Local Anesthesia in Piglets Undergoing Castration—A Comparative Study to Investigate the Analgesic Effects of Four Local Anesthetics Based on Defensive Behavior and Side Effects

Abstract

The aim of the present study was to investigate the effect of four local anesthetics on pain relief during surgical castration under standardized conditions in conscious piglets. Therefore, 71 male piglets (three to seven days) were distributed into control groups (handling, castration without anesthesia or analgesia) and local anesthetic trial groups (procaine, lidocaine, bupivacaine, mepivacaine). Then, 20 min prior to castration, animals of the treatment groups, except piglets in the handling group, received an injection of a local anesthetic or sodium chloride of 0.5 mL intratesticularly and 0.5 mL subscrotally. During injection and castration, defensive behavior was evaluated. Locomotor activity, as well as postoperative bleeding, wound healing and average daily weight gain were assessed to detect side effects. The injection caused increased defensive movements, significantly in the bupivacaine group. Lidocaine and mepivacaine significantly reduced defensive movements during castration, and procaine and bupivacaine only during severing of the spermatic cord. Impairments of locomotor activity were found in piglets injected with lidocaine, bupivacaine or sodium chloride. Considering healing, bleeding and weight gain, no negative impacts were observed. In conclusion, lidocaine and mepivacaine were able to achieve significant pain relief during the castration procedure, whereas procaine and bupivacaine only during the severing of the spermatic cord. Moreover, the injection of bupivacaine seemed to be painful itself.

Impact of tearing spermatic cords during castration in live and dead piglets and consequences on welfare

“…Similar observations have been made after performing several procedures consecutively in piglets [23,25]. Our results confirm previous studies [10,11], indicating that particularly the kind of body movement can be considered a reliable indicator for the assessment of pain and distress during the castration of piglets, as it is able to determine differences between different castration techniques and pain treatments.…”

“…Therefore, it was not possible to numerically determine sound parameters such as entropy, energy or frequency and the generated data is not fully comparable to other study results. Similarly, Abendschön et al [11] applied a more practical approach by determining an acute onset of vocalization by human hearing. They, however, did not further categorize the perceived sounds.…”

“…In several studies, different approaches and software have been used to assess the effects of castration, different techniques, and pain treatment [6][7][8][9]. Movements during castration have been categorized according to their intensity and duration and were found to be suitable parameters for pain response evaluation [10,11]. Also vocalizations have frequently been used to assess pain and stress due to castration [5,8,10,12].…”

“…In these and other studies, researchers made different categorizations of sounds, for example they distinguished between lowfrequency and high-frequency calls with a threshold of 1000 Hz [6,13,14] or characterized vocalizations as 'grunts' (low energy), 'squeals' (higher energy) and 'screams' (highest energy) [15,16]. In a recent trial, vocalizations have been assessed without software in a more practical approach, but only an acute onset of increased vocalizations was evaluated and no further categorization has been made [11]. Detailed reviews on the subject have recently been published [17,18], where it was emphasized that there is no standardized procedure yet to assess the impact of castration and the efficacy of analgesic treatments.…”

Facile design of lidocaine-loaded polymeric hydrogel to persuade effects of local anesthesia drug delivery system: complete in vitro and in vivo toxicity analyses

“…Animals treated with COP-THB/LDC showed rapid onset of local anesthesia. After we confirmed that COP-THB/LDC has a longer retention time than COP-THB solution, we investigated the local anesthetic effect of COP-THB/LDC in vivo (Abendsch€ on et al, 2020). We used carrageenan (CGN)-induced inflammation on the RHP.…”