Massey Documents by Type

Permanent URI for this communityhttps://mro.massey.ac.nz/handle/10179/294

Browse

Search Results

Now showing 1 - 10 of 11

Acute nociception in neonatal pigs undergoing tail docking : influence of docking method and age, evaluation of pain mitigation strategies, and assessment of the potential for longer-term pain : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University, Turitea, Palmerston North, New Zealand
(Massey University, 2016) Kells, Nikki J
Tail docking of pigs is performed routinely in many parts of the world to reduce the incidence of unwanted tail biting behaviour. Whilst tail biting can have serious welfare consequences for affected pigs, tail docking may also negatively affect pig welfare as a result of acute pain induced by the procedure itself, as well as through long-term changes in afferent neural inputs from the remaining tail stump. The aims of this thesis were to examine the influences of docking method and piglet age on acute nociceptive responses to tail docking; to evaluate the efficacy of selected anti-nociceptive strategies in mitigating acute nociceptive responses to tail docking; to determine whether docking method affects subsequent neural morphology of the healed tail stump. The minimal anaesthesia model (MAM), which involves analysis of electroencephalographic (EEG) data, was used to evaluate acute nociceptive responses and to ascertain the efficacy of anti-nociceptive strategies. Histopathological examination of tissue harvested from tail tips was performed to evaluate alterations in neural morphology that might be associated with long-term changes in pain processing. Comparison of the acute nociceptive responses of 2- and 20-day-old pigs to tail docking revealed little evidence of nociception in the younger age group compared with a typical response in the older pigs. In addition, total EEG power was lower in 2 day-old pigs. These results suggest that there are differences in either neural maturity, and/or in nociceptive processing between the two ages. Tail docking using cautery iron appears to be less acutely painful to pigs than tail docking using clippers. However, the longer-term pain consequences associated with the two methods need to be assessed before one method is recommended over the other. Prior application of a topical anaesthetic (EMLA) cream to the tail abolished EEG indicators of acute nociception in pigs tail docked using clippers, whereas prior administration of oral meloxicam had no effect on EEG responses. When no analgesia was used, tail docking using cautery iron ameliorated EEG indicators of nociception, relative to docking using clippers. Thus, prior administration of EMLA cream or the use of cautery iron in place of clippers have the potential to reduce the acute pain during routine tail docking. Acute EEG responses of pigs to the noxious stimulus of tail docking varied significantly with postnatal age over the first 15 days of life. Docking at 1 day-of-age elicited no EEG evidence of nociception, whilst cortical responsiveness to tail docking increased with postnatal age across the range of 5–15 days. This enhanced responsiveness may be due to the gradual withdrawal of fetal neurosuppressive mechanisms after birth, or rapid postnatal maturation of the cerebral cortex, or a combination of both. Tail docking using both side clippers and cautery iron resulted in the formation of neuromas, which have been associated with neuropathic pain, in the tail stump. Neither the proportion of tails with neuromas, nor the degree of abnormal nerve proliferation in the tail tip differed between the two docking methods. This suggests no longer-term welfare advantage of one method over the other, at least in terms of the potential for alterations in pain processing following stimulation of tail stump nociceptors. In terms of best practice guidelines for the performance of tail docking in pigs, this research provides support for current recommendations that tail docking, along with other painful husbandry procedures, be performed within one week of birth. Furthermore, tail docking with cautery induced less acute pain than docking with clippers, whilst both methods cause long-term changes in neural morphology in the tail stump. Docking using cautery may therefore be preferable to docking with clippers. Whilst cautery reduces the acute pain associated with docking relative to clippers, prior application of a topical anaesthetic cream (EMLA) completely abolished acute nociceptive responses to. Prior administration of topical anaesthesia, or the use of a cautery iron in place of clippers, has the potential to improve the welfare of pigs undergoing routine tail docking.
"Pharmacology of salicin derivatives in sheep" : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand
(Massey University, 2016) Mathurkar, Shashwati Chandrakant
