The effect of a topical anesthetic on the sensitivity of calf dehorning wounds

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J. Dairy Sci. 96:2894–2902 http://dx.doi.org/10.3168/jds.2012-5954 © American Dairy Science Association®, 2013. The effect of a topical anesthetic on the sensitivity of calf dehorning wounds C. Espinoza, S. Lomax, and P. Windsor1 Faculty of Veterinary Science, The University of Sydney, Private Bag 4003 Narellan, New South Wales 2567, Australia ABSTRACT Weary, 2000; Prayaga, 2007). Although the breeding of polled cattle can be viewed as the long-term solution to The objective was to determine the effect of a topical the problems associated with horned cattle, dehorning local anesthetic on the sensitivity of dehorning wounds will likely continue until all cattle are polled (Prayaga, in calves. Thirty 2-mo-old Holstein-Friesian calves were 2007). In the interim, it can be argued that the provi- randomly allocated to sham dehorning control (CON), sion of pain relief for these animals will enhance animal scoop dehorning without treatment with topical anes- welfare. thetic (SnoTA), or scoop dehorning with an application Several dehorning methods exist, including cautery, of a topical anesthetic (STA). Sensitivity was measured the use of caustic paste, and amputation. All of these by providing mechanical stimulation to the dehorned methods involve tissue damage and have been described wound and peri-wound area using von Frey monofila- as painful (Stafford and Mellor, 2005, 2011). Dehorning ments calibrated at 10 and 300 g. Calf responses were calves at an early age (before 2 mo) may help mitigate categorized as absent, minor, moderate, or severe. Sen- the pain and stress associated with the procedure. Re- sitivity measurements were performed before treatment moval of the horn before its attachment to the skull and at various time points up to 24 h posttreatment.

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measurements were performed before treatment moval of the horn before its attachment to the skull and at various time points up to 24 h posttreatment. (disbudding) tends to create a more superficial and Sham dehorned calves displayed unchanging absent or less traumatic wound, likely resulting in less pain and minor responses to stimulation. Regardless of whether bleeding and a shorter healing time (Petherick, 2011). topical anesthetic was applied, scoop dehorned calves Disbudding also allows for possibly less painful meth- were more likely to display minor, moderate, or severe ods to be used, including cautery and caustic disbud- responses than sham dehorned control calves, and re- ding (Stafford and Mellor, 2005). The Model Code of sponses tended to be most extreme at 4 h postdehorn- Practice for the Welfare of Animals: Cattle, however, ing. Calves in the STA group tended to be less likely to strongly advises against caustic disbudding (PISC, display minor, moderate, or severe responses than calves 2004). in the SnoTA group at most time points (exception at After horn-bud attachment to the skull (usually from 4 h postdehorning). Responses were significantly more about 2 mo of age), more invasive techniques such as likely to be less severe in STA calves than in SnoTA amputation dehorning are required (Anderson, 2009). calves at 40 min and 1.5 h following dehorning. Thus, Amputation dehorning has been found to induce abnor- the use of the topical anesthetic for calves reduced the mal behavior and affect physiological parameters that short-term sensitivity of scoop dehorning wounds. are likely to be indicative of pain (Stafford and Mel- Key words: dehorning, calf, pain, topical anesthesia lor, 2005). Amputation dehorning induces a significant increase in cortisol

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in (Stafford and Mel- Key words: dehorning, calf, pain, topical anesthesia lor, 2005). Amputation dehorning induces a significant increase in cortisol concentration that persists for 7 to INTRODUCTION 9 h (Sylvester et al., 1998a,b). Changes in animal be- havior, including increased frequency of head shaking, Dehorning is a painful yet important routine hus- ear flicking, tail flicking, and reduced rumination, are bandry procedure in the global dairy and beef indus- also suggestive of a painful experience that persists for tries. Dehorned cattle are safer to handle and cause up to 6 h following dehorning (Sylvester et al., 2004). fewer injuries to workers, other cattle, and farm animals Much research has been devoted to the use of pain (Stafford and Mellor, 2005). Cattle are also dehorned to relief for scoop dehorning pain (peri- and postproce- reduce bruising and hide damage, to minimize trough dure), with varying efficacy and duration of anesthesia space requirements, and to meet transport require- or analgesia. Different pain relief compounds have ments (Goonewardene and Hand, 1991; Faulkner and been investigated, including local anesthetics, analge- sics, and nonsteroidal antiinflammatory drugs. Scoop dehorning with the prior administration of lignocaine Received July 17, 2012. Accepted January 9, 2013. (local anesthetic) and ketoprofen (nonsteroidal antiin- 1 Corresponding author: peter.windsor@sydney.edu.au flammatory drug) has been found as one of the least 2894 DEHORNING AND TOPICAL ANESTHESIA 2895 painful methods to dehorn calves, with little change in mulesing pain in lambs. The formulation (Tri-Solfen, cortisol concentration detected and relatively normal Bayer Animal Health, Gordon, NSW, Australia) con- behavior observed after dehorning (McMeekan et al.,

