Quantification of the pain and distress responses to castration in young lambs

Pain and distress following castration were assessed in lambs using three indicators: behaviour, plasma cortisol and mechanical nociceptive thresholds. Three castration methods: rubber ring (RR), combined ring and Burdizzo clamp (CM) and surgery (SU) were compared. The effects of castration following local anaesthetic pre-treatment (LA) and castration performed under general anaesthetic (GA) were compared to castration performed with no anaesthetic. This gave a 4 x 3 x 3 block design i.e. 36 experimental treatments. Six lambs were allocated to each treatment i.e. 216 lambs were used in all. SU produced the greatest response, followed by RR then CM castration. LA abolished the responses to RR and CM castration but had no effect on the response to SU castration. GA did not reduce the responses to RR and SU but abolished the rise in mechanical nociceptive thresholds and markedly attenuated active pain behaviours in lambs CM castrated without anaesthesia. This suggests that the clamping procedure itself rather than post-castration pain and distress is responsible for the rise in nociceptive thresholds and active pain behaviours in CM castrated lambs.     

Influence of local anaesthesia on pain and distress induced by bloodless castration methods in young lambs

Behavioural and cortisol responses of lambs were used as indicators of pain and distress to assess short- and long-term effects of bloodless castration methods with and without local anaesthesia. Eighty lambs, aged 2-7 days, were control handled or castrated by crushing- Burdizzo- or rubber ring method with and without local anaesthesia. Either 4 mg/kg diluted lidocaine, or corresponding volumes of physiologic sodium chloride solution were distributed in both spermatic cords and the scrotal neck. The serum cortisol response was monitored for 48 h, behavioural- and clinical traits over a 3-month period. The crushing castration method was excluded from the study after 10 lambs had been castrated, since this method showed severe local reactions. Local anaesthesia significantly reduced behavioural and cortisol responses after rubber ring castration and tendentially after Burdizzo castration. Prolonged or chronic pain after rubber ring castration with anaesthesia was not evident. If combined with local anaesthesia, both the rubber ring and the Burdizzo method are acceptable methods for castration of lambs up to one week of age.     

Castration of lambs: a welfare comparison of different castration techniques in lambs over 10 weeks of age

Seventy male lambs over 10 weeks of age were castrated using Burdizzo, rubber rings, or surgery to assess the acute and long-term effects of castration. All castrations were performed under local anaesthesia. The surgically castrated lambs were additionally sedated with xylazine and the sedation reversed with tolazoline. The frequency of abnormal postures and immediate behavioural responses indicated that surgically castrated lambs were most distressed; the lambs castrated using Burdizzo and rubber rings were not dissimilar to those of the control group. Between 1.5 and 9 h after castration, signs of pain and distress were at a lower level in lambs anaesthetised with bupivacaine compared with those treated with lidocaine. Due to the markedly faster wound healing, Burdizzo castration seemed to be preferable (fewer signs of long-term pain) when compared to the rubber ring technique. It was concluded that local anaesthesia with bupivacaine, followed by the Burdizzo method is the preferable technique for the castration of lambs older than 10 weeks of age.     

Influence of local anaesthesia on pain and distress induced by two bloodless castration methods in young lambs

To assess short- and long-term effects of bloodless castration methods with and without local anaesthesia, behavioural and cortisol responses of lambs were used as indicators of pain and distress. Seventy lambs, aged 2-7 days, were control-handled or castrated by Burdizzo or rubber ring methods with and without local anaesthesia. Either 5 mL of diluted lidocaine (4 mg/kg) or physiological sodium chloride solution was distributed in both spermatic cords and the scrotal neck. The serum cortisol response was monitored for 48 h, and behavioural and clinical traits were followed for three months. Local anaesthesia tended to reduce behavioural and cortisol responses after Burdizzo castration and provided a significant reduction after rubber ring castration. Prolonged pain after rubber ring castration with anaesthesia was not evident. If combined with local anaesthesia, both the rubber ring and the Burdizzo methods are acceptable methods for castration of lambs up to one week of age.     

