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    Efficacy of articaine hydrochloride for disbudding in goat kids and velvet antler removal in red deer, and novel disbudding methods for goat kids : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University, Palmerston North, New Zealand
    (Massey University, 2019) Venkatachalam, Dinakaran
    Painful husbandry procedures are routinely performed in farm animals all over the world. Most of these procedures can be humanely performed under local anaesthesia. Lignocaine is the most commonly used local anaesthetic in veterinary medicine. Even though lignocaine is a cheap and effective local anaesthetic, its use in goat kids and deer has been a concern. In goat kids, lignocaine has been reported to produce toxicity following cornual nerve block. In deer, the presence of lignocaine residue in the harvested velvet antlers following ring block has been a concern as one of its metabolites, 2,6-dimethylaniline (DMA) has been classified as a possible carcinogen in humans. Articaine hydrochloride is an amide-type local anaesthetic with unique pharmacological properties such as rapid hydrolysis in plasma to an inactive metabolite and high lipid solubility. It is widely used in humans for local and regional nerve blocks in dentistry. Several studies in humans suggested that articaine hydrochloride was effective and safer than lignocaine. Given concerns on the use of lignocaine in goat kids and deer, a series of studies were conducted to evaluate the safety and efficacy of articaine hydrochloride as an alternative to lignocaine hydrochloride for disbudding in goat kids and velvet antler removal in deer. As there is a paucity of data on the toxicity of lignocaine in goat kids, the thesis has also investigated the toxicity of lignocaine hydrochloride in goat kids. In addition, novel analgesic and disbudding techniques for goat kids were evaluated. The dose-ranging studies in goat kids suggested that doses up to 8 mg kg–1 and 7 mg kg–1 of articaine hydrochloride and lignocaine hydrochloride, respectively, can be safely used for perineural injections. Pharmacokinetic studies demonstrated that articaine hydrochloride was rapidly hydrolysed and eliminated in goat kids. The elimination half-life of articaine (1.26 ± 0.34 hours) was determined to be shorter than the elimination half-lives of lignocaine (1.71 ± 0.51 hours) and lignocaine’s metabolite, monoethylglycinexylidide (3.19 ± 1.21 hours) in goat kids. The total dose of articaine (16.24 ± 1.79 mg kg–1) required to produce convulsions in goat kids was higher than that of lignocaine (12.31 ± 1.42 mg kg–1). The mean convulsive plasma concentrations of articaine and lignocaine were 9.90 ± 2.38 µg mL–1 and 13.59 ± 2.34 µg mL–1, respectively. Both pharmacokinetic and toxicity data indicate that articaine has a greater margin of safety than lignocaine in goat kids. Cornual nerve block (0.5 mL/site) using articaine hydrochloride (1.5%) and lignocaine hydrochloride (1%) alleviated the acute pain during disbudding in goat kids. However, both the drugs provided analgesia only for a short time which necessitates the use of non-steroidal anti-inflammatory drugs (NSAIDs) for postoperative analgesia. In addition, the injection of these drugs at four sites to anaesthetise both the horn buds caused stress and pain in goat kids. Therefore, it is recommended to use sedatives and NSAIDs along with local anaesthetics for disbudding goat kids. However, future studies should evaluate the safety and efficacy of this protocol for disbudding in goat kids. Similar to goat kids, articaine was rapidly hydrolysed to the inactive metabolite, articainic acid, and rapidly eliminated in red deer. A ring block around the base of the antlers using 4% articaine hydrochloride (1 mL/cm pedicle circumference) provided effective analgesia for velvet antler removal in red deer. The results of the studies in red deer suggested that articaine could be a safe and effective local anaesthetic for velvet antler removal. Residue analysis of harvested antlers using liquid chromatography–mass spectrometry (LC–MS) method revealed that the concentrations of articaine and lignocaine in the harvested velvet antlers were similar. Further studies to evaluate the safety of articaine and its metabolites are warranted in target species before recommending articaine hydrochloride as an alternative to lignocaine hydrochloride for velvet antler removal. The analgesic efficacy of methoxyflurane and a novel topical local anaesthetic formulation for disbudding in goat kids were evaluated. Both methoxyflurane and the novel topical formulation provided cutaneous analgesia but did not provide sufficient analgesia for disbudding in goat kids. Further research is required to evaluate the efficacy of these novel analgesic techniques. The efficacy of mepacrine and eugenol for disbudding in goat kids were investigated following subcutaneous injection (0.2 mL) under the horn buds. Both eugenol and mepacrine produced necrosis of horn buds in goat kids but failed to stop horn bud growth. Injection of these compounds using a needle (26 G) and syringe was painful but no pain-related behaviours were seen after the injection. Future studies should evaluate different injection volumes and different non-invasive or minimally invasive administration techniques to increase the efficacy of this novel technique. Refinement of this novel technique might provide a simple, fast, safe and effective way to stop horn bud growth in goat kids.
