Do psychological and physiological stressors alter the acute pain response to castration and tail docking in lambs?

Sex impacts pain behaviour but not emotional reactivity of lambs following ring tail docking

Studies in humans have shown sex differences in response to painful events, however, little is known in relation to sex differences in sheep. Understanding sex differences would enable improved experimental design and interpretation of studies of painful procedures in sheep. To examine sex differences in response to pain, 80 lambs were tested across five cohorts of 16. The lambs were penned in groups containing two male and two female lambs with their respective mothers. Lambs were randomly allocated from within each block to one of four treatment groups; FRing–Female lamb, ring tail docked without analgesia, MRing–Male lamb, ring tail docked without analgesia, FSham–Female lamb, tail manipulated and MSham–Male lamb, tail manipulated. Following treatment, lambs were returned to their pen and were video recorded for 45 mins for behavioural observations of acute pain and posture. An hour after treatment, lambs then underwent an emotional reactivity test that consisted of three phases: Isolation, Novelty and Startle. Following treatment, Ring lambs displayed more abnormal postures (mean = 2.5 ± 0.5) compared to Sham lambs (mean = 0.05 ± 0.4, P = 0.0001). There was an effect of sex on the display of acute pain-related behaviours in lambs that were tail docked (P < 0.001), with female lambs displaying more acute behaviours (mean count = +2.2). This difference in behaviour between sexes was not observed in Sham lambs. There was no effect of sex on display of postures related to pain (P = 0.99). During the Novelty and Startle phase of the emotional reactivity test, Ring lambs tended to (P = 0.084) or did (P = 0.018) show more fear related behaviours, respectively. However, no effect of sex was observed. The results of this study indicate that a pain state may alter the emotional response of lambs to novel objects and potential fearful situations. It was also demonstrated that female lambs display increased sensitivity to the acute pain caused by tail docking compared to males.

Role of Topical Anaesthesia in Pain Management of Farm Animals, a Changing Paradigm

Field evidence indicates that livestock producers are motivated by access to products that readily deliver pain management during husbandry interventions and, more recently, viral epidermal infectious diseases, including FMD. There has been impressive adoption in Australia of a farmer-applied spray-on topical anaesthetic wound formulation (TAF; Tri-Solfen®, Medical Ethics, Australia), initially for managing pain of the breech modification ‘mulesing’ procedure that reduces susceptibility of sheep to flystrike. Over 120 million lambs have now received pain relief and cattle producers have commenced using the TAF for a range of husbandry procedures. This product has demonstrated efficacy for surgical castration and tail docking of lambs, surgical castration and dehorning of calves, surgical castration of piglets, debridement of lesions of the hoof for lame cattle and, importantly, treatment of clinical FMD lesions, including decubitus ulcerations occurring from prolonged recumbency. Multimodal use of an NSAID for improved pain management is advocated, particularly meloxicam, available by prescription from veterinarians for injection and as an oral formulation (Ilium Buccalgesic®, Troy Laboratories, Australia), with current work assessing the potential for prolonged delivery in molasses blocks. Increased use of TAF with NSAIDs significantly reduces pain and suffering in livestock, with enhanced healing of FMD lesions, reduced viral loads from Orf infections in lambs and diminished necessity of ‘antibiotic cover’, assisting antimicrobial-resistance (AMR) stewardship.