Randomised, controlled field trial of two new techniques for the castration and tail docking of lambs less than two days of age

Two methods to reduce the pain associated with the castration and tail docking of lambs with rubber rings were tested by 10 shepherds, each using 60 housed lambs. In 20 of the lambs the innervation to the scrotum, testes and tail was crushed with a 'Big Nipper' bloodless castrator, and in 20 local anaesthetic (2 per cent lignocaine with adrenaline) was injected with a newly developed high-pressure jet injector under the rubber rings after they had been applied; 10 lambs were given a placebo treatment and 10 were treated by the shepherds' routine elastrator ring procedure. Both new methods significantly decreased the incidence of limb and tail movement by 78 per cent and the time spent by the lambs in abnormal postures, when compared with either the shepherds' routine treatment or the placebo treatment. An experienced observer and most of the shepherds also assessed that the lambs suffered signficantly less pain when treated by the two new methods than when they were treated with rubber rings alone. No detrimental long-term effects of the two new methods were observed. On average the new methods took 68 seconds to apply, compared with 29 seconds for the rubber rings; of the two new methods most shepherds preferred using the pressure jet injector.     

Effects of local anesthesia and intravenous naloxone on the changes in behaviour and plasma concentrations of cortisol produced by castration and tail docking with tight rubber rings in young lambs.

The reliability of some behavioral and physiological indices used for the recognition and assessment of acute pain in lambs after castration and tail docking has been examined. Changes in the indices were measured after blocking neural activity with local anaesthetic (lignocaine) and after an opioid antagonist (naloxone) was administered. Six lambs, aged less than one week, were allocated randomly to each of six treatments. (i) control handling and blood sampling; (ii) castration plus tail docking with tight rubber rings; (iii) local anaesthesia; (iv) local anaesthesia followed by castration and tail docking; (v) intravenous naloxone only (0.2 mg kg-1); and (vi) intravenous naloxone followed by castration and tail docking. Local anaesthesia eliminated the behavioural and plasma cortisol changes which usually follow castration and tail docking. Naloxone had a limited effect on the increase in cortisol but altered the behaviour. The results support the view that such indices are useful for assessment of the response to acute pain and that, although endogenous opioids do reduce pain in young lambs after castration and tail docking, the effect is small.     

Topical anaesthesia alleviates short-term pain of castration and tail docking in lambs

Objective To investigate the effect of a topical anaesthetic formulation on pain alleviation, wound healing and systemic levels of local anaesthetic actives in lambs undergoing castration and tail docking. Design Three placebo-controlled and/or randomised experiments were conducted using three groups of Merino lambs (n = 62, 68 and 19) undergoing routine castration and tail docking. Procedure Surgical castration, with either surgical or hot-iron tail docking, was performed with and without the application of topical anaesthetic (Tri-Solfen®) or placebo. The effects of this procedure were compared with those of rubber ring castration and tail docking, and of the handled but unmarked controls. Wound pain was assessed using calibrated Von-Frey monofilaments over a 4-h period, pain-related behaviour was assessed over 5 h, wound healing was assessed at 14 and 28 days, and the plasma levels of lignocaine and bupivacaine were determined. Results Rapid and up to 4 h primary hyperalgesia developed following surgical castration and tail docking in the untreated and placebo-treated lambs. It was absent in the castration wounds, and significantly reduced in the tail-docking wounds, of the treated lambs. Hot-iron docking was associated with mild and transient secondary hyperalgesia, which was abolished by the topical anaesthesia. There was a significant reduction in pain-related behaviours in treated lambs, which were not significantly different in their behaviour to the sham-operation handled controls. Plasma lignocaine and bupivacaine levels were below the toxic thresholds in all tested lambs. Conclusion Topical anaesthesia alleviates wound pain and significantly reduces pain-related behaviours in lambs undergoing surgical castration plus surgical or hot-iron tail docking, without a negative effect on wound healing or a risk of systemic toxicity.     

Acute cortisol responses of lambs to castration using a rubber ring and/or a castration clamp with or without local anaesthetic