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sol concentration detected and relatively normal Bayer Animal Health, Gordon, NSW, Australia) con- behavior observed after dehorning (McMeekan et al., tained short-acting (lignocaine) and long-acting (bu- 1998b, 1999). pivacaine) local anesthetics, adrenaline for hemostasis, Despite this knowledge, dehorning is commonly and cetrimide to prevent infection. The anesthetic had performed without pain relief because of the costs and the added benefit that it was easy to use and could be impracticalities associated with researched methods applied by the farmer. The aim of this experiment was (Petherick, 2005). Current options involve single or to assess the effect of the postoperative application of a multiple intramuscular, subcutaneous, or intravenous modified topical anesthetic formulation on the sensitiv- injections that must be administered by a veterinarian ity of scoop-dehorning wounds in dairy calves. some time before the dehorning procedure. This can be expensive and may involve double-handling of the MATERIALS AND METHODS animals, adding to the animal’s stress and the time required to perform the procedure. Thus, these regi- Animals and Housing mens are in opposition to the financial, labor, and time constraints imposed on commercial production. The experiment was approved by the Animal Eth- Despite these constraints, growing industry require- ics Committee of The University of Sydney and was ments for providing pain relief for calves undergoing de- conducted on 30 Holstein-Friesian heifer calves aged 8 horning must also be considered. The Council of Europe wk (±1 wk) at the Corstorphine Dairy Unit of The recommends the use of anesthesia for the dehorning of University of Sydney (New South Wales, Australia) in calves over 4 wk of age (Oliver, 2009). Pain control

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s the use of anesthesia for the dehorning of University of Sydney (New South Wales, Australia) in calves over 4 wk of age (Oliver, 2009). Pain control is autumn and spring 2010. Corstorphine operates as a also required for all calves under the Canadian Code commercial dairy that provides animals for research. of Practice for the Care and Handling of Dairy Cattle Calf weights were not able to be taken but were esti- (NFACC, 2009). Furthermore, the Australian Model mated at 45 to 55 kg. Calves close in age (2 mo ± 1 wk) Code of Practice for the Welfare of Animals: Cattle were preferred, thus only a small number of calves were recommends the use of local analgesics for dehorning suitable for experimentation on any certain day. The calves over 6 mo of age (PISC, 2004). Thus, the need to experiment was therefore replicated 3 times to obtain meet industry standards and the availability of suitable 10 animals in each of the 3 treatment groups. The dif- dehorning pain relief regimens for commercial produc- ferent experimental days (replicates 1, 2, and 3) were tion remain a challenge. considered blocks. On the each of the days of replicates Topical anesthesia may be a practical and more 1 and 2, 12 calves were available (n = 4 in each treat- affordable option for pain alleviation. Administered ment group) and on the day of replicate 3, 6 calves were postoperatively, local anesthetic agents are fast-acting available (n = 2 in each treatment group). The same and highly effective when applied to open wounds or protocol was followed on each experimental day. mucosal tissues (Bush, 2002; Lomax et al., 2008). The The calves were female replacement heifers raised preoperative injection of local anesthetics (cornual under commercial operational conditions. They were block; Weaver et

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le replacement heifers raised preoperative injection of local anesthetics (cornual under commercial operational conditions. They were block; Weaver et al., 2005) has been found to be effec- separated from their dams by 2 d of age and were there- tive in reducing pain (cortisol concentrations) for up after group-housed in 1-ha paddocks before and during to 2 h (lignocaine) (Petrie et al., 1996; Sylvester et al., the experimental period. Calves were fed a milk ration 1998b) and 4 h (bupivacaine) following dehorning (Mc- at 10% of their BW twice a day at 0730 and 1530 h via Meekan et al., 1998a). Cortisol concentrations increase an artificial teat and had ad libitum access to water thereafter, suggesting their effectiveness for acute (2–4 and kikuyu-based pasture. h) dehorning pain only. Local anesthesia combined with a nonsteroidal antiinflammatory drug (ketoprofen) has Experimental Design and Treatments been found to reduce the cortisol response to dehorning (McMeekan et al., 1998b; Sutherland et al., 2002). This On the day of experimentation, calves were moved suggests that local anesthetics, especially when used from their pens to an adjacent holding yard and then with other analgesics, can be effective in minimizing into a spinroll calf cradle (Arrow Farmquip, Tamworth, the pain and stress in the hours that follow disbudding NSW, Australia) in which treatments were imposed on or dehorning. The topical application of local anesthet- individual calves and data were collected. Calves were ics remains to be evaluated. placed into lateral recumbency (on right side) while in For the current experiment, a wound dressing was the cradle as per instruction from the manufacturer. formulated that was derived from a topical anes- Calves (total n = 30) were randomly assigned to