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    Evaluation of strategies for alleviating dehorning distress in calves : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Physiology at Massey University
    (Massey University, 1997) McMeekan, Cheryl Maree
    Animal welfare has been the focus of greater public attention in recent decades, increasing the demand for scientific enquiry into the effects of particular agricultural practices on the well-being of farm animals. The present study monitored the behavioural and plasma cortisol responses of 3-4 month-old calves to assess the distress caused by scoop dehorning during the first 9 hours after horn removal, and the extent that this distress may be reduced by minimising the scoop wound depth, or by giving prior injections of local anaesthetic and/or a non-steroidal anti-inflammatory drug (NSAID). At the investigated scoop wound depths, the cortisol response which followed dehorning (consisting of an initial peak, followed by a decline at 2 hours to plateau values which did not return to control levels until about 7 hours after treatment), did not differ significantly between deep scoop and shallow scoop dehorning. However, NSAID administration abolished the plateau cortisol phase. Local anaesthetic plus the NSAID abolished both the initial cortisol peak and following plateau response, such that the total integrated cortisol response was not significantly different from control calves. Likewise the behaviour expressed by scoop dehorned calves was most similar to that of pain-free control calves, when both local anaesthetic and the NSAID was given prior to horn removal, compared to either drug alone, or neither. This infers that the distress caused by scoop dehorning in calves has two main components: an initial amputation pain and a more slowly developing inflammation pain, the former alleviated by local anaesthetic and the latter by NSAID. Administration of local anaesthetic while abolishing the cortisol response during its nerve-blockade action, did not significantly reduce the overall cortisol response due to a marked rise after nerve-blockade effects ended. This suggests scoop dehorned calves despite being given local anaesthetic, still experience notable pain in the hours following scoop dehorning which is likely to be inflammation-induced. The results of this study suggest little benefit in implementing a shallow scoop strategy in order to reduce post-dehorning pain-induced distress. Rather, administration of an anti-inflammatory analgesic in addition to local anaesthetic prior to scoop dehorning is likely to offer improved pain relief in calves undergoing this amputation procedure.
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    Prevention of antler growth in deer : a thesis presented in partial fulfilment of the requirements for the degree of Master in Veterinary Clinical Science at Massey University
    (Massey University, 1996) Weilburg, Vera
    The behavioural measures of 31 red and 39 fallow deer yearlings prior to, during and following application of rubber ring to prevent antler growth were determined. Animals were mechanically or manually restrained and treated according to their random allocation to one of the following groups: control (C), local anaesthesia only(LC), local anaesthesia and rubber ring application (LR) , rubber ring application only(R). In a further field trial 45 yearling red deer stags and 84 yearling fallow bucks were randomly allocated to control or rubber ring application. In both studies the development of the pedicle/antler post treatment was examined at intervals to investigate the percentage of loss of pedicle/antler due to the treatment and to detect possible side effects of the treatment. In red deer during the first three hours post treatment a significant increase in walking, standing and feeding and a decrease in lying were seen in the R group. Twenty minutes after treatment the R group showed a significantly higher frequency of scratching. In fallow deer a significant increase in frequency of ear flicks was observed in the R group until six hours post treatment. Other activities (walking,standing, lying) varied significantly at some time periods but no consistent patterns were observed. In both species a substantial reduction of the pedicle/antler could be observed two to four weeks after application of rubber rings. However, the loss of distal parts of the pedicle/antler varied in percentage and time until the loss. A rate of 38-100% regrowth occurred in the first study in fallow and red deer, respectively. In red deer the application of rubber rings stopped further antler growth in 36 of 37 stags thirty days after treatment. The loss of pedicle/antler occurred in 60-66.7%. In fallow deer 93% pedicle/antler loss occurred in bucks. A rate of 10 % regrowth occurred. No infections or other untoward side effects of the treatment were seen.
