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

Abstract

ObjectiveTo determine the onset, duration and efficacy of four local anesthetic methods for the horn bud in calves. Study designCrossover study. AnimalsEight, 2 month-old Holstein Friesian bull calves. MethodsCalves 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. ResultsThe 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 relevanceThe 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.