Impact of a Topical Anaesthesia Wound Management Formulation on Pain, Inflammation and Reduction of Secondary Infections after Tail Docking in Lambs

Simple Summary

Tail docking is routinely conducted in sheep husbandry around the world, often without anaesthesia or analgesia despite recognition that it is a painful process. Several methods are used, although the Council of Europe states that surgical methods with anaesthesia should be used to dock the tail, with these recommendations copied into national legislation by most European countries. However, no studies have been documented comparing the use of general anaesthesia and stitching. This study compared different surgical approaches with and without general anaesthesia, and with and without surgical stitching, plus examined the efficacy of applying a commercially available wound gel spray containing topical anaesthetics and an antiseptic, immediately on tail amputation. Results demonstrated that lambs display more pain when the surgery included stitching and these wounds became more readily infected, potentially requiring antibiotic therapy. As the generation of potential antimicrobial resistance and drug residues issues in food-producing animals from over-use of antibiotics is an emerging one health consideration, the availability of a topical anaesthetic formulation that provides pain relief and contains an antiseptic that reduces secondary infections and hasten wound healing, is of potential importance for improving husbandry procedures such as tail docking.

Abstract

We examined several procedures for surgical tail docking; with and without general anaesthesia (GA), including the use of a topical wound gel formulation to provide pain relief (PR) and improve healing after surgery, containing local anaesthetics lignocaine and bupivacaine, with cetrimide and adrenalin. Forty-four lambs were recruited into four equal cohorts: Groups A and C, the tail was excised with a scalpel without anaesthesia or stitches; Groups B and D, the tail was surgically excised and stitched under GA; Groups C and D wounds were immediately sprayed with PR. Behavioural observations identified that Groups A and C displayed significantly less pain-related behaviours than Groups B and D shortly after the procedure, especially if treated with PR. Similarly, the mean of days when animals showed no signs of wound infection was longer in the groups not undergoing stitching. Finally, treatment with PR appeared to reduce the cortisol response and avoided the elevation of serum amyloid A in lambs where the tail was excised without general anaesthesia. In conclusion, surgical tail-docking without GA but where wounds are immediately sprayed with PR, appears as an affordable and more welfare-appropriate method for conducting tail docking in lambs.

Evaluating the efficacy of a topical anaesthetic formulation and ketoprofen, alone and in combination, on the pain sensitivity of dehorning wounds in Holstein-Friesian calves

The aim of this study was to investigate the effect of a topically applied local anaesthetic and the non-steroidal anti-inflammatory drug ketoprofen, alone and in combination, on the pain sensitivity response of calves to dehorning (mean age 2.2 months). Calves were randomly allocated and blocked by age to one of four groups. Groups were: scoop dehorning (D, n = 8), scoop dehorning + i.m. administration of 3 mg/kg ketoprofen (DK, n = 8), scoop dehorning + application of topical anaesthetic (DTA, n = 7) and scoop dehorning + application of topical anaesthetic and i.m. administration of ketoprofen (DKTA, n = 7). A pressure algometer was used to determine the mechanical nociceptive threshold (MNT), being the pressure (kg/f) at which calves withdrew from the stimulus. Measurements were taken before dehorning and at 1 min, 1, 2, 5 and 24 h post-dehorning at both the cut skin edge of the wound and the peri-wound area. The effect of treatment changed over time (P < 0.001). MNT was highest before treatment (MNT = 5.03 kg/f) and tended to decrease over time (MNT = 1.16 kg/f 24 h post-treatment). Overall, D calves exhibited the lowest MNT with an average of 1.77 kg/f. DTA calves had the highest MNT (3.89 kg/f), followed closely by DKTA calves (3.24 kg/f). DK calves exhibited an intermediate MNT of 2.61 kg/f. MNT of the cut skin edge was generally lower than that of the peri-wound area (2.01 vs 3.81 kg/f, respectively, P = 0.02).The topical anaesthetic formulation significantly reduced the pain sensitivity of dehorning wounds. There was no observed enhanced analgesic effect with addition of ketoprofen. The cut skin edge was more sensitive to pressure than the peri-wound area.