Sheep suffer from pain during various husbandry practices as well as during injury or diseases such as footrot. This pain could be potentially minimised with the use of analgesics such as non-steroidal anti-inflammatory drugs (NSAID). Unfortunately, there are very few registered NSAIDs for sheep. Thus, registered analgesics for cattle, for instance ketoprofen and meloxicam are used in sheep. Again, the high cost of analgesics and associated potential side effects such as reduced fertility, gastric irritation, gastric ulcers etc. evident in other species usually limits their use in sheep. Fear of residues in meat may stop some farmers from using analgesics. Considering these problems, this study was designed as a groundwork to explore a possible and potential use of natural, inexpensive analgesic for sheep. Salicylic acid, a derivative of salicin, is a NSAID used effectively in humans as an analgesic since ancient times in the form of willow bark and leaves. During this research study, the pharmacokinetics of salicylic acid in sheep was analysed after administration of the sodium salt of salicylic acid (sodium salicylate/NaS) intravenously and orally at different dose rates. The analgesic efficacy of salicylic acid in sheep was also studied after administration of sodium salicylate at different dose rates by measuring mechanical and thermal nociceptive thresholds. The minimum therapeutic plasma concentration of salicylic acid for analgesia in sheep ranged from 25 to 30 μg/mL, which was achieved for about 30 minutes by a 200 mg/kg intravenous dose of NaS. During this study it was discovered that thermal nociceptive threshold testing is unable to detect any analgesia from salicylic acid and ketoprofen in sheep. However, mechanical nociceptive threshold testing efficiently detected the analgesic effects of salicylic acid and the positive control, ketoprofen. The seasonal variation of willow salicin content (principal precursor of salicylic acid in willow) was studied over a year. The salicin in willows in New Zealand is higher during the summer months as compared to the winter months of the year, and appears greater in areas subject to drought. The analgesic efficacy of willow leaves can be assessed by feeding the willow leaves to lame sheep as they readily eat willow leaves. However, to assess the analgesia produced by willow in sheep, further research is warranted. Keywords: Salicin, sheep, salicylic acid, analgesia, HPLC, nociceptive testing, willow.
Investigating the electrical response of the brain of the domestic chicken (Gallus gallus domesticus) to nociception through the use of depth electroencephalography (dEEG) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Physiology at Massey University, Manawatū, New Zealand
(Massey University, 2015) Trebilcock, Peter Dennis
Nociception is an unavoidable side effect of many routine management and clinical procedures in animals. Electroencephalography (EEG) has previously been used to investigate the effect of nociception on mammalian brain activity. This study aimed to develop a method of assessing the avian response to nociception through depth electroencephalography (dEEG) of brain regions believed to be involved in central pain processing. Two groups of chickens were used in this study to investigate two brain regions, the rostral hyperpallium apicale (HA) and the caudomedial nidopallium (NCM). These regions were chosen due to the afferent and efferent projections they receive from the sensory thalamus and their previous implication in pain processing. Subjects were anaesthetised, and a concentric needle electrode was inserted into the brain to record the electrical activity in response to a number of stimuli. These stimuli included one non-painful, somatosensory stimulus, and four nociceptive stimuli (mechanical, thermal, feather removal and electrical). The dEEG data was then run through a spectral analyser which generated the median frequency (F50), spectral edge frequency (F95) and total power (PTOT). Inspection of these variables determined that within the HA there were two populations of birds, therefore these birds were treated as separate groups in the analysis (hHA and lHA). It was seen that spectral characteristics of the three groups investigated differed significantly, indicating differences in activity and function. The response to stimulation was seen to be significantly different between these brain regions. Following stimulation, the hHA was seen to have a significantly lower percentage of baseline spectral edge frequency and median frequency compared to the NCM and lHA. In response to stimulation the activity of the NCM and lHA remained constant and showed no distinguishable response, while the hHA was more variable. The hHA was much more variable. Although there was no consistent response to stimulation, there was a significant decrease in total power following electrical stimulation in the hHA. This study presents a number of interesting findings and demonstrates that different regions of the brain respond in differing ways to stimulation. The findings suggest that the hyperpallium apicale may respond to nociceptive stimulation, however further work is required to distinguish this. The presence of two populations within the HA group suggests that recordings were taken from two distinct brain regions, one of which displayed comparatively higher sensitivity to nociceptive stimulation. Elucidation of this brain region and further research into the response to nociception is required to further understand the response of the avian brain to pain. For future studies, the development of more precise methods will be required to enable more accurate recording of the activity occurring throughout the avian brain.
