Duration of action of a topical anaesthetic formulation for pain management of mulesing in sheep

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bs_bs_banner PRODUCTION ANIMALS Duration of action of a topical anaesthetic formulation for pain management of mulesing in sheep PRODUCTION ANIMALS S Lomax,a* M Sheilb and PA Windsora Breech strike involving infestation of the ‘crutch’ or perineal region is Objective To investigate the effect of topical anaesthesia on the most common form of blowfly strike, occurring to some degree in ‘mothering up’ of lambs after mulesing and marking, and for pain almost every susceptible flock each year in Australia.1–4 alleviation over a 24-h period. Design Two separate trials were performed on Merino lambs The mules procedure, developed in the 1930s, involves the removal of undergoing the mules procedure for flystrike prevention, to the folds of skin from the breech area of sheep in order to decrease assess the efficacy of immediate postoperative topical anaesthetic susceptibility to oviposition by L. cuprina through reduced moisture wound dressing containing lignocaine (hydrochloride) 40.6 g/L, and faeces retention. It is widely accepted as the most effective method bupivacaine (hydrochloride) 4.5 g/L, adrenaline (tartrate) 24.8 mg/L for the lifetime prevention of breech strike.5 and cetrimide 5.0 g/L in a gel base (Bayer Animal Health, Gordon, NSW, Australia). Despite the preventive health benefits, there has been growing concern regarding the welfare impact of the procedure itself. In the Methods In both trials, lambs were assigned to one of three treat- past, the procedure was undertaken without analgesia, resulting in ment regimens: control, mules procedure with topical anaesthetic evidence of acute pain and stress.6–9 The Australian Wool Industry has (0.5 mL/kg) and mules procedure without topical anaesthetic treat- faced increasing pressure in recent years

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ress.6–9 The Australian Wool Industry has (0.5 mL/kg) and mules procedure without topical anaesthetic treat- faced increasing pressure in recent years to develop alternative, more ment. Parameters measured included body weight, assessment of humane methods of flystrike prevention to support a phase-out of the skin and wound sensitivity to light touch and pain stimulation, mules procedure. The ultimate solution is believed to lie in breeding behavioural responses and time to mother up and to feed. sheep resistant to breech strike (such that mulesing is no longer Results In both trials there was rapid (1 min) and prolonged (up required). Intensive genetic research and breeding programmes are to 24 h) wound analgesia as shown by lower scores for light touch underway, but this is a long-term objective.10–12 Additional research is (P < 0.001) and pain responses (P < 0.001), with absent or signifi- targeting the more immediate goal of developing more humane prac- cantly diminished primary and secondary hyperalgesia (P ⱕ 0.05) tices to deal with breech wrinkle. and significant reduction in pain-related behaviours (P < 0.001) in treated versus untreated lambs. In 2005 in Australia, a multifunction topical anaesthetic, antiseptic and haemostatic wound dressing (Tri-Solfen®, Bayer Animal Health, Conclusion Significant pain alleviation and improved recovery Gordon, NSW, Australia) became available for use on permit through can be achieved in lambs for at least 24 h after mulesing through the use of topical anaesthesia. It is suggested that the haemostatic veterinarians for immediate post-procedural application to mulesing action of adrenalin, together with inhibition of the inflammatory wounds in sheep. Tri-Solfen® is a spray-on topical anaesthetic, hae- cascade and

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sing action of adrenalin, together with inhibition of the inflammatory wounds in sheep. Tri-Solfen® is a spray-on topical anaesthetic, hae- cascade and the barrier effect of the gel within the product, may mostatic and antiseptic gel agent consisting of lignocaine (40.6 g/L), explain the prolonged anaesthesia up to 24 h observed in the bupivacaine (4.5 g/L), adrenalin (24.8 mg/L) and cetrimide (5.0 g/L). present study. These results suggest that topical anaesthesia has We have been examining the efficacy of this form of treatment to both the capacity to dramatically improve the welfare of lambs under- alleviate pain and enhance wound healing and recovery in the first 8 h going mulesing. after the procedure. Our studies indicate that significant wound desensitisation, improved lamb recovery rates and enhanced wound Keywords allodynia; flystrike; hyperalgesia; mulesing; sheep; von healing can be achieved.13 Frey monofilament Observations during our studies, together with anecdotal reports of Abbreviations HI, hot iron; LT, light touch; NRS, numerical rating improved lamb behaviour up to 24 h post-mulesing, led us to hypoth- scale; NSAID, non-steroidal antiinflammatory drug esise that treatment with the topical anaesthetic product may effect a Aust Vet J 2013;91:160–167 doi: 10.1111/avj.12031 prolonged analgesic response because of inhibition of the pain esca- lation response. F lystrike is one of the most significant health and welfare con- The mother–lamb bond is important to lamb survival early in life cerns for the Australian and New Zealand sheep industries. It is and it can be disrupted by human interventions, particularly in a disease resulting from the infestation of living tissue by fly Merino ewes, which have the reputation of being poor