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the cradle as per instruction from the manufacturer. formulated that was derived from a topical anes- Calves (total n = 30) were randomly assigned to 1 of thetic formulation originally developed for the relief of 3 treatments: sham scoop dehorning (control group, Journal of Dairy Science Vol. 96 No. 5, 2013 2896 ESPINOZA ET AL. CON; n = 10), scoop dehorning without application of topical anesthetic (SnoTA; n = 10), and scoop dehorning with an immediate application of a topical anesthetic gel (Bayer Animal Health, Gordon, NSW, Australia) (STA; n = 10) Calves were sham-dehorned or dehorned between 0830 and 1100 h. Sham-dehorning was performed by manually manipulating and placing scoop dehorners over the horn bud but not incising. De- horning was performed by placing small scoop dehorners over the horn bud region and pulling apart the handles of the device to excise the horn bud and immediate sur- rounding skin. The STA calves received approximately 4 mL of topical anesthetic (TA) gel on each dehorning wound (total of 8 mL per calf), which was sufficient to cover the dehorning wound and cut skin edges. The gel was applied immediately after excision (within seconds) with a sterile, soft silicone-bristled brush. The TA had Figure 1. Sites subjected to light touch and pain stimulation sen- a thick, honey-like consistency that, once spread over sory testing: directly on the dehorned site (white stars) and adjacent the horn bud, had a thickness of approximately 2 to to dehorned site (black stars). 3 mm. The brush was cleaned between calves with a disinfectant solution. The TA was modified from its original formula (for of each calf to the stimulation of 4 sites directly on mulesing) with the intention that it would be more suit- the dehorned area (wound; left and right wounds)

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lf to the stimulation of 4 sites directly on mulesing) with the intention that it would be more suit- the dehorned area (wound; left and right wounds) and able for dehorning wounds. The TA used in this study 2 sites adjacent to each dehorned area (peri-wound; contained lignocaine (100.0 g/L, as the hydrochloride) Figure 1). The dehorning wound measured approxi- and bupivacaine (5.0 g/L, as the hydrochloride), mately 3 to 4 cm in diameter and chosen sites within adrenaline (100.0 mg/L, as tartrate), and cetrimide the wound were approximately 2 to 3 cm apart (hori- (5.0 g/L). The lignocaine concentration was doubled zontally and vertically). The peri-wound sites were 2 from the original formulation to produce a concen- cm from the dehorned wound edge. Four sites within trated gel more suitable for the smaller surface area of the wound were chosen to obtain an average indication the dehorning wound. The concentration of adrenaline of the whole wound sensitivity, which tends to have and the viscosity of the gel were also increased with changing bone and tissue composition with different in- the intention of encouraging increased hemostasis and nervation. Quantitative sensory testing was performed adherence of the TA to the wound, respectively. before dehorning on intact skin and was repeated at 1 and 40 min and 1.5, 4, and 24 h posttreatment. Assessment of Skin and Wound Sensitivity Evidence of local anesthesia, allodynia (pain from normally nonpainful stimuli), and primary and second- Quantitative sensory testing (QST) was performed ary hyperalgesia (increased pain sensation at the site of using calibrated von Frey monofilaments to assess the injury or distant from the site of injury, respectively) sensitivity of the dehorned wound and immediate ad- were assessed at each

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ments to assess the injury or distant from the site of injury, respectively) sensitivity of the dehorned wound and immediate ad- were assessed at each site using the von Frey mono- jacent area. von Frey monofilaments are instruments filaments. The head and rump responses of calves to that, depending on length and diameter, apply a specif- light-touch and pain stimulation were observed and ic calibrated force to a skin surface. Monofilaments that subjectively scored. A numerical rating scale was de- exerted 10 g (Bailey Instruments Ltd., Salford Quays, veloped to assess facial and head response based on UK) and 300 g (Touch Test, Stoelting Company, Wood similar work in lambs (Lomax et al., 2008), whereby Dale, IL) of force were used to apply repeatable light- 0 = no response; 1 = minor facial awareness such as touch and pain stimulation, respectively. The 10-g von an eye blink or widening or an ear flick; 2 = partial Frey was chosen because this force was successfully withdrawal reflex such as partial head rotation; and 3 used in previous lamb experiments (mulesing, castra- = full withdrawal reflex such as full head jerk or rota- tion, and tail-docking) to provide light-touch stimula- tion. Rump responses were graded as follows: 0 = no tion (Lomax et al., 2008, 2010). The 300-g von Frey response; 1 = minor involuntary motor response such was chosen because this force was successfully used in as local skin twitch, subcutaneous muscle twitch, or pilot experiments to elicit greater mechanical stimula- anal contraction; 2 = partial rump withdrawal reflex tion. Sensitivity was assessed by scoring the responses such as multiple subcutaneous muscle group contrac- Journal of Dairy Science Vol. 96 No. 5, 2013 DEHORNING AND TOPICAL ANESTHESIA 2897 tions, including anal

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s multiple subcutaneous muscle group contrac- Journal of Dairy Science Vol. 96 No. 5, 2013 DEHORNING AND TOPICAL ANESTHESIA 2897 tions, including anal contraction; and 3 = full rump or 3) to stimulation than SnoTA calves (P < 0.05). At withdrawal reflex. these time points, STA calves were 95 to 97% likely to show no response to stimulation compared with 85 to Statistical Analysis 89% in SnoTA calves. At 1 min and 24 h posttreatment, STA calves tended to be less likely to display more The aim was to evaluate the effect of treatment on severe responses than SnoTA calves (P > 0.05). At 4 response severity to QST. Given that the outcome h postdehorning, STA and SnoTA calves were likely to variable was both categorical (classed) and ordinal (in display similar responses to stimulation (P > 0.05). succession), with Y = 0, 1, 2, or 3 indicating increasing levels of pain severity, data were analyzed using ordinal von Frey and Area Effects logistic regression using ASReml 3.0 statistical software (Gilmour et al., 2009). The fixed effects of the model von Frey size had a significant effect on the severity were treatment, time (pretreatment, 1 and 40 min and of calf responses to stimulation (P < 0.001). Regardless 1.5, 4, and 24 h posttreatment) and their interaction, of treatment, calves were more likely to display higher von Frey monofilament size (10 or 300 g), area tested responses (Y = 1, 2, or 3) when stimulated with the (wound or peri-wound), observed area (head or rump), 300-g von Frey monofilament than when stimulated head side (left or right side), replicate (replicate 1, 2, by the 10-g von Frey monofilament (8 vs. 2% chance, or 3), and random effects were calf and time nested respectively; Table 1). within calf, to address clustering of the data. For all With