The effect of early post-natal castration on subsequent electroencephalogram response to tail docking in lambs : a thesis presented in fulfilment of the requirements of the degree of Master of Veterinary Science at Massey University, Palmerston North, New Zealand
(Massey University, 2015) Impey, Steven
The objective of this study was to investigate the effect of early age painful stimulation on the cortical response to subsequent painful stimulation in lambs. Using the electroencephalogram (EEG), the current study measured the effect of early age castration at one day of age on the cortical pain response to tail docking at 23 days of age in lambs. Lambs were randomly assigned to rubber ring castration (n=12) or handling (n=12) at one day of age. At 23 days of age lambs were tail docked under a minimal plane of anaesthesia maintained using halothane in oxygen (PEHal = 1%). EEG data was recorded for two minutes pre-docking, and for eight minutes following tail docking. EEG median frequency, spectral edge frequency and total power were derived using fast Fourier transform. Data were analysed for group (castrated versus handled), time and group by time effects using mixed model analysis, as well as for the effect of group on pre-docking EEG. Castrated lambs showed an increased cortical response to pain, demonstrated by a greater increase in EEG median frequency (Mixed model analysis; F = 5.45, P = 0.03) and greater reduction in total power (F = 5.15, P = 0.03) in response to subsequent tail docking. These findings indicate that early age noxious stimulation results in an increased cortical response to subsequent noxious stimulation at approximately three weeks of age in lambs. The greater cortical response in the castrated lambs would likely correspond to an increased perception of pain, and therefore the potential for a greater degree of suffering and welfare compromise in response to subsequent painful injuries, for example lambing, injury and footrot. There was also a tendency toward a higher pre-docking total power of the EEG in the castrated lambs when compared with handled lambs (Satterthwaite’s t-test; T = 1.86, P = 0.08). The higher pre-docking total power may indicate a greater background activity in the nociceptive centres of the castrated lambs. However, the significance of this finding is not clear at this stage, and further work is necessary to better define the basis and clinical importance of this observation.
Alleviation of the distress caused by ring castration plus tailing of lambs and dehorning of calves : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Physiology at Massey University
(Massey University, 1999) Sutherland, Mhàiri Anne
There is increasing social and economic pressure to improve the welfare of animals in our care. In the present study plasma cortisol concentrations were measured to assess the pain-induced distress caused by ring castration plus tailing in lambs and dehorning in calves and the extent to which the distress caused by these procedures can be reduced by using different alleviation strategies. Local anaesthetic injected into the neck of the scrotum just before ring application significantly reduced the cortisol response to ring castration plus tailing in lambs, but local anaesthetic injected into the testes just after ring application only marginally reduced this response. A castration clamp was applied across the full width of the scrotum of lambs for 6 or 10 seconds after ring castration plus tailing to disable the innervation from the scrotal area. The application of the castration clamp for 6 seconds after placement of the ring did not reduce the cortisol response to ring castration plus tailing, whereas application for 10 seconds slightly, but significantly, reduced the peak cortisol concentration. Healing of the castration wound was not complicated by the application of the castration clamp after ring castration plus tailing. Therefore injecting local anaesthetic into the neck of the scrotum just before ring castration plus tailing significantly alleviates the pain-induced distress associated with ring castration plus tailing, but applying the castration clamp in combination with ring castration plus tailing has little benefit. Local anaesthetic given prior to dehorning virtually abolishes the cortisol response to dehorning for the duration of action of the local anaesthetic, but once the local anaesthetic wears off cortisol concentrations increase resulting in a delayed cortisol response equivalent to the overall cortisol response to dehorning when local anaesthetic is not used. This delayed cortisol response is thought to be stimulated by inflammation-related pain. The non-steroidal anti-inflammatory drugs (NSAIDs) ketoprofen and phenylbutazone and an endogenous cortisol surge stimulated by iniecting ACTH were used to assess whether this delayed cortisol response is associated with inflammation-related pain. Local anaesthetic (5 hour duration of action) plus ketoprofen given prior to scoop dehorning marginally reduced the delayed cortisol response observed once the local anaesthetic wore off, but giving local anaesthetic and phenylbutazone prior to dehorning had no significant effect on this delayed cortisol response. The antinociceptive action and a greater anti-inflammatory potency of ketoprofen compared to phenylbutazone