Changes in plasma cortisol concentrations during the first 4 hours after castration of 6-week-old lambs by one of four methods were measured. The methods were application of a rubber ring above the testes, application of a ring to shorten the scrotum below the testes, use of a castration clamp plus a ring, and use of a castration clamp alone. The efficacy of local anaesthetic in reducing or abolishing the cortisol responses to castration by all these methods except short scrotum was assessed. Local anaesthetic was injected into the neck of the scrotum, both spermatic cords, the scrotal neck plus spermatic cords, or into both testes. The combined clamp plus ring method was used to test whether or not clamp damage to afferent nerves from the testes would reduce the cortisol response to ring castration. The short scrotum method elicited a significantly lower cortisol response than that caused by ring castration. Injection of local anaesthetic into both spermatic cords marginally reduced the cortisol response to ring castration, but the response was virtually abolished by prior scrotal neck, or scrotal neck plus spermatic cords, or intra-testicular local anaesthetic injections. The clamp plus ring method, where each spermatic cord and the associated scrotal tissue were crushed separately for 1, 5 or 10 seconds with no overlap between the two crush lines, did not elicit lower cortisol responses than the ring-only method. Local anaesthetic injected into the scrotal neck virtually abolished, and spermatic cord injections markedly reduced, the cortisol responses to combined clamp plus ring castration. The IO-second clamp application caused a more protracted cortisol response than did ring-only castration, whereas the cortisol responses to 1-second clamp application and to ring-only castration were similar. Local anaesthetic injected into the scrotal neck or spermatic cords did not affect significantly the cortisol response to the IO-second clamp application. The following conclusions were drawn from this work: the testes as well as the scrotum were sources of noxious sensory input after ring application; the clamp plus ring method used here was ineffective in reducing the pain-induced distress (as indicated by cortisol concentrations) caused by ring-only castration; injection of local anaesthetic into the scrotal neck or into the testes prior to ring application blocked most noxious sensory input from both the scrotum and the testes; and on the basis of the present cortisol responses the 10-second clamp applications method could not be recommended in reference to the ring-only method, but the l-second clamp application method might be equally acceptable for castrating 6-week-old-lambs. Of the methods examined, injections of local anaesthetic into the scrotal neck or both testes were the most effective in reducing the pain-induced distress caused by ring-only castration.     

Acute castration and/or tailing distress and its alleviation in lambs

PURPOSES AND APPROACH: Acute castration and/or tailing distress in lambs has been examined extensively during the last decade. At least 59 different approaches to assessing and alleviating this distress have been reported so that the literature is quite complex. The purpose of this paper is to provide an overview of the literature on castration and/or tailing distress, where the distress was assessed using acute changes in plasma cortisol concentrations. A method of analysis involving the integrated cortisol response (i.e. the areas under the cortisol curves while the plasma concentration is above pretreatment values) to each treatment and using treatments which were common to different studies as reference points, allowed meaningful comparison within and between studies. A 6-point ranking scale emerged, where rank 1 represented the least distress and rank 6 the most distress. COMPARISON OF ACUTE DISTRESS RESPONSES: This analysis revealed the following major points. Surgical methods of castration and/or tailing cause the greatest cortisol responses (rank 5 or 6). Most ring and ring plus clamp methods of castration plus tailing or castration, used without a local anaesthetic or systemic analgesic, cause rank 4 responses. One form of ring plus clamp castration (i.e. applying the clamp for 10 s across the full width of the scrotum distal to the ring in lambs aged no more than 1 week) reduces the cortisol response to rank 1. When these lambs are also tailed by applying a ring and clamp in a similar manner to the tail, they also exhibit a rank 1 response. Local anaesthetic given 10-20 or 12 min or 10-15 s before or immediately after ring only castration and/or tailing can virtually abolish the cortisol response (rank 1), depending on the site(s) of injection. For ring or ring plus clamp castration, the most effective sites (as judged by cortisol responses) are the neck of the scrotum or the testes. Delivery of local anaesthetic to achieve successful nerve blockade can be by needle, high-pressure needleless administration or, for the tail only, by an aerosol spray. Local anaesthetic injected into the scrotal neck, spermatic cords and/or testes has little effect on the overall cortisol response to clamp castration. Reductions in cortisol responses to clamp castration or to ring tailing can occur after administration of non-steroidal anti-inflammatory drugs. Most tailing methods elicit cortisol responses that are several ranks lower than those caused by castration plus tailing or castration alone. Although tailing by most methods elicits rank 1 cortisol responses, the use of local anaesthetic or non-steroidal anti-inflammatory drugs can reduce the response within the rank 1 range. RECOMMENDATION: Farmers should be encouraged to choose the lowest ranked method that is economically and practically feasible for them. Specific methods such as surgical castration should be discouraged.     