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s. 2% chance, or 3), and random effects were calf and time nested respectively; Table 1). within calf, to address clustering of the data. For all With stimulation of the wound using the 10-g von statistical calculations, P-values ≤0.05 were considered Frey monofilament, STA calves were more likely than statistically significant. SnoTA calves to show no response to stimulation at 1 and 40 min and 1.5 h postdehorning. At these time RESULTS points, SnoTA calves were 2, 4, and 3 times more likely, respectively, to show mild, moderate, or severe Overall responses than STA calves (Figure 3a). At 4 and 24 h postdehorning, probabilities between these 2 groups We observed a significant time and treatment inter- were similar. Although wound stimulation with the 300- action (P = 0.004) and significant effects of von Frey g von Frey monofilament was more likely to produce size (10 or 300 g; P < 0.001), area observed (head or more severe responses, stimulation produced similar rump; P < 0.001), side of head tested (left or right; P < 0.001) on the severity of calf responses to mechanical stimulation. No effect of area tested (wound or peri- wound; P = 0.076) or replicate (replicate 1, 2, or 3; P = 0.056) was observed. A high amount of between-calf variation was observed in responses. Time and Treatment Interaction The overall time and treatment interaction can be observed in Figure 2. Before treatment, all calves were 98% likely to display no response (Y = 0) to stimula- tion. Thereafter, CON calves remained highly likely (98–99%) to show no response to stimulation at all time points following sham-dehorning. Dehorned calves, re- gardless of treatment with or without topical anesthetic (SnoTA and STA calves), tended to show an increase in response severity over time, with

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, re- gardless of treatment with or without topical anesthetic (SnoTA and STA calves), tended to show an increase in response severity over time, with calves being more likely to show a minor, moderate, or severe response (Y = 1, 2, or 3) after dehorning than before dehorning. Figure 2. Probability of calves in each treatment group displaying responses (Y; 0 = no response, 1 = minor, 2 = moderate, 3 = severe) Calves in the STA group tended to be less likely to at different time points. Results combine the effect of 10-g and 300- display more severe responses than SnoTA calves at g von Frey monofilaments and wound and peri-wound areas (CON most time points after dehorning. = sham dehorned; SnoTA = scoop dehorned and no treatment with topical anesthetic; STA = scoop dehorned and treated with topical At 40 min and 1.5 h postdehorning, STA calves were anesthetic). a–cWithin each time point, treatment groups not sharing a less likely to display more severe responses (Y = 1, 2, common letter are significantly different (P < 0.05). Journal of Dairy Science Vol. 96 No. 5, 2013 2898 ESPINOZA ET AL. Table 1. The overall effect of von Frey monofilament size (10 or 300 g), observation area (head or rump), and side of the head tested (left or right) on the probability of calves displaying zero, minor, moderate, and severe responses to mechanical stimulation (Y = 0, 1, 2, and 3, respectively) Response Item Y=0 Y=1 Y=2 Y=3 P-value von Frey size <0.001 10 g 0.9845 0.0138 0.0011 0.0006 300 g 0.9248 0.0663 0.0059 0.0030 Observation area <0.001 Head 0.9424 0.0509 0.0044 0.0023 Rump 0.9795 0.0182 0.0015 0.0008 Head side <0.001 Left 0.9603 0.0351 0.0031 0.0015 Right 0.9700 0.0266 0.0023 0.0011 proportions of likelihoods as the 10-g von Frey wound stimulation (P < 0.001), with calves

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9603 0.0351 0.0031 0.0015 Right 0.9700 0.0266 0.0023 0.0011 proportions of likelihoods as the 10-g von Frey wound stimulation (P < 0.001), with calves tending to display stimulation (Figure 3b). more severe responses when stimulated on the left com- Stimulation of the peri-wound tissue tended to pro- pared with the right side of the head (Table 1). duce similar or slightly less severe responses than direct We observed benefits from the more viscous and stimulation of the wound site, although this difference concentrated formulation compared with the original was not significant (P = 0.076). Stimulation of this area aqueous TA. In contrast to the original formula, the with the 10-g von Frey resulted in a 98, 95, 93, 94, and new TA was able to be effectively applied onto the 95% chance of SnoTA calves showing no response (Y dehorning wound and adhered well immediately after = 0) at 1 and 40 min and 1.5, 4, and 24 h, respectively application. The TA was able to momentarily delay, (Figure 4a). The STA calves were slightly more likely but not stop, bleeding from the wound, and adherence to show no response at 1 and 40 min and 1.5 and 24 diminished once arterial bleeding commenced. Adher- h postdehorning (99, 99, 98, and 97%, respectively). ence of the TA to the adjacent intact skin was observed At 1 and 40 min and 1.5 h, STA calves were between 24 h postapplication. 2 and 4 times less likely than SnoTA calves to display mild, moderate, or severe responses. At 4 h posttreat- DISCUSSION ment, STA and SnoTA calves showed similar response probabilities, with calves from both treatments being The immediate treatment of wounds with a TA approximately 93 and 94% likely to show no response following scoop dehorning was able to reduce wound to stimulation (respectively). Stimulation