may explain why ketoprofen was more effective than phenylbutazone in reducing this delayed cortisol response. ACTH plus local anaesthetic given prior to dehorning only marginally reduced the delayed cortisol response observed once the local anaesthetic wore off, suggesting that the delayed cortisol response seen when the local anaesthetic wears off is not due primarily to inflammation-related pain Giving local anaesthetic prior to dehorning and cauterising the amputation wounds prevented the delayed cortisol response after the local anaesthetic wore off and significantly reduced the overall cortisol response to dehorning. Thus, in the present study long acting local anaesthetic (5 hour duration of action) in combination with NSAIDs had minimal alleviating effects on the pain-induced distress caused by dehorning compared to local anaesthetic alone, but local anaesthetic and cautery provided effective pain-relief.
The use of thermal nociceptive threshold testing to assess the effect of analgesic drugs on the pain response of dairy cattle : a thesis presented in partial fulfilment of the requirements for the degree of Master of Veterinary Science in Veterinary Clinical Sciences at Massey University, Palmerston North, New Zealand
(Massey University, 2012) Barrett, Lorelle Anne
Painful procedures are routinely performed on cattle and the use of analgesia can abate this pain. Thermal nociceptive threshold (TNT) testing is used to assess pain sensitivity and the effect that painful conditions and analgesia have on this. However, little work has used TNT testing in cattle for these purposes. This research was carried out to determine if TNT testing could be used to assess the effects of analgesic drugs in both pain-free cattle and those that had undergone liver biopsy. A carbon dioxide laser was used as the noxious thermal stimulus. In the first experiment, the effects of an alpha2-adrenoreceptor agonist (medetomidine) and a non-steroidal anti-inflammatory drug (ketoprofen) were compared with the effect of saline on TNTs of pain-free cattle. TNTs were measured 20 minutes before treatments were administered, then again at 20, 40 and 60 minutes after treatment. Medetomidine significantly increased the cows’ TNT at 60 minutes post-treatment. This increased TNT may be due to the central analgesic properties of the drug. Ketoprofen had no effect on TNTs. In the second experiment, TNTs were measured to determine if different analgesic protocols moderated central sensitisation that may have occurred after liver biopsy. Behavioural observations were also used to assess pain in the post-biopsy period. Cows were assigned into one of four groups: control (local anaesthetic (LA) + sham-biopsy); LA + biopsy; LA + ketoprofen + biopsy; LA + meloxicam + biopsy. TNTs were measured 1 day before liver biopsy was performed, and once daily on the 3 days post-biopsy. Behavioural observations were made in the 4 hours after biopsy and on the 3 days post-biopsy. TNTs of biopsied cows did not differ from sham-biopsy cows. This may be because liver biopsy did not induce central sensitisation, or because the TNT method used did not reflect localised hyperalgesia. Behaviour also did not differ between treatment groups. These findings suggest that liver biopsy as it was performed here does not induce significant pain in cattle. It is concluded that TNT testing may be useful to investigate the effects of some analgesics on the acute pain response of pain-free cattle, but it has not been useful in demonstrating central sensitisation after liver biopsy. Further development and refinement of the methodology is required in order for this technique to be of future use for similar research in cattle.
Pain-induced distress and its alleviation using butorphanol after ovariohysterectomy of bitches : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Clinical Science at Massey University
(Massey University, 1995) Fox, Steven M.
Ovariohysterectomy is the most frequently performed surgical procedure in companion animal veterinary practice. It is regarded by many as being quite benign; however, questioning of that premise prompted this investigation. There were no satisfactory data available to determine how benign or noxious this procedure might be, yet this query is of considerable clinical importance. There exists the further vagary of assessment for pain-relief measures, whether associated with surgery or injury. Great value would lie in establishing a routinely available criterion for pain assessment. The present work was therefore undertaken to examine this area of clinical relevance and to establish a model for further study of postsurgical pain-induced distress and its alleviation. Most previous studies in this area had omitted Satisfactory control or baseline animals in that the anaesthetic or analgesic treatments were rarely, if ever, applied to animals that were not also subjected to surgery. Accordingly, the following nine treatments were made: Control, Anaesthesia, Analgesia, Analgesia plus Anaesthesia, Anaesthesia plus Analgesia at intubation, Anaesthesia plus Analgesia at extubation, Anaesthesia plus Surgery, Analgesia plus Anaesthesia plus Surgery, and Anaesthesia plus Surgery plus Analgesia. These were designed so that, with the inclusion of surgery, all the major variations in