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.     

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.     

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.     

Pain in lambs castrated at 2 days using novel smaller and tighter rubber rings without and with local anaesthetic

Without effective pain relief, rubber ring castration of lambs is acutely painful and can also produce chronic pain. The potential of novel, smaller rubber rings to reduce this pain substantially has been investigated. Three groups of eight 2-3 day old lambs, were castrated either with conventional rubber rings (cRR), or novel smaller rubber rings without (nRR) and with local anaesthetic treatment (nRR+La). Behavioural responses and chronic lesions indicative of pain were compared. No major reductions in behavioural responses were produced by castration with nRRs compared with cRRs, but injection of local anaesthetic did reduce these responses significantly. Lambs in all groups developed chronic inflammatory lesions but behavioural evidence of chronic pain was rarely seen. After 28 days, 6/8 necrotic scrotums had been shed by nRR+La; 4/8 by nRR and 2/8 by cRR lambs. The dimensions of rubber rings on necrotic scrotums, suggest that cRRs contracted to their un-stretched size before being shed, whereas nRRs did not. It is concluded that neither of these rubber rings exerted sufficient pressure on trapped nerves to produce anaesthesia rapidly and this may be explained by the physical properties of the tissues at the neck of the scrotum which support the ring.     

Effects of early human handling on the pain sensitivity of young lambs

Objective Pain sensitivity of lambs changes over the first weeks of life. However, the effects of early treatments such as human handling on pain sensitivity are unknown for this species. This study investigated the effects of regular early gentle human handling on the pain sensitivity of lambs, indicated by their behavioural responses to tail docking. Study design Prospective part‐blinded experimental study. Animals Twenty‐nine singleton Coopworth lambs (females n = 14, males n = 15). Methods Starting at one day of age, lambs were either handled twice daily for 2 weeks (Handled), were kept in the presence of lambs who were being handled but were not handled themselves (Presence), or were exposed to a human only during routine feeding and care (Control). At 3 weeks of age, all lambs were tail docked using rubber rings. Changes in behaviour due to docking were calculated and change data were analyzed using two‐way anova with treatment and test pen as main factors. Results All lambs showed significant increases in the frequency and duration of behaviours indicative of pain, including ‘abnormal’ behaviours, and decreases in the frequency and duration of ‘normal’ behaviours after docking. Handled lambs showed a smaller increase in the time spent lying abnormally after docking than did Control lambs (mean transformed change in proportion of 30 minutes spent ± SE: Control 0.55 ± 0.04; Handled 0.38 ± 0.03; Presence 0.48 ± 0.03; C versus H t = 3.45, p = 0.007). Conclusions and clinical relevance These results provide some evidence that handling early in life may reduce subsequent pain sensitivity in lambs. While the behavioural effects of handling on pain behaviour were subtle, the results suggest, at the very least, that early handling does not increase pain sensitivity in lambs and suggests there is still flexibility postnatally in the pain processing system of a precocial species.     

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.     

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.     

Effect of age at castration on behavioural response to subsequent tail docking in lambs

Objective To investigate the effects of age at castration on the subsequent behavioural response to tail docking. Study design Randomised prospective blinded experimental study. Animals Forty‐five male lambs were admitted to the study at birth. Methods The lambs were allocated into two groups for castration by rubber ring at 1 (1D, n = 20) or 10 (10D, n = 25) days of age. Following castration both groups of lambs were tail‐docked by rubber ring at between 26 and 34 days of age. Their behavioural responses to tail docking were recorded by video for 30 minutes before (n = 11) and 30 minutes after (n = 45) tail docking. Statistical differences were tested using anova with Mann‐Whitney post‐hoc testing. Results Two data sets were removed resulting in n = 19 and = 24 at 1D and 10D, respectively. A significant increase in the incidence of active and abnormal postural behaviour was seen in both groups after tail docking. Three behaviours were significantly different (p < 0.05) between the two groups. These behaviours were rolling, standing unsteadily and the total proportion of time standing with abnormal posture. These behaviours all had greater incidence in the lambs castrated at 1D of age. Conclusions Lambs castrated at 1D appeared to perceive a greater intensity of pain after subsequent tail docking than lambs castrated at 10D. Clinical relevance The timing of a single noxious stimulus in young animals can affect subsequent pain perception.     

Impact of topical anaesthesia on pain alleviation and wound healing in lambs after mulesing

Objective     To investigate the impact of using the topical anaesthetic preparation Tri-Solfen® on pain alleviation and wound healing in lambs undergoing mulesing.
Design   Three separate trials, placebo controlled and/or randomised, were carried out over a 5 month period on three mobs of between 60 and 263 merino lambs undergoing routine mulesing.
Procedure     Wound pain was assessed using 10 and 75 g calibrated Von-Frey monofilaments to determine sensitivity to light touch and pain stimulation over a 4 to 8 h period. Pain-related behaviour was documented by trained, blinded observers using a numerical rating scale. Wound healing rates were determined using scaled digital photography and image analysis software to calculate contraction in wound surface area 2 and 4 weeks after mulesing.
Results     There was rapid (3 min) and prolonged (up to 8 h) wound analgesia as shown by pain response scores (P ≤ 0.01), with absent or significantly diminished primary and secondary hyperalgesia (P ≤ 0.01) and significant reduction in pain-related behaviour (P < 0.001) in treated versus untreated lambs. In addition there was improved wound healing in the treated lambs (P ≤ 0.05).
Conclusion     Tri-Solfen® effects rapid and prolonged wound analgesia, reduction in pain-related behaviour and improved wound healing in lambs undergoing routine mulesing, providing effective alleviation of pain associated with routine mulesing in sheep.     