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an interventions, particularly in a disease resulting from the infestation of living tissue by fly Merino ewes, which have the reputation of being poor mothers.14 larvae, initiated by oviposition by the sheep blowfly Lucilia cuprina. In commercial farm situations, lambs are returned immediately to pasture with their mothers following husbandry procedures such as *Corresponding author. mulesing. This process is referred to as ‘mothering up’ and is impor- a Faculty of Veterinary Science, University of Sydney, PMB 3, Camden, New South Wales 2570, Australia; sabrina.lomax@sydney.edu.au tant for improved lamb recovery because the first feed of milk leads to b Animal Ethics Pty Ltd, Yarra Glen, Victoria, Australia a rise in endorphins, which can ameliorate acute pain. Additionally, © 2013 The Authors 160 Australian Veterinary Journal Volume 91, No 4, April 2013 Australian Veterinary Journal © 2013 Australian Veterinary Association PRODUCTION ANIMALS lambs that have a delay in the time to mother up are more susceptible dams for 4 h. They were then selected at random, weighed and spray- to exposure, including hypothermia and dehydration, which can lead marked numerically and placed in marking cradles. Preoperative to morbidity and in some cases mortality.14 There are no discrete data PRODUCTION ANIMALS skin sensitivity to light touch (LT) and pain stimulation was recorded in the literature describing the effects of mulesing on the time to (see later). Mulesing was performed using a standard ‘V’-modified mother up and feed in lambs, despite the painful nature of the proce- technique. In Trial 1, the HI tail docking was performed using a gas dure. This information has the potential to provide us with a simple tail-docking knife that had been preheated to the

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cking was performed using a gas dure. This information has the potential to provide us with a simple tail-docking knife that had been preheated to the correct temperature tool to assess lamb discomfort and determine the efficacy of pain to efficiently seal the coccygeal blood vessels. The skin of the tail was management regimens for improving lamb recovery post-mulesing. pushed towards the lamb’s body to locate the correct position between coccygeal vertebrae 2 and 3 and the tail elevated to avoid burning of In the present study, we examined the effect of mulesing on mothering the perineum. The lever of the knife was squeezed and after 2 s the tail up of lambs following mulesing and marking, and the duration of was removed. In lambs assigned to treatment group 2, Tri-Solfen® was efficacy of a topical anaesthetic for improving lamb recovery and applied directly to the mulesing and tail-docking wounds using a alleviating pain over a 24-h period. metered dose applicator (6–12 mL, based on lamb weight) immedi- ately after the procedure(s). Postoperative skin and wound sensitivity Materials and methods testing was repeated at 1 min post-procedure. Lambs were returned to their dams in a 6 ¥ 4 m pen, where the time taken for lambs to find Two trials were performed on 6–8-week-old Merino lambs from a their dams and feed was recorded. The ewes and lambs were then commercial flock in the Southern Highlands, New South Wales, Aus- moved to one of three pasture-covered holding yards (20 ¥ 10 m) tralia. All animal procedures were conducted with prior institutional in mixed treatment groups and left undisturbed for 24 h. At 1 h and animal ethics approval in accordance with the National Health and 24 h post-mulesing, the behavioural response scores were recorded Medical

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At 1 h and animal ethics approval in accordance with the National Health and 24 h post-mulesing, the behavioural response scores were recorded Medical Research Council’s Code of Practice for the Care and Use of (Trial 1) as described later. At 24 h after the behavioural assessment Animals for Scientific Purposes. The trials were conducted in July 2008 (Trial 1), lambs were then re-drafted, weighed and skin and wound (Trial 1; n = 23) on lambs undergoing both mulesing and hot-iron sensitivity testing was repeated. (HI) tail docking and in January 2009 (Trial 2; n = 42) on lambs undergoing mulesing only (previously tail docked). The mean initial Body weights body weight of lambs in Trial 1 was 11.89 ⫾ 0.3 kg and for lambs in Weights were recorded using digital scales (Rudweigh®, Gallagher Trial 2 it was 21.04 ⫾ 0.5 kg. In both trials, lambs were assigned to one Animal Management Systems, Australia), which were calibrated and of the following treatment regimens, randomised within each trial zeroed prior to each measurement and accurate to 0.1 kg. (Table 1): (1) control, in which lambs were handled but remained unmulesed (or tail docked in Trial 1); (2) mulesing (and HI tail Assessment of skin and wound sensitivity to light touch and docking in Trial 1) with immediate postoperative topical anaesthetic pain stimulation wound dressing (6–12 mL of Tri-Solfen® sprayed onto wound); (3) Skin and wound sensitivity was assessed at five predetermined sites on mulesing (with HI tail docking in Trial 1) without topical anaesthetic the skin surrounding the mulesing wound and nine sites within the dressing; and (4) HI tail docking only (Trial 1, behavioural observa- mulesing wound before and then 1 min and 24 h after mulesing using tions as described later). weighted von

