Three Studies Evaluating the Potential for Lidocaine, Bupivacaine or Procaine to Reduce Pain-Related Behaviors following Ring Castration and/or Tail Docking in Lambs.

Alison Small,Ian Colditz,Robin Smith,Manon Fetiveau

doi:10.3390/ani11123583

Abstract

Simple SummaryLambs are routinely castrated and/or tail docked. Local anesthesia could improve lamb welfare, but data on the duration of effect of local anesthetics are not available. This study evaluated the efficacy of lidocaine, procaine, or bupivacaine in terms of the behavioral response to castration and/or tail docking. The benefits of local anesthetics were modest. The effects of procaine appear to last longer than lidocaine, while bupivacaine is slower to take effect but may provide longer-lasting pain relief. The duration of action of local anesthetics is limited in sheep, and detailed behavioral evaluations are required in the first hour post-procedure to observe efficacy.The use of local anesthesia at the time of ring castration and tail docking can improve lamb welfare. However, few local anesthetics are registered for sheep, and data on their duration of effect is limited. Three studies were conducted to evaluate the efficacy of procaine (P), lidocaine (L), and bupivacaine (B) in terms of observed alleviation of behavioral responses to castration and/or tail docking in 10-min blocks in the first 60 min post-treatment. In each study, comparisons were made between two groups of lambs castrated and/or tail docked with rubber rings and either receiving the agent using the NUMNUTS® instrument (N) or receiving no anesthetic agent (RR). Acute pain behavior was lower in NL (n = 28) than RRL (n = 15) males in the first 10 min post-procedure (p < 0.05); lower in NB (n = 16) than RRB (n = 16) males in periods 10–20 min (0.05 < p < 0.01), 20–30 min (p < 0.05) and 40–50 min (0.05 < p < 0.01); lower in NB (n = 16) than RRB (n = 16) females between 20 and 40 min post-procedure (0.05 < p < 0.01); lower in NP (n = 8) than RRP (n = 7) males in period 10–20 min (0.05 < p < 0.01), and lower in NP (n = 9) than RRP (n = 9) females in periods 0–10 min (0.05 < p < 0.01), and 10–40 min (p < 0.05). Benefits were modest, and the effects of procaine appear to last longer than lidocaine, while bupivacaine is slower to take effect than either procaine or lidocaine but may provide longer-lasting pain relief. The duration of action of local anesthetics is short in sheep, and detailed behavioral evaluations are required in the first hour post-procedure to establish efficacy.

Highlights

Castration and tail-docking of lambs are common husbandry practices and are considered to be very painful for the animals [1,2]
All local anesthetic agents provided some mitigation of total acute pain avoidance behaviors (Figure 1)
In male lambs provided with lidocaine, there was a tendency for reduced counts of acute pain avoidance behaviors over the entire 60-min period (59.49 ± 34.19 versus 87.27 ± 51.49, Table 3)

Summary

Introduction

Castration and tail-docking of lambs are common husbandry practices and are considered to be very painful for the animals [1,2]. Castration prevents mismating and allows males and females to live together [3]. It reduces aggressive behavior when the males reach sexual maturity and the aversive flavor of meat once animals are killed. Castration and tail docking are often carried out using a rubber ring, and pain relief must Code RRL NL RRB NB. Local anesthesia could provide some pain relief, but currently, access to these drugs requires a veterinary prescription. The process of injecting a local anesthetic into the tissues requires a reasonable level of skill to avoid self-injection. The use of multiple syringes and needles on the farm leads to environmental and safety concerns regarding the disposal of consumables and sharps

Methods

Results

Discussion

Conclusion