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.     

A simple device for respiratory resuscitation of newborn calves and lambs

The neonatal death of calves and lambs is responsible for a heavy financial loss to the farming industry; respiratory failure accounts for 6 per cent of the post parturient deaths in lambs. A simple method of pulmonary resuscitation with expired air is described employing a device portable and simple enough for emergency use by herdsmen and shepherds. The rationale of the use of the equipment is explained.     

Acute cortisol responses of lambs castrated and docked using rubber rings with or without a castration clamp

Objective To measure the plasma cortisol response in lambs castrated and docked by three different methods (ring castration and tail docking, ring and clamp castration and tail docking; ring and clamp castration and ring tail docking) for 4 h after treatment.
Design A physiological study with controls.
Procedure A rubber ring was applied to the scrotum. Then the castration clamp was placed, distal to the ring, on each spermatic cord such that there was no overlap of the crush lines.
Results There were no differences in the cortisol secretion of the lambs castrated and tail docked by the ring only and by the ring plus castration clamp methods. Using the castration clamp in addition to the ring on the tail had no effect on cortisol secretion.
Conclusions Using the castration clamp did not appear to reduce the cortisol response to ring castration and docking, as demonstrated elsewhere, because the areas of uncrushed tissue between the two castration clamp crush lines allowed nociception from ischemic scrotal tissue to be transmitted cranially via undamaged nerve fibers.     

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.     

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.     

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.     

The effect of tilmicosin administered to ewes prior to lambing on incidence of clinical mastitis and subsequent lamb performance

The effect of tilmicosin on the incidence of clinical mastitis and subsequent lamb performance was studied in 9 sheep flocks in Ontario. Ewes were treated randomly with either tilmicosin or placebo approximately one month prior to lambing. Outcome was assessed by comparing rates of clinical mastitis, palpable udder abnormalities, and preweaning (50-day) lamb weights between the 2 treatment groups, while controlling for other important variables. Lambs raised by multiparous ewes treated with tilmicosin were significantly heavier than lambs from placebo-treated multiparous ewes at 50 days. Lambs from tilmicosin-treated ewes were on average 0.52 kg heavier than lambs in the placebo group. There was no difference between treatment groups in the weight of lambs from first parity ewes. Tilmicosin treatment resulted in a 43% decrease in palpable udder abnormalities. Incidence of clinical mastitis did not differ between experimental groups. The administration of tilmicosin prelambing, at the time of routine clostridial disease vaccination, may be a beneficial and convenient way to reduce mastitis infection and improve the preweaning gain of lambs.     

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.     

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.     

Analgesia of newborn lambs before castration and tail docking with rubber rings

This study assessed the effects of suckled sucrose and parenteral carprofen treatment on behavioural measurements of discomfort and serum haptoglobin concentration in lambs following rubber ring castration and/or tail docking. Twenty-eight male and 20 ewe lambs were allocated to either a male or ewe lamb control group (n=4) or to one of three male and two ewe lamb treatment groups (n=8). Male lambs in one treatment group received carprofen subcutaneously (0.5 mg/kg) 30 minutes before castration and docking. Lambs in all other treatment groups suckled sucrose or colostrum immediately before castration and/or tail docking. Behavioural measurements of discomfort were made following castration or tail docking in treatment groups and also in control animals which were not castrated or tail docked. Blood sampling of animals in treatment groups for analysis of serum haptoglobin, an acute phase protein used as an indicator of an acute inflammatory response, was performed before castration or docking and at 24 and 48 hours after castration or docking. Control lambs were blood sampled at 0, 24 and 48 hours following behavioural assessment Neither suckled sucrose nor carprofen treatment altered discomfort behaviour associated with castration or tail docking. Haptoglobin levels following castration or tail docking remained close to the detection limits of the assay and were similar to those recorded in control animals.     

Effects of tail docking and castration on behaviour and plasma cortisol concentrations in young lambs

Behavioural and cortisol responses of lambs to the usual husbandry practices of castration and, or, tail docking using tight rubber rings were investigated between birth and seven days old. There were four treatments: control handling and blood sampling (n = 52), tail-docking (T) (n = 57), castration plus tail-docking (CT) (n = 54) and intravenous adrenocorticotrophin injection (ACTH) (n = 52). After treatment there was a transient rise in plasma cortisol concentration, the magnitude and duration of which increased in the following order; control, T, CT and ACTH. Behavioural characteristics indicative of distress included restlessness (standing up and lying down frequently, rolling, kicking, stamping), lateral recumbency, immobility with neck extension and hyperventilation. Using changes in cortisol concentrations and behaviour the lamb responses were characterised as reflecting 'mild disturbance without distress' (control, ACTH), 'mild distress' (T) and 'marked distress' (CT). The mild distress lasted for about 30 minutes in T lambs and marked distress for about 60 minutes in CT lambs.