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docking only (Trial 1, behavioural observa- mulesing wound before and then 1 min and 24 h after mulesing using tions as described later). weighted von Frey monofilaments, which are calibrated to bend at predetermined pressures to provide repeatable LT (10 N) and pain General management and marking (75 N) stimulation of the wound, as previously described.13 On the day of each trial, lambs were yarded and drafted from their dams into a holding yard where they were held separately from their Evidence of local anaesthesia, primary (wound) and secondary (tissue surrounding wound) allodynia (pain response to non-painful stimuli) and hyperalgesia (exaggerated response to painful stimuli) Table 1. Treatment groups and total number of lambs in each treatment were assessed at each site. Typical LT- and pain-induced involuntary group in Trials 1 and 2 reflexes and motor responses in the rump and head were measured using a customised numerical rating scale (NRS).13 Rump response Group No. of Mulesing Tail Treatment scores were graded as: 0, no response; 1, minor involuntary motor lambs docking response such as local skin twitch, subcutaneous muscle twitch or anal contraction; 2, partial rump withdrawal reflex such as multiple sub- Trial 1 cutaneous muscle group contraction and/or lifting of the tail; 3, full 1 5 No No Control rump withdrawal reflex with lifting of the rump off the cradle. Facial 2 6 Yes Hot iron Topical anaesthetic response scores were graded as: 0, no response; 1, minor facial ‘aware- 3 6 Yes Hot iron No anaesthetic ness’ such as eye widening, blinking or nasal flaring; 2, partial startle 4 6 No Hot iron No anaesthetic reflex of the head such as slight lifting of the snout or partial head Trial 2 rotation; 3, full startle reflex of the head, resulting

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on No anaesthetic reflex of the head such as slight lifting of the snout or partial head Trial 2 rotation; 3, full startle reflex of the head, resulting in a major move- 1 14 No No Control ment such as lifting the head off the cradle, full head jerk or full head 2 14 Yes No Topical anaesthetic rotation. Scores for each site were added to achieve a total score for 3 14 Yes No No anaesthetic each lamb. Total scores were calculated out of 30 for skin sensitivity around the mulesed area and out of 54 for direct wound sensitivity. © 2013 The Authors Australian Veterinary Journal © 2013 Australian Veterinary Association Australian Veterinary Journal Volume 91, No 4, April 2013 161 PRODUCTION ANIMALS Measurement of times to mother up and to feed compare differences within time-points. For all statistical calculations, Lambs aged 6–8 weeks from 3-year-old ewes were used for these trials. P < 0.05 was considered statistically significant. In each trial, lambs and mothers (dams) were observed in groups of PRODUCTION ANIMALS mixed treatment. Lambs and dams were identified in pairs by col- Results oured marker for observation of times to mother up and to feed. In Trial 1, there were three groups of 7–8 lambs and dams and in Trial Body weights 2, six groups of 7. There were no twins included in the trial. Trial 1. The change in body weight from pretreatment (11.86 ⫾ 0.32 kg) to 24 h post-treatment (12.26 ⫾ 0.32 kg) was significant Time (s) taken for individual lambs to find their mother, and to feed (P = 0.03). Treatment (P = 0.59) and treatment by time interaction were recorded using a stopwatch (DSE® digital LCD). Time to mother (P = 0.297) were not significant. up was measured as time taken for the lamb to locate and be recog- nised by its mother from its

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LCD). Time to mother (P = 0.297) were not significant. up was measured as time taken for the lamb to locate and be recog- nised by its mother from its time of release into the yard. Time to feed Trial 2. The change in body weight from pretreatment (21.05 ⫾ was measured as the time taken for the lamb to begin suckling from 0.49 kg) to 24 h post-treatment (20.48 ⫾ 0.45 kg) was not significant the ewe from its time of release from the yard. This did not always (P = 0.404). Treatment (P = 0.737) and treatment by time interaction happen simultaneously with mothering up. (P = 0.999) were not significant. During Trial 1, we observed that several ewes displayed circling behav- Times to mother up and to feed iour when lambs attempted to feed, delaying the time to feed response. Trial 1. Results from Trial 1 are displayed in Figure 1. Lambs that had We postulated that the odour from singed wool associated with the HI been HI tail docked with or without mulesing and/or treatment with tail docking wound might have been confusing the ewes and thus topical anaesthetic dressing had significantly (P < 0.05) longer mean confounding the response. To investigate this further, a fourth group times to mother up and to feed than undocked/unmulesed control of lambs that underwent HI tail docking only (n = 6, no mulesing, and lambs. Behaviour of ewes, including circling of lambs and smelling of no topical anaesthetic treatment) was included to assess the times to the perineum, was noted when lambs were placed in the pen with mother up and to feed. These lambs underwent the same treatment dams. There was no significant difference in time to mother up sequence and were released individually into the pen of the six dams (P ⱖ 0.13) or time to first feed (P ⱖ 0.12) between any of

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ce in time to mother up sequence and were released individually into the pen of the six dams (P ⱖ 0.13) or time to first feed (P ⱖ 0.12) between any of the groups immediately following treatment. of lambs that were HI tail docked, regardless of mulesing treatment. Trial 2. Results from Trial 2 are displayed in Figure 2. Lambs in this Assessment of pain-related behaviours group had been previously tail docked and thus underwent mulesing In Trial 1, pain-related behaviour was assessed at 1 h and 24 h post- only. Field observations indicated that dams did not display the cir- mulesing using the NRS developed previously.13 A trained observer cling avoidance behaviour that had characterised observations in the (experienced animal scientist ‘blind to treatment’) observed the lambs Trial 1 groups of lambs that had undergone HI tail docking. This was 24 h post-procedure. Individual lambs were given a score between reflected in the time to mother up, which did not differ significantly 0 and 3: 0, no pain-related behaviour; 1, mild abnormalities of posture, between the groups and was similar to the control group from Trial 1. gait or behaviour such as mild kyphosis without hyperextension of However, there was a trend towards a treatment effect on time to feed, hindlegs, ventral recumbency with hindlegs partially extended or mild although not significant (P = 0.1). Mulesed, non-anaesthetised lambs stiffening of gait without overt limping or leg dragging; 2, moderate took longer to begin suckling (38 s) than either control lambs (22 s) or abnormalities of posture, gait or behaviour such as ‘statue standing’ mulesed lambs treated with topical anaesthesia (12 s). with head down and prominent kyphosis, moderate stiffening or slowing of gait or hyperextension