Effects of acute pain reduction methods on the chronic inflammatory lesions and behaviour of lambs castrated and tail docked with rubber rings at less than two days of age

Lesions were produced by castration and tail docking of two-day-old Dorset-cross lambs with elastrator rings with (RRla) and without (RR) local anaesthetic or after destruction of the innervation by crushing close to the ring (Brr). The lesions were monitored twice weekly for six weeks and the behaviour of handled controls (H), RR and RRla lambs was recorded for two 3 h periods 10, 20, 31 and 41 days after treatment. There was no significant effect of castration and tail docking, with or without pain reduction methods, on daily liveweight gain. In the Brr lambs, the dead tails were cast 10 days earlier than from RR and RRla lambs. The time taken for the scrotal lesion to reach maximum severity was halved in Brr and RRla lambs, although the maximum severity of the lesion was unaffected by the methods of pain reduction. During the four 6 h behavioural observation periods, RR lambs showed a significant increase in the mean (+/- sd) frequency of foot stamping (RR13 +/- 13; H2 +/- 2.5), tail wagging (61 +/- 26; 15 +/- 6), head turning to the scrotum and inside hind-leg (12 +/- 10; 1 +/- 1). Less abnormal behaviour was found after RRla than after RR treatment. This unexpected finding may be evidence of long-lasting increases in pain sensitivity after an episode of intense acute pain in young animals.     

Effects of a topical anaesthetic formulation and systemic carprofen, given singly or in combination, on the cortisol and behavioural responses of Merino lambs to castration

Objective   To determine the effectiveness of a topical anaesthetic formulation (Tri-Solfen) with or without the administration of a non-steroidal anti-inflammatory drug (carprofen) on the pain and distress response associated with ring or surgical castration of ram lambs.
Procedures   Merino ram lambs (n = 78) were allocated to 10 treatment groups: 4 groups of knife-castrated lambs and 4 groups of ring-castrated lambs received carprofen (4 mg/kg SC) and Tri-Solfen; 2 control groups (sham) received carprofen at 0 or 4 mg/kg SC. Measurements included plasma cortisol and haptoglobin concentrations, haematology, and behaviour, including posture.
Results   Knife-castrated lambs had higher peak cortisol and integrated cortisol responses for the first 6 h after treatment and greater concentration s of circulating acute phase proteins than ring-castrated lambs, both of which were significantly different from the sham controls. Tri-Solfen applied to the knife castration wound significantly reduced both the peak plasma cortisol concentration and the integrated cortisol response for the first 6 h and improved lying behaviour in the first 12 h. Carprofen reduced the cortisol response to knife castration at 30 min, but elevated the cortisol responses at 24 and 48 h. Carprofen nearly halved the number of acute pain behaviours associated with ring castration. There were no significant additive or synergistic effects from combining the analgesic treatments. Tri-Solfen applied to the tail wound provided no detectible benefits during ring castration + tail docking.
Conclusions   The physiological and behavioural responses suggest that ring castration has less impact on the lamb than knife castration. The specific analgesic treatments can provide modest amelioration of the pain and discomfort associated with castration. Alternative doses or application methods may enhance their efficacy.     

Afferent activity in the superior spermatic nerve of lambs — The effects of application of rubber castration rings

Electrophysiological techniques were used to record afferent activity in the superior spermatic nerves of young lambs under general anaesthesia. Receptive fields were identified in the pampiniform plexus and the deep tissue of the testis in response to mechanical stimulation. Application of a standard rubber castration ring to the scrotal neck evoked vigorous afferent activity, including some from formerly silent units with receptive fields particularly in the pampiniform plexus. Some of this multi-unit discharge adapted rapidly within 10 s of the application of the ring and was followed by a discharge pattern which decayed exponentially over 90 min. The rate of decay of this discharge showed more than one exponent (time constant) with inflections at approximately 90 s and 16 min. After the application of the castration ring, quantitatively controlled scrotal compression continued to excite receptors, though a declining frequency was recorded over the period of observation. It was concluded that: (a) rubber castration rings initiated afferent activity which persisted for periods in excess of 90 min, a time course which is similar to the behavioural and humoral changes in the conscious animal; (b) both standard and small rubber castration rings were ineffective in rapidly producing neuronal pressure block of the slowly conducting afferent fibres in the superior spermatic nerve; (c) intra-testicular injection of local anaesthetic rapidly blocked afferent fibres running in the superior spermatic nerve.Abbreviations TTL transistor transistor logic     

A comparison of catecholamine and cortisol responses of young lambs and calves to painful husbandry procedures