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a TA approximately 93 and 94% likely to show no response following scoop dehorning was able to reduce wound to stimulation (respectively). Stimulation of the peri- sensitivity for up to 1.5 h after application. This find- wound area with the 300-g von Frey produced more ing suggests that the application of topical anesthesia severe responses in SnoTA than STA calves, except can provide some anesthetic effect, albeit short-term, at 4 h posttreatment, when the responses were equal thus likely reducing the postoperative acute pain from (Figure 4b). At 1 and 40 min and 1.5 h postdehorn- scoop dehorning in 2-mo-old dairy calves. The present ing, STA calves were between 2 and 4 times less likely experiment also provides new information on the extent than SnoTA calves to show more severe responses (Y and progression of the sensitivity of dehorned wounds, = 1, 2, or 3). At 24 h postdehorning, STA calves were and the effect of topical anesthesia, as assessed through more likely to not respond (Y = 0) to stimulation than QST. SnoTA calves (86 vs. 80%, respectively). Local anesthetics act directly on nervous tissue to block the conduction of nerve impulses (Flecknell, Observation Area Effect 1996). Research into the use of local anesthesia for alle- viating dehorning pain has been extensive and indicates The severity of responses differed significantly be- that preoperative administration of the local anesthetic tween stimulation of the head compared with the rump lignocaine (cornual block; Weaver et al., 2005) is able to area (P < 0.001). Overall, regardless of treatment, largely eliminate the cortisol response during the first head responses tended to be more severe than rump 2 h after amputation dehorning (Petrie et al., 1996; responses (Table 1). Sylvester et al., 1998b). The

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d responses tended to be more severe than rump 2 h after amputation dehorning (Petrie et al., 1996; responses (Table 1). Sylvester et al., 1998b). The TA formulation developed for use in the present experiment was derived from a Head Side Effect commercially available topical anesthetic (Tri-Solfen, We found a significant difference comparing each side Bayer Animal Health) and contained lignocaine and of the head tested on the response severity of calves to bupivacaine. Both are local anesthetic agents that pro- Journal of Dairy Science Vol. 96 No. 5, 2013 DEHORNING AND TOPICAL ANESTHESIA 2899 Figure 3. Probability of calves in each treatment group displaying responses (Y; 0 = no response, 1 = minor response, 2 = moderate re- Figure 4. Probability of calves in each treatment group displaying sponse, 3 = severe response) upon stimulation of the wound with 10-g responses (Y; 0 = no response, 1 = minor response, 2 = moderate re- (a) and 300-g (b) von Frey monofilaments (CON = sham dehorned; sponse, 3 = severe response) upon stimulation of the peri-wound area SnoTA = scoop dehorned and no treatment with topical anesthetic; with 10-g (a) and 300-g (b) von Frey monofilaments (CON = sham STA = scoop dehorned and treated with topical anesthetic). dehorned; SnoTA = scoop dehorned and no treatment with topical an- esthetic; STA = scoop dehorned and treated with topical anesthetic). vide intermediate (1–2 h) and long-acting (3–7 h) relief from pain, respectively (AHFS, 2012). The formulation mulesing in lambs, for which the original formulation also contained adrenalin, which causes vasoconstriction, was developed. From our observations, the new formu- promotes hemostasis, and slows the systemic absorp- lation achieved greater adherence to the wound and tion of local

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our observations, the new formu- promotes hemostasis, and slows the systemic absorp- lation achieved greater adherence to the wound and tion of local anesthetics, helping to prolong their effect peri-wound area than did the original formulation. This on tissues (Lomax et al., 2008). The local anesthetics was likely due to the higher viscosity of the new TA and adrenalin, as combined in the experimental TA compared with the more aqueous original formulation. gel, were present in concentrations similar to those pro- It is important to note that this adherence to the wound viding effective anesthesia and hemostasis in humans appeared to diminish with arterial bleeding, suggesting and lambs, while still below toxic thresholds for lambs that the increased concentration of adrenalin in the (Bush, 2002; Lomax et al., 2008). new formulation was ineffective at combating heavy The formulation used in this experiment was devel- blood flow. oped specifically for use on scoop-dehorning wounds in von Frey monofilaments provide a specific, calibrated calves. The small wound size and mucosal surface area force to a skin surface. These filaments are advanta- and the potential high blood loss from arterial bleed- geous for pain assessment as they can easily be used to ing associated with scoop dehorning presented different provide repeatable mechanical stimulation to a subject challenges compared with the wounds resulting from to gauge skin or wound surface sensitivity and its pro- Journal of Dairy Science Vol. 96 No. 5, 2013 2900 ESPINOZA ET AL. gression over time. Thus, QST with von Frey monofila- calves, suggesting an intermediate effect and rapid on- ments was chosen to assess the efficacy of the TA as this set of anesthesia. approach was believed to provide a good indication of