treatment were independently examined. The parameters used to evaluate the extent of pain-induced distress were changes in plasma cortisol concentration and behaviour. Cortisol is a well established physiological parameter of distress, and behaviour is a cue used by most clinicians. Butorphanol was selected as the analgesic of choice in this investigation based upon its wide use, margin of safety, across-species efficacy, versatility in route of administration, long shelf-life, competitive pricing, and freedom from the requirement for documented use by controlling authorities. The following conclusions were drawn from the cortisol data. Psychogenic stimuli in conscious control bitches were responsible for a transient rise in Cortisol concentrations not seen in anaesthetised dogs which were unconscious. Butorphanol elicited a large cortisol response, attributable to dysphoria, which was again prevented by anaesthetic administration. As judged by cortisol response there was no apparent benefit of preoperative butorphanol administered intravenously 30 minutes prior to or at the time of anaesthetic induction. However, there was an earlier decline in cortisol concentration when butorphanol was given at extubation and this was interpreted to reflect an earlier decrease in postoperative pain-induced distress. The study commenced with 166 behavioural parameters (interactive and noninteractive) from which it was found that 76 occurred at insufficient frequencies as to be valuable as indices of postoperative pain-induced distress. Among the discriminating behaviours, noninteractive parameters characteristic of the nonanalgesic surgery group were drawing the rear limbs up into a pike position, lip licking, cage circling, incision licking, vomition, and 'look back' (flank gazing), while the only characteristic interactive behaviour was an extended neck. Vocalisation was associated with the dysphoria of analgesia rather than pain-induced distress. The major contributions of this research were: (1) establishing ovariohysterectomy as a model of pain-induced distress to examine the benefit of various pain-control strategies, (2) elimination of a number of commonly seen behaviours and identification of useful behaviours for identifying pain-induced distress, (3) clarification of the responses to control and 'base-comparison' treatments with regard to both cortisol and behavioural responses, (4) identification of specific pain-induced behaviours, (5) derivation of a mathematical function representing a numerical expression for the clinical intuition of the subjective impression of pain experience in dogs, and (6) identifying behaviours that can be used by the clinician to indicate the presence or absence of pain-induced distress following ovariohysterectomy. Results suggest that the ovariohysterectomy is associated with sufficient pain-induced distress to warrant the associated use of analgesia.
The effect of early painful experiences on subsequent pain sensitivity in lambs : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Physiology at Massey University, Manawatu, New Zealand
(Massey University, 2011) Pifeliti, Seini
There is evidence that painful events in early life can alter subsequent pain processing and sensitivity, at least in altricial species. However, it is not known whether similar effects occur in precocial species, such as lambs, which are relatively mature at birth. Lambs in New Zealand are routinely exposed to painful procedures like castration and tail docking at a young age. The possibility that these early procedures result in hypersensitivity to subsequent painful events is a serious welfare issue. The aim of this study was to assess the effect of early castration on the behavioural responses of lambs to subsequent tail docking. The effect of age at first treatment (castration or control handling) and age at docking were also assessed. Lambs were castrated (C) or handled (H) at either 1 (Group 1, N=21; Group 2, N=27; Group 3, N=23; Group 4, N=24) or 21 (Group 5, N=26; Group 6, N=24) days of age and their behavioural responses to docking measured 3-6 weeks later. Differences between C and H lambs were evident before docking had taken place; C lambs walked backwards less frequently and spent less time standing unsteadily than H lambs. After docking, C lambs stamped their feet more frequently and spent less time lying laterally than H lambs. Age at first treatment was not found to have a significant effect on behaviour in response to docking. Interestingly, lambs docked at 42 days of age differed from those docked at 21 days of age in their response. Twenty-one-day old lambs displayed significantly higher frequencies and durations of a number of pain-related behaviours when compared to their 42 day old counterparts. Only one behaviour, unsteady standing, was performed for longer durations by the older lambs. It can be concluded that castration does affect the behavioural response of lambs to subsequent docking and that age at docking is also a significant factor in this response. Further research is required to further clarify the magnitude of these effects.
Neurological development and the potential for conscious perception after birth : comparison between species and implications for animal welfare : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Physiology, Massey University, Palmerston North, New Zealand