AIM: To compare the changes in plasma concentrations of noradrenaline, adrenaline and cortisol in lambs after ring castration plus tailing and in calves after dehorning with or without prior local anaesthesia. METHODS: Male lambs were castrated and tailed with rings and calves were dehorned by amputation using a scoop with or without prior local anaesthesia. Blood samples were taken before and after treatment and plasma concentrations of noradrenaline, adrenaline and cortisol were determined. RESULTS: Castration plus tailing of lambs resulted in a rapid increase in noradrenaline concentrations, a lack of an adrenaline response and a marked increase in cortisol concentration. There were similar changes in catecholamine concentrations in calves that were dehorned both with and without local anaesthetic, with adrenaline being elevated within 5 min of treatment and noradrenaline exhibiting a more protracted response. Dehorning caused a marked cortisol increase which was reduced to control concentrations by local anaesthesia for as long as the associated nerve blockade lasted. CONCLUSIONS: The very short-lived adrenaline responses in calves were attributed to dehorning-induced nociceptor input leading to sympathetic stimulation of the adrenal medulla. The longer lasting noradrenaline responses in lambs and calves were thought be due to 'wash-out' of noradrenaline from damaged tissue associated with rings and amputation wounds, respectively.     

Stress responses in lambs docked and castrated surgically or by the application of rubber rings

A comparative study has been made in lambs 3 to 6 weeks of age of the behavioural responses and changes in plasma immunoreactive beta-endorphin (ir beta-endorphin) and cortisol after docking or docking plus castration by the application of rubber rings or by surgery. The use of rubber rings on lambs at this age was characterised by very agitated behaviour indicative of considerable distress for a period of up to 1 h. In contrast, surgery was accompanied by some post-operative shock exhibited by reduced exploratory and social behaviour, at least in the lambs exposed to docking plus castration. In the latter group there were highly significant increases in both plasma ir beta-endorphin and cortisol concentrations that may be consistent with the induction of stress-induced analgesia. We conclude that surgery caused less distress than the rubber rings, and is therefore preferable for docking and castration of lambs 3 to 6 weeks of age.     

Cortisol responses of young lambs to castration and tailing using different methods

Lambs at 4-5 weeks of age were studied during the first 4 hours after castration and/or tailing using three methods in various commonly used combinations. The methods were cutting with a knife, application of constricting rubber rings and using a heated docking iron (tailing only). The integrated cortisol response (area under the cortisol curve) was determined for each lamb during the first 4 hours after treatment and was considered to reflect the overall magnitude of the lamb's acute distress response. On that basis, cut lambs (tailing only, castration only, castration plus tailing) experienced more distress than any other groups. Also the distress response (indicated by elevated plasma cortisol concentrations) lasted longer than 4 hours in cut lambs, unlike all other groups. The use of rings apparently caused similar distress when lambs were castrated only, were castrated plus tailed, or were short-scrotumed (testes pressed against the abdominal wall by a distally located scrotal ring) plus tailed. The magnitudes of distress apparently caused by tailing alone with a ring or a docking iron were similar and were lower than the distress caused by any other castration and/or tailing procedure. It is concluded that acute distress responses to these husbandry procedures would be minimised in lambs of this age if rings and/or a docking iron were used in preference to a knife.     

Blood pressure, heart rate, hormonal and other acute responses to rubber-ring castration and tail docking of lambs

AIM: To examine cardiovascular, hormonal and other physiological responses of 2-month-old lambs to rubber-ring castration and tail docking. METHODS: Twenty-two male lambs, well accustomed to handling and prepared with femoral artery and jugular vein cannulae, were studied during a 5 h control period and, at least 2 days later, for 1 h before and 4 h after castration and tail docking using rubber rings. Pressure recordings were made via femoral cannulae and blood samples for analysis of plasma constituents were taken from jugular cannulae. RESULTS: Mean systolic, diastolic and mean arterial blood pressure, heart rate and the plasma concentrations of adrenocorticotropic hormone (ACTH) and cortisol all increased markedly during the first 1 h after ring castration and tail docking. Although plasma ACTH and cortisol concentrations had returned to control levels by 2.5-3 h, blood pressures and heart rate were still elevated 4 h after ring application. In contrast, there were no significant changes in mean plasma concentrations of renin, electrolytes, minerals, glucose, lactate, urea, creatinine, total carbon dioxide and total proteins, plasma osmolality or the haematocrit after ring application. There were no significant changes in the mean values for any parameter during the 5 h control period or the 1 h period before ring application. CONCLUSION: Systolic, diastolic and mean arterial blood pressure and heart rate may be more sensitive than plasma ACTH or cortisol concentrations as indices of low-grade pain induced by ring castration and tail docking. Alternatively, it is possible that by 4 h after ring placement a small shift in sympathetic tone still persists in the absence of low-grade pain.     