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mulesed lambs treated with topical anaesthesia (12 s). with head down and prominent kyphosis, moderate stiffening or slowing of gait or hyperextension and/or abduction of hindlegs, ventral recumbency with hindlegs fully extended; 3, display of severe abnormalities of posture, gait or behaviour such as marked agitation with twisting or writhing, high frequency of postural change from lying to kneeling or standing, distressed vocalisation, lateral or pros- trate lying, kneeling, dog sitting or tremors, shaking or lip curling. Statistical analysis Data were analysed using GenStat® version 10.0 (VSN International Ltd, Hemel Hempstead, UK). One-way analysis of variance was used to measure effects of treatment on times to mother up and to feed. Data were tested for normality and where necessary transformed into a logarithm form to normalise distribution. A repeated measures residual maximum likelihood estimation for linear mixed models was used to analyse weight data and NRS scores from sensitivity testing and behavioural observations. For all treatments, where a significant Figure 1. Mean ⫾ SEM times taken for lambs in Trial 1 to mother up and time and treatment interaction was found, post-hoc pair-wise to feed immediately after treatment. HI, hot iron; TA, topical anaesthesia comparisons using least significant differences were performed to (Tri-Solfen®); NA, no anaesthesia. © 2013 The Authors 162 Australian Veterinary Journal Volume 91, No 4, April 2013 Australian Veterinary Journal © 2013 Australian Veterinary Association PRODUCTION ANIMALS Response to light touch and pain stimulation of the wound and surrounding skin Pre-mulesing. There was very little to no response to LT or pain PRODUCTION ANIMALS stimulation of the intact skin of the breech prior to

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ounding skin Pre-mulesing. There was very little to no response to LT or pain PRODUCTION ANIMALS stimulation of the intact skin of the breech prior to mulesing. Mean response scores from the five LT testing sites (maximum possible score of 30) and nine pain sites (maximum possible score of 54) were ⱕ0.04 ⫾ 0.04 and ⱕ0.75 ⫾ 0.22, respectively, across both trials. There were no significant differences between groups within each trial. Post-mulesing. Mean responses to pain and LT stimulation of the wound and peri-wound in Trial 1 are shown in Figures 3 and 4, respec- tively. There was significant effect of treatment on responses to pain and LT stimulation of the wound (both P < 0.001) and peri-wound Figure 2. Mean ⫾ SEM times taken for lambs in Trial 2 to mother up and (both P < 0.001). A significant time by treatment interaction was also to feed immediately after treatment. Lambs in Trial 2 had been tail docked prior to mulesing. TA, topical anaesthesia (Tri-Solfen®); NA, no seen for LT and pain stimulation of the wound (both P < 0.001) and anaesthesia. pain stimulation of the peri-wound (P < 0.001). Primary hyperalgesia Figure 3. Mean ⫾ SEM total head and rump response scores to pain stimulation of the wound and peri-wound surfaces before (0 min) and after treatment (Trial 1). TA, topical anaesthesia (Tri-Solfen®); NA, no anaesthesia. Figure 4. Mean ⫾ SEM total head and rump response scores to light touch stimulation of the wound and peri-wound surfaces before (0 min) and after treatment (Trial 1). TA, topical anaesthesia (Tri-Solfen®); NA, no anaesthesia. © 2013 The Authors Australian Veterinary Journal © 2013 Australian Veterinary Association Australian Veterinary Journal Volume 91, No 4, April 2013 163 PRODUCTION ANIMALS and allodynia (of the

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ournal © 2013 Australian Veterinary Association Australian Veterinary Journal Volume 91, No 4, April 2013 163 PRODUCTION ANIMALS and allodynia (of the wound) developed within 1 min of mulesing in anaesthetised lambs, but not in control lambs and mulesed lambs non-anaesthetised lambs, but not in lambs in the control group or that received topical anaesthesia. Mulesed lambs treated with topical PRODUCTION ANIMALS mulesed lambs that received topical anaesthesia. Mulesed lambs that anaesthesia had significantly lower response scores to pain stimula- received topical anaesthesia also exhibited significantly less secondary tion of the mulesing wound (P < 0.001) and surrounding skin hyperalgesia (P < 0.001) and allodynia (P = 0.05) than mulesed, non- (P = 0.016) at 1 min and 24 h post-mulesing than mulesed, non- anaesthetised lambs. Response scores of mulesed, non-anaesthetised anaesthetised lambs. Primary and secondary hyperalgesia response lambs to LT and pain stimulation of the mulesing wound were scores of mulesed lambs that received topical anaesthesia did not significantly higher than those of the control lambs and mulesed differ significantly from controls until 24 h post-mulesing. There was lambs that received topical anaesthesia, at both 1 min and 24 h no significant difference in primary or secondary allodynia found post-mulesing. between treatment groups, despite a trend for mulesed, non- anaesthetised lambs to have higher NRS scores than mulesed lambs Mean responses to pain and LT stimulation of the wound and peri- that received topical anaesthesia and control lambs. wound in Trial 2 are shown in Figures 5 and 6, respectively. There was a significant effect of treatment (P < 0.001) and time by treatment Pain-related behaviour interaction in responses to

