time and duration of anesthesia for C and R were: 2 (range 0.5-5) and 304 (range 107-512), and 3.25 (range 1-9) and 147 (range 62-299) minutes, respectively. Three of eight JET injections had a median onset and duration of 8 (range 0.5-9) and 132 (range 101-155) minutes, respectively. The duration of the C block was significantly longer than the R block (p = 0.047).

Conclusions and clinical relevance: The relatively rapid onset and long duration of anesthesia with C or R blocks using 2% lidocaine with epinephrine validates their practical use in dehorning calves while jet injection and EMLA cream provided insufficient analgesia to be clinically useful. The efficacy of the C block requires further study.