Salmonella newington in chickens in New Zealand

Lambs at 4–5 weeks of age were studied during the first 4 hours after castration and/or tailing using three methods in various commonly used combinations. The methods were cutting with a knife, application of constricting rubber rings and using a heated docking iron (tailing only). The integrated cortisol response (area under the cortisol curve) was determined for each lamb during the first 4 hours after treatment and was considered to reflect the overall magnitude of the lamb's acute distress response. On that basis, cut lambs (tailing only, castration only, castration plus tailing) experienced more distress than any other groups. Also the distress response (indicated by elevated plasma cortisol concentrations) lasted longer than 4 hours in cut lambs, unlike all other groups. The use of rings apparently caused similar distress when lambs were castrated only, were castrated plus tailed, or were short-scrotumed (testes pressed against the abdominal wall by a distally located scrotal ring) plus tailed. The magnitudes of distress apparently caused by tailing alone with a ring or a docking iron were similar and were lower than the distress caused by any other castration and/or tailing procedure. It is concluded that acute distress responses to these husbandry procedures would be minimised in lambs of this age if rings and/or a docking iron were used in preference to a knife.     

Influence of local anaesthesia on short- and long-term pain induced in calves by three bloodless castration methods

Behavioural and cortisol responses of calves were used as indicators of pain to assess short- and long-term effects of three bloodless castration methods with and without local anaesthesia. Eighty calves, aged 21 to 28 days, were control handled (20) or castrated by Burdizzo (25), rubber ring (25), or crushing technique (10). Either a total volume of 10 ml of Lidocaine or NaCl was distributed in both spermatic cords and the scrotal neck. The plasma cortisol response was monitored for 72 hours, and behavioural and clinical traits over a three-month period. Castration success was assessed by degree of atrophy and histological tissue examination. The crushing technique cannot be recommended due to incomplete castration success, and the evaluation was stopped after 10 animals. Local anaesthesia reduced the level of indicators of acute pain after Burdizzo and rubber ring technique. It did, however, not result in a totally painless castration. When castration is performed at the age of 3 to 4 weeks, the rubber ring but not the Burdizzo method showed evidence of chronic pain lasting for several weeks.     

Effects of castration on behaviour and plasma cortisol concentrations in young lambs, kids and calves.

Behavioural and cortisol responses to the husbandry practice of castration with tight rubber rings were investigated in lambs and kids one day after birth and in hand reared calves aged one to seven days. There were three treatments: control handling and blood sampling, castration and, in lambs and kids only, intravenous adrenocorticotrophin injection (ACTH). The integrated cortisol responses (area under the cortisol curve) in lambs and kids were least in control, intermediate in castrated and greatest in ACTH animals. No cortisol responses were detected in control or castrated calves. The incidences of behaviour used to assess the intensity of distress apparently experienced in the different species corresponded generally with the magnitudes of the cortisol responses. Behavioural and cortisol responses together suggested that the distress caused by castration was greatest in lambs, intermediate in kids and least but not necessarily absent in hand reared calves.     

Effect of local anaesthesia on short- and long-term pain induced by two bloodless castration methods in calves

Behavioural and cortisol responses of calves were used as indicators of pain to assess short- and long-term effects of bloodless castration methods with and without local anaesthesia. Seventy calves, aged 21-28 days, were control handled (20) or castrated using the Burdizzo (25) or rubber ring technique (25). Either 10 mL lidocaine or NaCl were distributed in both spermatic cords and the scrotal neck. The plasma cortisol response was recorded for 72 h, and behavioural and clinical traits monitored over a three month period. Local anaesthesia reduced the level of indicators of acute pain after both the Burdizzo and rubber ring techniques. It did not, however, result in a totally painless castration. As there was evidence of chronic pain lasting for several weeks after rubber ring castration, the Burdizzo method is judged to be preferable to the rubber ring technique.