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5 and 6, respectively. There was a significant effect of treatment (P < 0.001) and time by treatment Pain-related behaviour interaction in responses to pain stimulation of the mulesing wound Trial 1. Behavioural data are shown in Figure 7. There was a signifi- (P < 0.001) and surrounding skin (P = 0.016). Primary and secon- cant effect of treatment (P < 0.001), but no significant treatment by dary hyperalgesia developed within 1 min of mulesing in non- time interaction. Mulesed lambs treated with topical anaesthetic Figure 5. Mean ⫾ SEM total head and rump response scores to pain stimulation of the wound and peri-wound surfaces before (0 min) and after treatment (Trial 2). TA, topical anaesthesia (Tri-Solfen®); NA, no anaesthesia. Figure 6. Mean ⫾ SEM total head and rump response scores to light touch stimulation of the wound and peri-wound surfaces before (0 min) and after treatment (Trial 2). TA, topical anaesthesia (Tri-Solfen®); NA, no anaesthesia. © 2013 The Authors 164 Australian Veterinary Journal Volume 91, No 4, April 2013 Australian Veterinary Journal © 2013 Australian Veterinary Association PRODUCTION ANIMALS PRODUCTION ANIMALS Figure 7. Mean ⫾ SEM numerical rating scores for pain-related behaviour of three dif- ferent treatment groups of lambs following mulesing and/or tail docking compared with control lambs at 1 h (grey) and 24 h (black) after mulesing (Trial 1). HI, hot iron; TA, topical anaesthesia (Tri-Solfen®); NA, no anaesthesia. displayed significantly lower pain-related behaviour scores compared small pen of 6 ¥ 4 m, such that lambs only had to cross a short distance with mulesed, non-anaesthetised lambs at both 1 h and 24 h post- to find their dams. It is possible that these results could be magnified mulesing. Mulesed lambs

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sed, non-anaesthetised lambs at both 1 h and 24 h post- to find their dams. It is possible that these results could be magnified mulesing. Mulesed lambs treated with topical anaesthetic did not in a larger field. differ significantly from unmulesed controls. Our results demonstrating significant wound anaesthesia within 1 min of the application of topical anaesthesia concur with previous Discussion findings that have noted that mulesing wounds treated with immedi- ate postoperative topical anaesthesia are desensitised within 1–3 min Results from our trials indicate that significant pain alleviation and of mulesing. As such, it would seem pain is unlikely to have impaired improved recovery can be achieved in lambs for up to 24 h after the times to mother up or to feed in lambs treated with topical mulesing through the use of topical anaesthesia. This extends data anaesthesia.13 from previous research that topical anaesthesia is efficacious up to 8 h post-mulesing.13,15 The results of wound sensitivity testing and behavioural observations in these trials are consistent with and extend our previous findings In Trial 1, HI tail docking seems to have been the major factor delaying that topical anaesthesia for mulesing wounds is efficacious up to 8 h the times to mother up and to feed. This could be attributed to the post-treatment.13,15 The present study has confirmed anecdotal obser- invasive nature of the procedure, as it is well documented that tail vations that wound anaesthesia persists up to 24 h post-mulesing. A docking elicits a significant pain response in lambs.9,16–18 It is also significant and increasing hyperalgesic wound response was observed hypothesised that the odour of the cauterised wound may act as a in mulesed, non-anaesthetised lambs

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creasing hyperalgesic wound response was observed hypothesised that the odour of the cauterised wound may act as a in mulesed, non-anaesthetised lambs over 24 h in both trials and deterrent to the mother when lambs approach them and this was this effect was significantly ameliorated by treatment with topical observed through the avoidance behaviour displayed by the ewes to anaesthesia. the lambs, evident in Trial 1, but not in Trial 2 where lambs were mulesed without tail docking. Ewes in Trial 1 appeared to spend more Our results do not concur so readily with previous findings by Paull time smelling the lambs, particularly the perineum, before allowing et al,15 who reported that pain-related behaviours in lambs treated contact and eventually, feeding. However, it is important to note that with topical anaesthesia developed between 4 and 8 h post-mulesing. differences between groups were only a matter of seconds and are Our previous trials have revealed minimal evidence of wound pain or therefore not likely to be clinically relevant. Further analysis of this pain-related behaviour at 1, 4 or 8 h post-mulesing in lambs treated phenomenon may provide useful information to researchers and pro- with Tri-Solfen13 and we now report minimal evidence of pain-related ducers as to how mothering up can be affected by various husbandry behaviour at 24 h post-mulesing. This variation may be explained by procedures. differences in methodology.Videotape analysis of lamb behaviour was used in the Paull et al. trial,15 which is likely to be more sensitive to In Trial 2, unrecorded observations suggested that pain-related behav- abnormal behaviours than the NRS field observations used in our iour may have interfered with feed-seeking behaviour in some lambs trials. However, it is