(Massey University, 2010) Diesch, Tamara Johanna
In order for animals to experience pain and to suffer from it, they have to be capable of conscious perception. Recent evidence suggests that the fetus is maintained in a sleeplike unconscious state and that conscious perception therefore only occurs after birth. The timing of the onset of conscious perception depends on the maturation of underlying neurological processes and is anticipated to be species dependent. Painspecific electroencephalographic (EEG) responses of lightly anaesthetised young of three species born at different levels of neurological development were investigated. The results of the present thesis are in agreement with published data on general neurological, EEG and behavioural development. This information, in addition to the present results, has been used to estimate the approximate time of the onset of conscious perception in tammar wallaby joeys, rat pups and newborn lambs. In wallaby joeys (extremely immature at birth), the EEG remained isoelectric until about 100-120 days of in-pouch age and became continuous by about 150-160 days, with electroencephalographic and behavioural signs of conscious perception apparent by about 160-180 days. In rat pups (immature at birth), the absence of a differentiated EEG suggests that the ability for conscious perception in pups younger than 10-12 days is doubtful. The marginal EEG responses to noxious stimulation in 12-14 day-old pups and the pronounced EEG responses in pups 18-20 days suggest that rats may be capable of conscious perception from 12-14 days onwards. In lambs (mature at birth), full conscious perception is probably not apparent before 5 minutes after birth and may take up to several hours or days to become fully established. Its modulation by the residual neuroinhibitor allopregnanolone, if that occurs, would be highest over the first 12 hours after birth. Overall, the onset of conscious perception does not seem to follow an “on-off phenomenon”, but seems to develop gradually, even in species born neurologically mature. Although conscious perception, and hence pain experience, may be qualitatively different in younger animals, on the basis of the precautionary principle, when significantly invasive procedures are planned, pain relief should be provided from those postnatal ages when pain may first be perceived – i.e. from about 120 days in the tammar wallaby joey, about 10 days in the rat pup and from soon after birth in the lamb.
Electroencephalographic responses of calves to the noxious sensory input of slaughter by ventral neck incision and its modulation with non-penetrative captive bolt stunning : a thesis presented in partial fulfilment of the requirements of the degree of Doctor of Philosophy in Physiology, Massey University, Palmerston North, New Zealand
(Massey University, 2009) Gibson, Troy John
Slaughter by ventral neck incision (VNI) is performed on some animals without prior stunning in New Zealand and other countries. A single incision with a razor sharp blade is made in the ventral aspect of the neck, sectioning both carotid arteries and jugular veins, though, not the vertebral arteries. There are a number of potential welfare concerns surrounding slaughter by VNI including pain due to the incision, which may lead to distress during the time before loss of consciousness. The aims of this thesis were to identify cortical responses indicative of noxious stimulation due to slaughter by VNI using analysis of the electroencephalogram (EEG) power spectrum and to investigate the effects of non-penetrative captive bolt (NPCB) stunning on these cortical responses. The studies utilised adaptations of a minimal anaesthesia model, which has been validated in a range of mammalian species. Surgical dehorning was used as a validation technique for this methodology in cattle and demonstrated a ‘typical’ EEG response to noxious stimulation. Cattle slaughtered by VNI without prior stunning produced specific responses in the EEG that strongly indicated responses to noxious stimulation. Causation was investigated in cattle where blood flow through the brain remained intact during neck tissue incision (NTI) or the major blood vessels of the neck were isolated and transected independently of other neck tissues (BVT). The response to neck incision in intact animals was principally due to the noxious sensory input due to incision of neck tissues and not mainly as a result of loss of blood flow through the brain. NPCB stunning produced states of cortical activity that were incompatible with the maintenance of sensibility and pain perception. Experimental examination of the time to onset of undoubted insensibility was attempted in cattle subsequent to a pilot study in sheep. The generation of somatosensory-evoked potentials was problematic in cattle. The conclusions of this thesis are that incision of neck tissues during slaughter without prior stunning constitutes a substantial noxious stimulus. Were an animal conscious, this stimulus would be perceived as painful until the onset of hypoxiainduced insensibility. This would represent a significant compromise to animal welfare.

Massey Documents by Type

Browse

Filters

Settings

Sort By

Results per page

Search Results