A new method of administering local anesthesia for calf disbudding: Findings from a comparative on-farm study in New Zealand

Abstract

Anesthesia of the horn bud for calf disbudding commonly is attained by injection of local anesthetic over branches of the cornual nerve, with anesthesia achieved in 3 to 20 min. With experienced and trained staff, this method is effective in 88 to 100% of calves. Variability in response and time of onset can compromise calf welfare if calves are disbudded before anesthesia is attained. Proposed legislative reliance on effective local anesthetic as the minimal method of pain relief for calves at disbudding means that administration of local anesthetic must achieve a repeatable level and rapid onset of analgesia. We describe an alternative method of local anesthesia administration that uses local site infiltration of anesthetic over the horn bud. However, this method has not yet been scientifically validated. This study assessed differences between disbudding using the cornual nerve block and disbudding with local anesthesia administered by local site infiltration. Efficacy of local anesthesia was assessed at 30-s intervals after administration by absence of reaction to 3 consecutive needle pricks over the horn buds. Behavior indicating pain was assessed during disbudding and scored from 0 to 3. Calf behavior was also recorded for 3 h after disbudding. Accelerometer data loggers were fitted to each calf for 24 h before and after disbudding to assess lying and standing times. Median time to cutaneous desensitization for local infiltration was 60 s compared with 225 s for cornual nerve block, and the variance in time to desensitization was less with local infiltration. Calves disbudded under cornual block had a larger behavioral response (indicated by a graded aversive body reaction) than calves disbudded under local infiltration. A multivariable model predicted that the mean body reaction score would be 0.6 for calves disbudded under local infiltration and 1.2 for calves disbudded under cornual block. There was no difference in any behaviors between the treatment groups in the 3 h after disbudding. Method of analgesia had no effect on lying time over the 24 h after disbudding. In this study, local infiltration was at least as effective in providing analgesia for disbudding as the cornual nerve block. Our results suggest that a more consistent, effective level of analgesia during disbudding was achieved using local infiltration and that there was no difference in postoperative expressions of pain.

Behavioral changes in calves 11 days after cautery disbudding: Effect of local anesthesia

“…A reduction in play has been observed 3 h after a lidocaine cornual nerve block in sham-disbudded calves, which may indicate continued discomfort at the injection sites after the anesthesia has worn off (Mintline et al, 2013). However, Bates et al (2019) found no differences in head shaking, head scratching, or head rubbing in the 3 h after lidocaine injection in sham-disbudded calves compared with non-injected controls. Further research is warranted on the physiological and affective consequences of lidocaine.…”

“…In accordance with this theory, calves reduced rubbing their head on objects or pushing it against penmates, in the first 4 h after hot-iron disbudding without local anesthesia (Morisse et al, 1995;Graf and Senn, 1999). However, despite these early findings, subsequent studies observed either no change in time spent rubbing or touching the head against objects or penmates after hot-iron disbudding (Doherty et al, 2007;Mintline et al, 2013;Bates et al, 2019), or have reported more head rubbing in calves disbudded with a hot-iron (Faulkner and Weary, 2000;Heinrich et al, 2010;Stilwell et al, 2012;Huber et al, 2013) or caustic paste (Vickers et al, 2005;Stilwell et al, 2009) compared with non-disbudded calves. Interestingly, however, all the studies that reported more head rubbing defined the behavior entirely or in part as scratching with the hindfeet.…”

Horn bud size of dairy-bred and suckler-bred calves at time of disbudding

“…A number of studies have focused on the acute pain response to cautery disbudding [ 33 – 36 ] and of the benefits of providing local anaesthesia and pain relief [ 12 , 37 – 41 ] at the time of disbudding. Adcock and Tucker [ 36 ] reported that calves disbudded at 3 d versus 35 d of age were more sensitive to pain after disbudding.…”

“…A number of studies have focused on the acute pain response to cautery disbudding [33][34][35][36] and of the Table 2 Effect of sex, age and year on horn bud diameter (mm) and height (mm) of suckler-bred male and female calves at disbudding (n = 191) benefits of providing local anaesthesia and pain relief [12,[37][38][39][40][41] at the time of disbudding. Adcock and Tucker [36] reported that calves disbudded at 3 d versus 35 d of age were more sensitive to pain after disbudding.…”

Why Effective Pain Management Remains a Challenge

“…Pharmacological agents used in the management of pain include opioids, nonsteroidal anti-inflammatory drugs, steroidal anti-inflammatory drugs, and local anesthetics [25]. Additionally, tranquilizers, corticosteroids, tricyclic antidepressants and antiepileptic medications (topical capsaicin, mexiletine, and N-methyl-d-aspartate receptor antagonists), serotonin norepinephrine reuptake inhibitors, calcium channel α2-δ ligands, topicals, anticonvulsants, and transdermal substances are included in the pain management regimen as adjuvants to analgesics depending on the type and severity of pain [26][27][28][29]. Nonpharmacological management of pain involves the use of suitable housing, bed rest, gentle handling and manipulation (massage, osteopathic and chiropractic), meditative movements (such as Tai Chi and yoga), and diets [30,31].…”