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    Evaluation of dehorning distress and its alleviation in calves : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Physiology at Massey University
    (Massey University, 2002) Sylvester, Shauna P
    In this thesis, the pain-induced distress caused by the husbandry practice of dehorning cattle is assessed and methods to alleviate it are evaluated. At the time this work was conducted there were no comprehensive studies on the effects of amputation dehorning upon the welfare of the cattle. The aims of the study were to assess the distress response after dehorning and to explore the possibilities of alleviating that distress through the use of different dehorning tools, local anaesthetic and/or cautery of the scoop wound. Changes in plasma Cortisol concentrations and behaviour were used as indices of distress. It was anticipated that this research would provide scientific data to aid in the writing of welfare codes and advisory material concerning the dehorning of cattle. The Cortisol and behavioural responses of six-month-old male Friesian calves after treatment were studied. In the Cortisol studies, blood samples were taken by venipuncture from the jugular vein of each calf prior to, for the first 9 hours and at 36 h after treatment. Behavioural responses were scored by point scan behaviour sampling for the first 10 h after and on day two between 26 and 29 h after treatment. Amputation dehorning elicited a marked, biphasic Cortisol response that lasted six hours. Dehorning elicited similar Cortisol responses irrespective of the tool employed. ACTH bolus (iv. 0.28μg/kg) elicited a maximal Cortisol response. The similarity of the magnitude of the dehorning and ACTH responses suggests that dehorning was extremely distressing. The plateauing of the plasma Cortisol values between 1.5 and 3 hours after dehorning suggests the appearance of a second phase of pain, presumably from inflammation. Local anaesthesia virtually abolished the first three hours of the Cortisol response after dehorning, after which Cortisol concentrations rose transiently. Overall, this equated to a 50% reduction in the integrated Cortisol response. Cauterizing the scoop wounds effected a marginal reduction in the Cortisol response. The combination of local anaesthesia plus cauterizing the scoop wound virtually abolished the Cortisol response to amputation dehorning. This striking result is reminiscent of pre-emptive analgesia. The destruction of, and the prevention of sensitization of, nociceptors in the wound is thought to contribute to this effect. The four behaviours of tail shaking, head shaking, ear flicking and rumination, met the criteria required to use behaviour as evidence of distress. The interpretation of the behaviour data corresponded with that of the Cortisol data. Taken together, the Cortisol and behaviour data from this study, along with the subsequent work it generated, indicate that scoop dehorning is extremely noxious. If the cattle are older and amputation dehorning is necessary, it is recommended that local anaesthetic be given and if practicable combined with either ketoprofen (McMeekan et al., 1998b) or wound cautery. However, it is preferable to dehorn calves when they are younger by cautery disbudding (Petrie et al., 1996b).
