Assessment of the Effective Tissue Concentrations of Injectable Lidocaine and a Lidocaine-Impregnated Latex Band for Castration in Calves

Abstract

This study aimed to assess the effective tissue concentrations of the current standard of care for pain mitigation in calves during castration (injectable lidocaine) and to assess the ability of a lidocaine-loaded elastration band (LLB) to deliver effective concentrations into the scrotal tissue over time. This study comprised two different trials: (1) effective concentrations of injectable lidocaine in the scrotal tissue; and (2) the in vivo delivery of effective concentrations of lidocaine from LLBs placed on the calf scrotums. Sensation in the scrotal tissue was assessed by electrocutaneous stimulation. Injectable lidocaine allowed for short-term anesthesia for up to 60 min, highlighting the importance of finding additional strategies to mitigate long-term pain. An elastomeric ligation band impregnated with lidocaine could provide a suitable alternative, as it yielded tissue levels of lidocaine that approached EC50 and exceeded EC95 at 2 and 72 h following application, respectively, and remained above those levels for at least 28 days after application. Further studies are warranted to compare the use of LLBs to injectable local anesthetics.

Efficacy of a Lidocaine-Impregnated Elastrator Band for Castration and Tail Docking in Lambs

“…Previous work on the LLB used in the present study has demonstrated that these bands are able to effectively achieve therapeutic doses in the tissues studied over a 28-day period [21][22][23]. The goal of the present study was to compare castration and tail-docking efficacy between lidocaine-impregnated ligation bands and control bands under field conditions and to identify the benefits of pain control provided the LLB, with a focus on time to casting and ADG.…”

“…Control bands showed an increase in ADG between d 14 to 21 following castration and tail docking compared to LLB-treated animals. Other studies have noted that, in the absence of analgesia, a reduction in feeding behavior and growth occurs over the subsequent days following the procedure; however, compensatory growth in the weeks following the procedure occurs, as most of the pain has diminished from the tail and scrotum site [18,23]. Although compensatory weight gain occurs in control lambs, it is possible that carcass quality (fat vs. lean muscle and muscle development) may be influenced [27].…”

“…Recently, a latex elastration device was developed by Chinook Contract Research Inc. that has lidocaine impregnated directly into the band [21][22][23]. This band allows for the release of lidocaine at the site of application, with the aid of a tissue permeator.…”

“…This band allows for the release of lidocaine at the site of application, with the aid of a tissue permeator. Importantly, the limitations associated with the traditionally poor diffusion and delivery of lidocaine transdermally [24] have been shown to be mitigated through the use of permeability enhancers [25], which can lead to improved long-term pain relief, which has been recently demonstrated in lambs [22] and calves [23]. However, despite other studies demonstrating efficacy in offering local anesthesia starting 30 min to 28 days after application [17,22], large field studies have not been performed to evaluate the efficacy in casting success and weight gain.…”