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ffect and rapid on- ments was chosen to assess the efficacy of the TA as this set of anesthesia. approach was believed to provide a good indication of Similar sensitivity between SnoTA and STA calves the extent and progression of local anesthesia and pain at 4 h may signify waning efficacy of bupivacaine in sensitivity over time. Although cortisol concentration is the formulation. At 4 h, the lower sensitivity in STA, commonly used as a measure of pain, the hormone only compared with SnoTA calves, that was observed at provides a relative indication of the overall noxiousness most time points was not observed. This result was or stress of an experience. Nonpainful external stress- unexpected given that i.v. administration of bupiva- ors, including handling, restraint, and the presence of caine is generally thought to last 3 to 7 h (AHFS, 2012) dogs or humans, can also cause cortisol concentrations and 4 h after scoop dehorning in 3- to 4-mo-old calves to increase (Kilgour and de Langen, 1970; Mears et al., (McMeekan et al., 1998a,b). In addition, the inclusion 1999). In addition, cortisol concentrations have been of adrenaline prolongs the activity of local anesthetics shown to increase even in the absence of pain, such by slowing absorption into the bloodstream at the site as during surgical procedures under general anesthe- of application. However, little documentation exists on sia, as cortisol plays an important role in maintaining the topical application of bupivacaine (and lignocaine) blood volume (Fox et al., 1994; Hughan et al., 2001). in calves. Research investigating the use of topical Furthermore, although the quantification of behavioral anesthesia to provide anesthesia for mulesed lambs re- response is a validated measure of pain in calves, some ported

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the quantification of behavioral anesthesia to provide anesthesia for mulesed lambs re- response is a validated measure of pain in calves, some ported efficacy for up to 8 h posttreatment (Lomax et behaviors associated with (scoop) dehorning, such as al., 2008). In the present experiment, the pain sensitiv- ear flicking and head shaking, may occur due to the ity at 4 h may have been affected by the diminished irritation of flies or blood loss, rather than to pain per adherence of the TA observed once heavy bleeding se (Stafford and Mellor, 2006). von Frey monofilaments commenced, which led to reduced efficacy of the local have been used in previous studies to assess different anesthetics. Effective and lasting TA to wound contact analgesic interventions in humans and animals (Bren- is important for the absorption and efficacy of topical nan et al., 1996; Keizer et al., 2007; Lomax et al., 2008). local anesthesia. Responses at 4 h may also have been In the present study, von Frey monofilaments were used affected by calf hunger or agitation, as this time point for the first time to gauge the sensitivity and anesthesia was the fourth and final of the day and close to feeding of dehorning wounds with and without the application time. The high between-calf variation in response to of a TA. The results indicate an increase in the sensi- stimulation may also have contributed to the varied tivity of the dehorned wound site and adjacent area, responses at this time point. regardless of treatment with or without the TA, which The onset of anesthesia from the TA is relatively persisted at higher levels compared with the control uncertain, with a reduction in sensitivity observed 1 animals, for up to 24 h postdehorning. min following application, although this was not sta- Light

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certain, with a reduction in sensitivity observed 1 animals, for up to 24 h postdehorning. min following application, although this was not sta- Light touch stimulation of the wound and peri-wound tistically significant. Inference from other studies on area showed an increase in allodynia in scoop dehorned the topical application of local anesthetics for the relief calves. Regardless of treatment with or without TA, of surgical pain from husbandry procedures in lambs dehorned calves showed an increased likelihood of dis- and calves suggests that the onset of anesthesia may playing more vigorous reflex responses than calves that occur between 1 and 3 min postapplication (Lomax et were sham-dehorned. This suggests the presence of, al., 2008, 2010). Although not directly comparable, the and increase in, allodynia of damaged tissues over time. onset of anesthesia from the preoperative administra- Similarly, more painful stimulation of these sites (with tion of lignocaine (cornual block; Weaver et al., 2005) the 300-g von Frey monofilament) showed increasing for dehorning is approximately 3 to 5 min. Thus, TA primary and secondary hyperalgesia, which peaked 4 h probably has a more rapid onset as agents are rapidly postdehorning. absorbed from the exposed mucosa. Application of TA demonstrated that a significant Other factors found to affect the severity of response reduction in sensitivity could be achieved. The TA sig- to QST included the part of the body observed (head nificantly reduced wound sensitivity at 40 min and 1.5 vs. rump) and side of the head tested (left vs. right). h postdehorning in treated calves. This demonstrated Calves tended to display more severe head than rump that lignocaine and bupivacaine were effectively ab- responses, which may be due to