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    Studies of local anaesthetics for velvet antler analgesia : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science at Massey University
    (Massey University, 2002) Bartels, Michele
    Velvet antler removal on commercial deer farms is the elective surgical amputation of a live, vascular and innervated tissue. This is ethically defensible only if the well-being of the stag is not unacceptably compromised, particularly in relation to operative and post-operative pain. Those removing velvet antlers are ethically bound to employ "best practice" analgesic techniques. Previous studies have shown that the local anaesthetic lignocaine HCL (2%) is most effective using the high dose ring block around the antler pedicle. The antlers from deer at the Massey University Deer Research Unit or a commercial deer farm in the Pohangina Valley, Manawatu were used for these analgesia onset and duration studies. The onset of analgesia was determined by electrically stimulating the velvet antler at 15-second intervals until behavioural responses ceased. Duration of analgesia was determined using a novel remote electrical stimulus, which registered the return of sensation in the antlers using behavioural responses. All treatments were administered in a ring block at dose rate of 1 ml/cm pedicle circumference. In Study 1(a), the onset times of analgesia after application of one of three treatments (2% lignocaine hydrochloride (L), 2% lignocaine hydrochloride with 8.4% sodium bicarbonate (LBC) and 0.5% commercially available bupivacaine (BC) were determined in antlers of 21 rising 1-year-old red, and wapiti hybrid stags. Each antler received two treatments (28 antlers per treatment). The mean onset time was 31(SE> 7.0) seconds for L, 21(SE>2.5) seconds for LBC and 48(SE>12.7) seconds for BC. The difference in mean onset between BC and LBC was significant (p=0.0225). In Study 1(b). antlers of 26 stags 2 years-of-age and older were allocated either L or LBC. Mean time of onset of analgesia for L was 31(SE>5.94) seconds and LBC was 36(SE>5.95) seconds. There was no significant difference between the two treatments. Duration of analgesia in Study 1 (a) was measured in eight antlers given L and nine antlers given BC. The mean duration for L was 88(SE>7.7) minutes, and for BC 273(SE>19) minutes (p>0.001). Antlers of 39 rising 1-year old stags were used for Study 2. The onset and duration of analgesia were compared following two combinations of L and a novel formulation of bupivacaine (BN). In study 2(a), "higt"(HLBN) (1.5% L and 0.5% BN) and "low"(LLBN) (1.0% L and 0.25% BN) concentrations of a mixture of Hgnocaine and bupivacaine were investigated for onset of analgesia on 25 antlers each. The mean time for onset of analgesia for HLBN was 37(SE>4.4) seconds and for LLBN, 55(SE >8.8) seconds (p=0.049). The mean duration (n=10 antlers/treatment) for HLBN was 406(SE >28.9) minutes compared with 333(SE>25.2) minutes for LLBN (p=0.041). In Study 2(b) antlers were treated with either 2% mepivacaine HC1 (M), 1.5% mepivacaine/I.5% lignocaine (ML), 1.5% mepivacaine/0.5% bupivacaine (BN) (MB) or 0.5% bupivacaine (BN) (n=7/treatment). Mean onset times were 30(SE ±12.3) seconds for M, 30(SE >6.6) seconds for MB, 34(SE>7.8) seconds for ML, and 86(SE >37.3) seconds for BN. There was no significant difference in mean onset times. Duration of the four treatments (n=7 antlers/treatment) was 271(SE> 26) minutes for M, 221(SE >19) minutes for ML, 421(SE >41) minutes for MB, and 461(SE >37) minutes for BN. There were differences in duration between treatments with bupivacaine and those without (p=±0.0001). The mean duration of analgesia following the novel bupivacaine formulation was significantly longer than that for the commercial formulation (p=0.001). In study 3, each step in the velvet antler removal procedure was timed and recorded. When both antlers on stags were given local anaesthetics together (n=16 antlers/treatment), the mean time between completion of the first ring block to the nick test on the first antler was 72 (range 52-151) seconds, while the mean time between completion of the second ring block and the nick test on the second antler was 70 (range 61-183) seconds. When only one antler was given a ring block, the time between completion of the block and the nick test was 42 (range 25-40) seconds. This study showed that the time interval between injection of a high dose ring block and application of the nick test by the experienced operator would rarely be less than 60 seconds when both antlers are treated together. Velvet antler removal can therefore be undertaken in a continuous sequence of activity eliminating the necessity of a wait time if 2% lignocaine is used at 1ml/cm antler pedicle circumference. In anticipation that studies of postoperative pain control will be needed in the future, a pilot trial testing one proposed method was undertaken. Fifteen 2-year old stags were given the tranquilliser, azaperone, to test whether it reduced the confounding effects of handling stress on plasma Cortisol concentrations. In addition, nine were given the non-steroidal inflammatory drug, flunixin meglumine, after velvet antler removal. Plasma cortisol concentrations were elevated in both groups. No significant difference was detected between the means of the control and NSAID treated groups over 5 hours.