Long-term and trans-generational effects of neonatal experience on sheep behaviour

Early life experiences can have profound long-term, and sometimes trans-generational, effects on individual phenotypes. However, there is a relative paucity of knowledge about effects on pain sensitivity, even though these may impact on an individual's health and welfare, particularly in farm animals exposed to painful husbandry procedures. Here, we tested in sheep whether neonatal painful and non-painful challenges can alter pain sensitivity in adult life, and also in the next generation. Ewes exposed to tail-docking or a simulated mild infection (lipopolysaccharide (LPS)) on days 3–4 of life showed higher levels of pain-related behaviour when giving birth as adults compared with control animals. LPS-treated ewes also gave birth to lambs who showed decreased pain sensitivity in standardized tests during days 2–3 of life. Our results demonstrate long-term and trans-generational effects of neonatal experience on pain responses in a commercially important species and suggest that variations in early life management can have important implications for animal health and welfare.

Pain-Suppressed Behaviors in the Red-tailed Hawk (Buteo jamaicensis)

Our ability to provide analgesia in wild and exotic patients is hampered by a lack of species-specific information on effective drugs and protocols. One contributing factor is the difficulty of applying data from traditional laboratory tests of nociception to clinical conditions frequently involving combinations of inflammatory, mechanical, and neuropathic pain. Pain-suppressed behaviors have become a valuable predictor of clinical utility in other species; in this study we extend this framework to red -tailed hawks in a wildlife hospital, in an attempt to develop a new, humane testing method for birds of prey. We scored six behaviors in hawks hospitalized either for orthopedic trauma or for non-painful conditions. These behaviors included: movement about the cage, grooming, head motions, foot shifts, beak clacks, and rouse. Movement, head motions, and beak clacks were all significantly reduced in hawks with recent orthopedic injury, but not in hawks with healed or minor injuries (P<0.05 for all behaviors). However, it should be noted that due to stringent admission criteria, and the difficulties inherent in studying naturally-occuring injury in wild patients, this study only included -subjects in four experimental groups, and this limited our ability to fully investigate confounds within our data. A follow-up experiment was conducted to determine potential effects of buprenorphine, a mu opioid agonist, on the behaviors listed above. Buprenorphine in the absence of pain caused minor, non-significant decreases in most behaviors, and had no effect on head movement frequency. This suggests that head movements in particular may be sensitive to pain but not to sedative side-effects of buprenorphine. Overall, red -tailed hawks with recent orthopedic trauma show consistent and marked red uctions in several normal maintenance behaviors. Head movements, reported for the first time in this study as a potential marker of pain in birds, in particular seem to be insensitive to sedative side effects of buprenorphine, while being a sensitive measu re of affective state in hawks with painful injuries. These behaviors can be scored humanely and with minimal expense, and should be considered for further research on pain and analgesia in avian species.

Experience with the delegation of anaesthesia for disbudding and castration to trained and certified livestock owners

Background

Anaesthesia is mandatory for disbudding and castrating calves and lambs of any age, in Switzerland. According to the “anaesthesia delegation model” (ADM), anaesthesia for disbudding calves <3 weeks of age and castrating calves and lambs <2 weeks of age may be administered by certified farmers. Experience with this unique model is not available. The aim was to evaluate the experience of the veterinary practitioners with the ADM. The response rate was 42%. The survey consisted of one questionnaire for each procedure. Procedure I was the delegation of anaesthesia for disbudding calves and procedures II and III were anaesthesia for castrating calves and lambs.

Results

Procedure I was performed with local anaesthesia in all farms of 51.8% of the veterinary practices, while this was only 39.3% and 7.6% for procedures II and III (p < 0.001). Anaesthesia for procedure I was administered technically correctly by farmers in at least 66% of the farms of 58.3% of the practitioners, while this was 45.4% and only 23.6% for procedures II and III (p < 0.001). The ADM was assessed as a moderate to very good model to reinforce the legal obligations for procedures I, II, or III by 74.8%, 76.5% and 62.0% of the veterinary practitioners (p < 0.005).

Conclusions

The delegation of anaesthesia to certified farmers may be a promising model to reinforce the obligation to provide local anaesthesia for disbudding and castrating calves, but to a lesser extent for castrating lambs.

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.