Topical anaesthesia reduces sensitivity of castration wounds in neonatal piglets

Abstract

The aim of this study was to do determine the efficacy of the topical anaesthetic Tri-Solfen® in the amelioration of the pain of castration in piglets. The trial was conducted over a three day period, and blocked across six litters with 12 piglets treated on days one and two, and 16 on day three. The piglets were randomly allocated by weight and litter to 1 of 4 treatment groups: (i) sham castration (SHAM; n = 10); (ii) surgical castration with no anaesthetic intervention (CAST; n = 10); (iii) surgical castration with post-operative topical anaesthesia (TRI; n = 10); (iv) surgical castration with a pre-operative intra-testicular lignocaine hydrochloride injection (LIG; n = 10). Wound sensitivity testing involved von Frey monofilaments of weights 4g and 300g, and an 18 gauge needle, used to stimulate the wound and surrounding skin respectively, at various pre-determined sites. Neonatal piglets receiving topical anaesthesia (Tri-Solfen®) spray into castration wounds had significantly lower wound sensitivity responses for up to 4h, compared to those castrated following intra-testicular lignocaine injection or those with no treatment. The use of topical anaesthetic is suggested as a practical and affordable method of improving piglet welfare during castration.

Electroencephalography Can Distinguish between Pain and Anaesthetic Intervention in Conscious Lambs Undergoing Castration

“…Following data collection, all animals were treated topically with 4.5 mL Tri-Solfen®topical anaesthetic (Bayer Animal Health, Pymble, NSW, Australia) by inserting the provided nozzle into the post-castration scrotal incision [23]. Lambs were also administered meloxicam subcutaneously at 1 mg/kg (Boehringer Ingelheim Pty Limited, North Ryde, NSW, Australia).…”

Innovative pain management solutions in animals may provide improved wound pain reduction during debridement in humans: An opinion informed by veterinary literature

“…Importantly, the application of the combination topical anaesthetic formulation delivered directly onto the wound peri‐operatively or immediately postoperatively was immediately recognised to have broader applications in livestock husbandry. Following extensive research trials involving many routine aversive husbandry procedures, Tri‐Solfen has now been demonstrated to be safe and efficacious in managing pain and improving healing of acute surgical wounds incurred during surgical castration and tail docking of lambs, surgical castration and dehorning of calves, and surgical castration of piglets . It is also proving effective in chronic wound conditions.…”

Optimal Methods of Documenting Analgesic Efficacy in Neonatal Piglets Undergoing Castration

“…Neural markers of pain mitigation, such as the expression of the c-fos gene and its protein product, Fos, in neurons of the spinal cord [75], are significantly reduced when piglets are castrated under effective local or general anaesthesia, as compared with piglets castrated without anaesthesia [43]. Furthermore, this is associated with a dramatic reduction in the nociceptive motor and vocal response to castration [31,32,74]. Additionally, reduced postoperative hyperalgesia has been documented in local anaesthetic-treated piglets [31,32].…”

“…Furthermore, this is associated with a dramatic reduction in the nociceptive motor and vocal response to castration [31,32,74]. Additionally, reduced postoperative hyperalgesia has been documented in local anaesthetic-treated piglets [31,32]. Together, these factors are considered to indicate that biomarkers of activation of the HPA axis, and inflammatory response lack specificity for pain mitigating effects of local and general anaesthetics, and are poor indicators of pain in piglets castrated under general or local anaesthesia [1].…”

“…Administered immediately following skin incision, the topical anesthetic formulation (containing 5% lidocaine, 0.5% bupivacaine, cetrimide and 1:2000 adrenalin), can act rapidly, within 30 seconds, to anaesthetise the wound and the exposed cordal tissues prior to severing the spermatic cords [31], which is considered the most painful part of the procedure. The longer acting local anaesthetic (bupivacaine), is included in the formulation, to assist provide extended post-operative sensory analgesia [32]. Extensive animal experimentation, such as to confirm safety and efficacy, is required for regulatory approval and authorization for use in piglets.…”