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normal behaviours than the NRS field observations used in our iour may have interfered with feed-seeking behaviour in some lambs trials. However, it is also possible that methodology used by Paull undergoing mulesing without topical anaesthesia, but this was not et al.15 trial resulted in exaggerated pain-related behavioural responses apparent in control lambs or lambs treated with topical anaesthesia. for the lambs. In that trial, lambs were held in small indoor pens and Again it should be noted that any differences between groups underwent repeated handling at 30 min and 6 h post-treatment for observed were only a matter of 10–20 s, which is unlikely to be clini- blood sampling, which may have heightened their stress responses and cally relevant. However, ewes in these trials were held in a relatively also exacerbated bleeding and pain from the wound because of the © 2013 The Authors Australian Veterinary Journal © 2013 Australian Veterinary Association Australian Veterinary Journal Volume 91, No 4, April 2013 165 PRODUCTION ANIMALS repeated physical disturbance. Our trials were designed to mimic nerve endings and providing a barrier against ongoing environmental the field situation such that lambs were returned to their dams and exposure and tactile stimulation.30–33 PRODUCTION ANIMALS left undisturbed in a pasture-covered paddock between behavioural assessments. This may have reduced pain and pain-related behaviour in these lambs. It is important to note that Paull et al. found that lambs Conclusion treated with a combination of topical anaesthetic and a non-steroidal The topical anaesthetic, antiseptic and haemostatic product antiinflammatory drug (NSAID) did not display a significant occur- Tri-Solfen® developed for pain alleviation at mulesing has a

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and haemostatic product antiinflammatory drug (NSAID) did not display a significant occur- Tri-Solfen® developed for pain alleviation at mulesing has a prolonged rence of pain-related behaviours in comparison with unmulesed con- duration of action up to 24 h post-treatment. It is hypothesised that trols between 4 and 12 h.15 Thus the use of NSAIDs should be further the combination of local anaesthesia, haemostatic and vasoconstrictor explored and considered as an option for further reducing postopera- action of epinephrine with inhibition of the inflammatory cascade and tive pain. the barrier effect of the gel base of the product may explain the finding of prolonged wound anaesthesia observed in the present study. The technique of wound sensitivity testing over the first 8 h following mulesing with or without treatment with topical anaesthesia has been previously described.13 The results from the present study indicate Acknowledgments that treatment was still effective at 24 h post-mulesing using the same wound pain assessment techniques. Hypersensitivity to LT and pain The financial support of the Australian Research Council, Bayer stimulation evident within the wound and the surrounding areas in Animal Health Australia and Animal Ethics Pty Ltd is gratefully the first minute after mulesing in non-anaesthetised lambs was fol- acknowledged. The authors thank Mr Geoff Moore and staff at ‘Yerilla’ lowed by increased allodynia and primary and secondary hyperalgesia for their technical and logistical support. We greatly appreciate the at 24 h post-mulesing. There was evidence of significant and persist- statistical advice from Dr Peter Thomson from the University of ent wound anaesthesia at 24 h post-mulesing in lambs treated with Sydney. topical

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ist- statistical advice from Dr Peter Thomson from the University of ent wound anaesthesia at 24 h post-mulesing in lambs treated with Sydney. topical anaesthesia. Local anaesthetic agents act by inhibiting the generation and conduc- References tion of ionic fluxes required for the conduction of nerve impulses 1. Baillie BG. Management practices for controlling flystrike. In: Proceedings of responsible for the sensation of pain. These anaesthetics are readily the National Symposium on the Sheep Blowfly and Flystrike in Sheep, New South absorbed through mucous membranes and damaged skin to reach the Wales Department of Agriculture, Sydney, 25–27 June, 1979;159–173. nerve fibres. Tri-Solfen contains lidocaine hydrochloride (40.6 g/L) 2. Graham NPH. The problem of flystrike in sheep in Australia. In: Proceedings of the National Symposium on the Sheep Blowfly and Flystrike in Sheep, New South and bupivacaine hydrochloride (4.5 g/L) as the active anaesthetic Wales Department of Agriculture, Sydney, 25–27 June, 1979;1–5. agents and adrenaline tartrate (24.8 mg/L) as a vasoconstrictor. The 3. Simpson I. Management procedures for prevention and control of flystrike. In: half-life for lidocaine in humans is reported to be 1.5–2 h and that of Proceedings of sheep blowfly and flystrike management workshop, Trangie, 1987. bupivacaine is 2.7 h in adults and 8.1 h in neonates. When used topi- 4. Hart RJ. Review of breech strike and the mules operation. In: Second national cally, adrenaline would slow the rate of systemic absorption of the two symposium on the sheep blowfly and flystrike in sheep. NSW Dept of Agriculture, anaesthetic agents and reduce wound haemorrhage. The reduced rate Sydney, 1983. of systemic absorption keeps the active ingredients