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s demonstrated Calves tended to display more severe head than rump that lignocaine and bupivacaine were effectively ab- responses, which may be due to increased avoidance sorbed from the dehorning wound, resulting in local closer to the site of stimulation or to restriction of calf anesthesia. Furthermore, at 1 min postdehorning, STA body movement in the calf crush. Given that the calves calves, although not significantly different compared were placed in lateral recumbency on the right side with SnoTA calves, were also not different from CON may explain why calves tended to display more severe Journal of Dairy Science Vol. 96 No. 5, 2013 DEHORNING AND TOPICAL ANESTHESIA 2901 responses when the left side of the horn and peri-wound ments, Peter Thomson for statistical help, and Craig were stimulated; the calf’s head had restricted move- Kristo and the staff from the Corstophine Dairy Unit ment to the right sight side, thus limiting the response for technical assistance. vigor of the calf’s head to that side. No significant difference in sensitivity was observed REFERENCES between the dehorned wound site and the undamaged adjacent area. This may be due to the bony nature ASHP (American Society of Health-System Pharmacists). 2012. AHFS Drug Information. ASHP, Bethesda, MD. of the dehorned wound in 2-mo-old Holstein Friesian Anderson, N. 2009. Dehorning of Calves. Factsheet. Ministry of Agri- calves, which are likely to have little to no innervation culture, Food and Rural Affairs, Guelph, Ontario, Canada. or sensory tissue to respond to stimulation. The use Brennan, T. J., E. P. Vandermeulan, and G. F. Gebhart. 1996. Char- acterization of a rat model of incisional pain. Pain 64:493–501. of algometry to determine the mechanical nociceptive Bush, S. 2002. Is cocaine

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Char- acterization of a rat model of incisional pain. Pain 64:493–501. of algometry to determine the mechanical nociceptive Bush, S. 2002. Is cocaine needed in topical anaesthesia? Emerg. Med. threshold may provide a clearer indication of sensitiv- J. 19:418–422. ity at these 2 sites and will likely help address the low Faulkner, P. M., and D. Weary. 2000. Reducing pain after dehorning in dairy calves. J. Dairy Sci. 83:2037–2041. responsiveness of the calves to von Frey stimulation. Flecknell, P. A. 1996. Laboratory Animal Anaesthesia: A Practical Heinrich et al. (2010) successfully used pressure algom- Introduction for Research Workers and Technicians. 2nd ed. Aca- etry to gauge the mechanical nociceptive threshold of demic Press, London, UK. Fox, S. M., D. J. Mellor, E. C. Firth, H. Hodge, and C. R. Lawoko. calves undergoing dehorning with local anesthesia with 1994. Changes in plasma cortisol concentrations before, during and or without a nonsteroidal antiinflammatory drug. Fur- after analgesia, anaesthesia and anaesthesia plus ovariohysterec- thermore, this experiment could be further improved tomy in bitches. Res. Vet. Sci. 57:110–118. Gilmour, A., B. Gogel, B. Cullis, and R. Thompson. 2009. ASReml by assessing sensitivity of the incised skin edge of the User Guide. Release 3.0 ed. VSN International Ltd., Hemel Hemp- wound, which Lomax et al. (2008) found to be highly stead, UK. sensitive in mulesed lambs. Goonewardene, L., and R. Hand. 1991. Studies on dehorning steers in Alberta feedlots. Can. J. Anim. Sci. 71:1249–1252. Local anesthetics generally have poor skin permeabil- Heinrich, A., T. F. Duffield, K. D. Lissemore, and S. T. Millman. 2010. ity, which limits their use for effective preprocedural The effect of meloxicam on behaviour and pain

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field, K. D. Lissemore, and S. T. Millman. 2010. ity, which limits their use for effective preprocedural The effect of meloxicam on behaviour and pain sensitivity of dairy skin anesthesia (Lomax et al., 2008). However, the calves following dehorning with a local anaesthetic. J. Dairy Sci. 93:2450–2457. benefit in the postprocedural application of local anes- Hughan, S. C., J. M. Loose, D. J. Caddy, B. J. Canny, A. J. Tilbrook, thetics lies in the rapidity and efficacy when they are and I. R. Young. 2001. Combined xylazine and ketamine as an applied directly to open wounds (Bush, 2002; Lomax analgesic regimen in sheep. Aust. Vet. J. 79:207–211. Keizer, D., M. van Wijhe, W. J. Post, D. R. A. Uges, and J. M. K. H. et al., 2008). Pain relief for dehorning could be further Wierda. 2007. Assessment of the clinical relevance of quantitative enhanced by developing and including a long-acting sensory testing with Von Frey monofilaments in patients with al- analgesic for a more holistic pain management regimen. lodynia and neuropathic pain. A pilot study. Eur. J. Anaesthesiol. 24:658–663. Kilgour, R., and H. de Langen. 1970. Stress in sheep resulting from CONCLUSIONS management practices. Pages 65–76 in Proc. New Zealand Soc. Anim. Prod. Vol. 30. New Zealand Soc. Anim. Prod. Lomax, S., H. Dickson, M. Shiel, and P. A. Windsor. 2010. Topical A postoperative topical anesthetic applied to scoop anaesthesia alleviates short-term pain of castration and tail dock- dehorned 2-mo-old dairy calves was able to provide ing in lambs. Aust. Vet. J. 88:67–74. short-term wound anesthesia, and thus has the po- Lomax, S., M. Sheil, and P. A. Windsor. 2008. Impact of topical an- aesthesia on pain alleviation and wound healing in lambs after tential to significantly reduce postoperative