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pt of Agriculture, anaesthetic agents and reduce wound haemorrhage. The reduced rate Sydney, 1983. of systemic absorption keeps the active ingredients concentrated at 5. Dun RB, Donnelly FB. Effectiveness of the Mules operation at lamb marking. Aust J Exp Agric Anim Husb 1965;5:6–10. the site and slows the metabolism of the agents, prolonging the inten- 6. Chapman RE, Fell LR, Shutt DA. A comparison of stress in surgically and sity and duration of local anaesthesia. non-surgically mulesed sheep. Aust Vet J 1994;71:243–247. 7. Cronin GM, Barnett JL, Edge MK, Hemsworth PH. Identifying animal welfare Local anaesthetics can provide rapid and prolonged anaesthesia issues for sheep in Australia. Wool Technol Sheep Breeding 2002;50:534–540. 8. Fell LR, Shutt DA. Behavioural and hormonal responses to acute surgical stress when applied to open wounds19–25 and can also prevent or reduce the in sheep. Appl Anim Behav Sci 1989;22:283–294. subsequent pain escalation response.26–28 The vasoconstrictive prop- 9. Grant C. Behavioural responses of lambs to common painful husbandry erties of adrenaline slow the blood flow to the wound, thereby sup- procedures. Appl Anim Behav Sci 2004;87:255–273. 10. James P. Genetic alternatives to mulesing and tail docking in sheep: a review. pressing the inflammatory cascade, resulting in a reduction in Aust J Exp Agric 2006;46:1–18. associated pain caused by accumulation of inflammatory mediators, 11. James P. Genetic alternatives to mulesing and tail docking in sheep. Australian including cytokines and histamines.29 This may provide an addi- Wool Innovation Limited, Sydney, 2004. tional explanation for the prolonged efficacy of the combination 12. Scobie DR, O’Connell D, Morris CA, Hickey SM. A preliminary genetic analysis of

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04. tional explanation for the prolonged efficacy of the combination 12. Scobie DR, O’Connell D, Morris CA, Hickey SM. A preliminary genetic analysis of breech and tail traits with the aim of improving the welfare of sheep. Aust J topical anaesthesia/vasoconstrictor preparation. Agric Res 2007;58:161–167. 13. Lomax S, Sheil M, Windsor PA. Impact of topical anaesthesia on pain allevia- Another hypothesis for the long-term efficacy of the topical anaes- tion and wound healing in lambs after mulesing. Aust Vet J 2008;86:159–168. thesia is the presence of a barrier effect from inclusion of a gel base in 14. Nowak R. Neonatal survival: contributions from behavioural studies in sheep. Appl Anim Behav Sci 1996;49:61–72. the preparation. We previously found that mild pain alleviation was 15. Paull DR, Lee C, Colditz IG, Atkinson SJ, Fisher AD. The effect of a topical observed through the use of a placebo agent that consisted of the gel anaesthetic formulation, systemic flunixin and carprofen, singly or in combina- base without the local anaesthetic or vasoconstrictor actives.13 This is tion, on cortisol and behavioural responses of Merino lambs to mulesing. Aust Vet J 2007;85:98–106. also consistent with the findings of published studies on skin incisions 16. Graham MJ, Kent JE, Molony V. Effects of four analgesic treatments on the and open wounds in humans, where barrier dressings have significant behaviouraland cortisol responses of 3-week-old lambs to tail docking. Vet J benefits for wound healing and pain attenuation by coating damaged 1997;153:87–97. © 2013 The Authors 166 Australian Veterinary Journal Volume 91, No 4, April 2013 Australian Veterinary Journal © 2013 Australian Veterinary Association PRODUCTION ANIMALS 17. Jongman EC, Morris JP,

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urnal Volume 91, No 4, April 2013 Australian Veterinary Journal © 2013 Australian Veterinary Association PRODUCTION ANIMALS 17. Jongman EC, Morris JP, Barnett JL, Hemsworth PH. EEG changes in 4-week-old 26. Dahl JB, Brennum J, Arendt-Nielsen L, Jensen TS, Kehlet H. The effect of lambs in response to castration, tail docking and mulesing. Aust Vet J 2000; pre- versus post-injury infiltration with lidocaine on thermal and mechanical 78:339–343. hyperalgaesia after heat injury to the skin. Pain 1993;53:43–51. PRODUCTION ANIMALS 18. Kent JE, Molony V. Changes in plasma cortisol concentration in lambs of 27. Lam KW, Pun TC, Ng EH, Wong KS. Efficacy of preemptive analgesia for wound three ages after three methods of castration and tail docking. Res Vet Sci 1993;55: pain after laproscopic operations in infertile women: a randomised, double blind 246–251. and placebo control study. Biol J Obstet Gynaecol 2004;111:340–344. 19. Brofeldt B, Cornwell P, Doherty D, Batra K, Gunther R. Topical lidocaine in the 28. Pogatzki EM, Vandermeulen EP, Brennan TJ. Effect of plantar local anaesthetic treatment of partial-thickness burns. J Burn Care Rehabil 1989;10:63–68. injection on dorsal horn neuron activity and pain behaviours caused by incision. 20. Jellish WS, Gamelli RL, Furry PA, McGill VL, Fluder EM. Effect of topical local Pain 2002;97:151–161. anesthetic application to skin harvest sites for pain management in burn patients 29. Dias MP, Newton DJ, McLeod GA, Khan F, Belch JJF. The inhibitory effects of undergoing skin-grafting procedures. Ann Surg 1999;229:115–120. local anaesthetics on the vascular flare responses to bradykinin and substance 21. Kokinsky E, Cassuto J, Sinclair R et al. Topical wound anaesthesia in children: P in human skin. Anaesthesia

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responses to bradykinin and substance 21. Kokinsky E, Cassuto J, Sinclair R et al. Topical wound anaesthesia in children: P in human skin. Anaesthesia 2008;63:151–155. a temporary postoperative pain relief. Acta Anaesthesiol Scand 1999;43:225–229. 30. Schuren J, Becker A, Sibbald RG. A liquid film-forming acrylate for peri-wound 22. Sinclair R, Cassuto J, Hogstrom S. Topical anaesthesia with lidocaine aerosol in protection: a systematic review and meta-analysis (3MTM CavilonTM no-sting the control of postoperative pain. Anaesthesiology 1988;68:895–901. barrier film). Int Wound J 2005;2:230–238. 23. Sinclair R, Westlander G, Cassuto J, Hedner T. Postoperative pain relief by 31. Cameron J, Hoffman D, Wilson J, Cherry G. Comparison of two peri-wound topical lidocaine in the surgical wound of hysterectomized patients. Acta skin protectants in venous leg ulcers: a randomised controlled trial. J Wound Care Anaesthesiol Scand 1996;40:594–598. 2005;14:233–236. 24. Smith GA, Strausbaugh SD, Harbeck-Weber C et al. Comparison of topical 32. Neander K, Hesse F. Wound edge protection in chronic wounds. J Wound Care anesthetics without cocaine to tetracaine-adrenaline-cocaine and lidocaine infil- 2003;12:369–371. tration during repair of lacerations: bupivacaine-norepinephrine is an effective 33. Rolstad B, Borchert K, Magnan S, Scheel N. A comparison of an alcohol-based new topical anesthetic agent. Pediatrics 1996;97:301–307. and a siloxane-based peri-wound skin protectant. J Wound Care 1994;3:367– 25. Stewart A, Simpson P, Rosenberg N. Use of topical lidocaine in pediatric 368. laceration repair: a review of topical anaesthetics. Pediatr Emerg Care 1998;14: 419–423. (Accepted for publication 9 September 2012) BOOK REVIEW Color atlas of veterinary

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review of topical anaesthetics. Pediatr Emerg Care 1998;14: 419–423. (Accepted for publication 9 September 2012) BOOK REVIEW Color atlas of veterinary histology. 3rd edn. Edited by WJ Bacha and LM Bacha. Wiley-Blackwell, West Sussex, 2012. 356 pages. Price A$125.00. ISBN 978 0470958513. T he 3rd edition of this hardcover text covers histology in the is rudimentary and would not be of particular use to either students major veterinary species (dog, cat, horse, cow, sheep, goat, or pathologists as a reference. pig and chicken) and is designed as a learning tool for students. This edition is slightly longer and the layout of the text improved and more user friendly, especially the headings, compared with the The book begins with a brief introduction to histology, including 2nd edition, but the content is essentially unchanged. Helpful hints tips for viewing slides and setting up a microscope. All tissues and and root word boxes are a useful addition. Most of the illustrations systems are discussed chapter by chapter. There is a short introduc- from the 2nd edition are included, with some new ones. The CD is tion to each tissue or system, followed by annotated photomicro- new for the 3rd edition, but contains only the illustrations, which graphs relevant to the appropriate species. All photomicrographs are viewed via an index or search function. are in colour and diagrams are in black and white. The chapter on haematology is predominantly illustrated with blood smears rather than histological sections. It identifies the normal blood compo- The text is illustrative rather than an in-depth description of tissue. nents for each species and mentions common variations seen on Many of the medical histology books have such detailed analysis normal smears. The text concludes

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each species and mentions common variations seen on Many of the medical histology books have such detailed analysis normal smears. The text concludes with a glossary and index. and briefly cover EM and cell cycles, topics that are not covered in this atlas. However, I love the extensive coverage of species-specific The introductory chapter is short and succinct, but covers all that variations, which obviously cannot be found in a medical histology would be required by most veterinary students. Headings are con- text. sistent and easily recognised and the photomicrographs are well laid out. Boxes containing chapter summaries are not always clear The text would be helpful to students studying veterinary histology at a glance, because of poor text formatting. Helpful hints, high- and as a reference for both veterinarians in practice and veterinary lighted in blue boxes, are very useful and cover topics such as how pathologists. to recognise certain tissues and suggestions for examining certain tissues and slides. The glossary may be useful for some, but the Priscilla Hodge internet is likely to have made this section somewhat redundant. Although most of the illustrations are of high quality, a proportion doi: 10.1111/avj.12035 is not, particularly the larger pictures. The chapter on bone marrow © 2013 The Authors Australian Veterinary Journal © 2013 Australian Veterinary Association Australian Veterinary Journal Volume 91, No 4, April 2013 167