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. A. Windsor. 2008. Impact of topical an- aesthesia on pain alleviation and wound healing in lambs after tential to significantly reduce postoperative pain as- mulesing. Aust. Vet. J. 86:159–168. sociated with scoop dehorning. The incorporation of McMeekan, C. M., D. J. Mellor, K. J. Stafford, R. A. Bruce, R. N. effective and practical pain relief to address the pain Ward, and N. G. Gregory. 1998a. Effects of local anaesthesia of 4 to 8 hours’ duration on the acute cortisol response to scoop de- of the procedure and long-term pain could further en- horning in calves. Aust. Vet. J. 76:281–285. hance the welfare of calves undergoing this procedure McMeekan, C. M., K. J. Stafford, D. J. Mellor, R. A. Bruce, R. N. and facilitate the adoption of a pain relief regimen into Ward, and N. G. Gregory. 1998b. Effects of regional analgesia and/ or a non-steroidal anti-inflammatory analgesic on the acute cor- commercial dairy production. tisol response to dehorning in calves. Res. Vet. Sci. 64:147–150. McMeekan, C. M., K. J. Stafford, D. J. Mellor, R. A. Bruce, R. N. Ward, and N. G. Gregory. 1999. Effects of a local anaesthetic and ACKNOWLEDGMENTS a nonsteroidal anti-inflammatory analgesic on the behavioural re- sponses of calves to dehorning. N. Z. Vet. J. 47:92–96. The authors thank the Australian Research Council Mears, G. J., F. A. Brown, and L. R. Redmond. 1999. Effects of han- (Majura Park, ACT, Australia), Animal Ethics Pty dling, shearing and previous exposure to shearing on cortisol and beta-endorphin responses in ewes. Can. J. Anim. Sci. 79:35–38. Ltd. (Yarra Glen, VIC, Australia), and Bayer Animal NFACC. 2009. Code of Practice for the Care and Handling of Dairy Health (Pymble, NSW, Australia) for funding this Cattle. National Farm Animal Care Council,

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2009. Code of Practice for the Care and Handling of Dairy Health (Pymble, NSW, Australia) for funding this Cattle. National Farm Animal Care Council, Lacombe, Alberta, project. We are grateful to Meredith Sheil and the fol- Canada. Oliver, M. A. 2009. Alternatives to Castration and Dehorning—Final lowing staff from The University of Sydney, Faculty of Report. Institut de Recerca i Tecnologia Agroalimentàries (IRTA), Veterinary Science: Greg Cronin for advice and com- Barcelona, Spain. Journal of Dairy Science Vol. 96 No. 5, 2013 2902 ESPINOZA ET AL. Petherick, J. C. 2005. Animal welfare issues associated with extensive Stafford, K. J., and D. J. Mellor. 2011. Addressing the pain associated livestock production: The northern Australian beef cattle industry. with disbudding and dehorning in calves. Appl. Anim. Behav. Sci. Appl. Anim. Behav. Sci. 92:211–234. 135:226–231. Petherick, J. C. 2011. The animal welfare impacts of dehorning cattle. Sutherland, M. A., D. J. Mellor, K. J. Stafford, N. G. Gregory, R. A. Aust. Cattle Vet. 60:24–25. Bruce, and R. N. Ward. 2002. Cortisol responses to dehorning of Petrie, N. J., D. J. Mellor, K. J. Stafford, R. A. Bruce, and R. N. calves given a 5-h local anaesthetic regimen plus phenylbutazone, Ward. 1996. Cortisol responses of calves to two methods of disbud- ketoprofen, or adrenocorticotropic hormone prior to dehorning. ding used with or without local anaesthesia. N. Z. Vet. J. 44:9–14. Res. Vet. Sci. 73:115–123. PISC (Primary Industries Standing Committee). 2004. Model Code of Sylvester, S. P., K. J. Stafford, D. J. Mellor, R. A. Bruce, and R. N. Practice for the Welfare of Animals: Cattle. 2nd ed. Primary In- Ward. 1998a. Acute cortisol responses of calves to four methods of dustries Standing Committee, CSIRO

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Welfare of Animals: Cattle. 2nd ed. Primary In- Ward. 1998a. Acute cortisol responses of calves to four methods of dustries Standing Committee, CSIRO Publications, Collingwood, dehorning by amputation. Aust. Vet. J. 76:123–126. Victoria, Australia. Sylvester, S. P., K. J. Stafford, D. J. Mellor, R. A. Bruce, and R. N. Prayaga, K. C. 2007. Genetic options to replace dehorning in beef Ward. 1998b. Acute cortisol responses of calves to scoop dehorning cattle—A review. Aust. J. Agric. Res. 58:1–8. with prior use of local anaesthetic and/or cautery of the wound. Stafford, K. J., and D. J. Mellor. 2005. Dehorning and disbudding Aust. Vet. J. 76:118–122. distress and its alleviation in calves. Vet. J. 169:337–349. Sylvester, S. P., K. J. Stafford, D. J. Mellor, R. A. Bruce, and R. N. Stafford, K. J., and D. J. Mellor. 2006. The assessment of pain in Ward. 2004. Behavioural responses of calves to amputation dehorn- cattle: A review. Pages 1–10 in CAB Reviews: Perspectives in Ag- ing with and without local anaesthesia. Aust. Vet. J. 82:697–700. riculture, Veterinary Science, Nutrition and Natural Resources. Weaver, D. A., G. S. Jean, and A. Steiner. 2005. Bovine Surgery and CAB International, Wallingford, UK. Lameness. 2nd ed. Blackwell Publishing Ltd., Oxford, UK. Journal of Dairy Science Vol. 96 No. 5, 2013