Our ability to assess pain in animals in clinical situations is slowly developing, but remains very limited. In order to develop appropriate pain scoring schemes, numerous practical problems need to be overcome. In addition, we need to appraise realistically our current poor state of knowledge. Development of new scoring systems must be coupled with the increased education and training of those responsible for pain management, so that both the assessment and the alleviation of pain are steadily improved.

In humans, psychological manipulations such as hypnosis, behavioural modifications, relaxation training and cognitive behaviour therapy have all been used to reduce pain intensity. One thing these treatments have in common is selective attention. Work on attention-based cognitive coping strategies has shown that they have potentially useful analgesic qualities in pain therapy. In animals, there have been few studies on the effects of attentional shifts on pain perception. There is extensive literature on stress-induced analgesia and it is likely that, in some of the experiments, attention could be an important variable. This paper will present some of our recent work on selective attention and pain perception using the sodium urate model of gouty arthritis. Birds are naturally prone to articular gout and the model we have developed mimics acute gouty attacks in a single joint. Experimental sodium urate arthritis produces a tonically painful inflammation lasting for at least 3h during which time the animals show pain-related behaviours. Changes in motivation can reduce these pain-related behaviours and it has been hypothesized that these motivational changes act by way of altering the attention of the animal away from pain. The motivational changes investigated included nesting, feeding, exploration and social interactions. The degree of pain suppression ranged from marked hypoalgesia to complete analgesia and as such demonstrates a remarkable ability to suppress tonic pain. These shifts in attention not only reduced pain but also significantly reduced peripheral inflammation. These results are discussed in terms of the limited capacity models of attention.

The aim of this preliminary study was to identify key behavioural indicators of pain in cats. The behaviour of cats before and after ovariohysterectomy was analysed using a detailed behavioural ethogram. A comparison of behaviours between cats given pre-operative analgesia only and cats given both pre- and post-operative analgesia indicated that both groups demonstrated changed behaviour following surgery, compared to a control group of cats which underwent anaesthesia but not surgery. However, some specific postures, such as ‘half-tucked-up’ and ‘crouching’, were identified that occurred with greater frequency in the cats receiving pre-operative analgesia only, as compared to those receiving additional post-operative analgesia. This indicates that there are some key behaviours that may be useful in determining pain in cats. Routine administration of pre- but not post-operative analgesia may be ineffective for adequately alleviating pain in cats.

Sucrose has been shown to attenuate the behavioural response to painful procedures in human infants undergoing circumcision or blood collection via heelstick. Sucrose has also been found to have a behaviour-modifying effect in neonatal rats exposed to a hot plate. The effect was abolished in neonatal rats by injection of the opioid antagonist naltrexone, suggesting that it was mediated by endogenous opioids. In this experiment, the behaviour of 571 newborn Large White x Landrace hybrid piglets in a specific-pathogen-free piggery of the University of Queensland was recorded during and after the routine management practices of tail docking, ear notching and teeth clipping. Piglets were randomly assigned to receive 1.0 ml of a 12% sucrose solution (treatment group) or a placebo (1.0 ml of air) administered via syringe in the mouth, 60 s before commencement of one of the management procedures. Behaviours were recorded at the time of the procedure, and then 2 min after completion of the procedure. Piglets that received the sucrose solution did not behave significantly differently from piglets receiving the placebo. Regardless of whether sucrose or placebo was administered, piglets undergoing the routine management procedures showed significantly greater behavioural responses than piglets undergoing no procedure. It was concluded that under commercial conditions, a 12% sucrose solution administered 1 min prior to surgery was not effective in decreasing the behavioural indicators of distress in piglets undergoing routine management procedures. Further research into methods of minimising distress caused to piglets by these procedures is recommended.

Piglets on commercial pig farms are often tail-docked to reduce the incidence of tail-biting. While this is a painful procedure, piglets are often not provided analgesia or anaesthesia for pain relief. The objectives of this study were to assess a multimodal approach to managing tail-docking pain in piglets, using 0.4 mg kg-1 meloxicam (MEL), 0.04 mg kg-1 buprenorphine (BUP), and Maxilene® (MAX), a topical anaesthetic. The effectiveness of each drug and drug combination was evaluated using behavioural indicators, vocalisation, and facial grimace analysis. This study also assessed whether male and female piglets responded differently to pain or pain treatments. Piglets were randomly assigned to one of six possible treatments: MEL, BUP, MEL + BUP, MEL + BUP + MAX, no treatment (tail-docked control), or sham (non-tail-docked control). Vocalisations were recorded at initial handling, injection, and tail-docking. Piglets administered MEL + BUP and BUP demonstrated significantly fewer pain behaviours than piglets in the MEL and no treatment group. MEL + BUP + MAX and BUP piglets displayed significantly lower facial grimace scores than piglets in the no treatment group. There were no significant differences in emitted vocalisations between the analgesia-treated piglets and the no treatment group and both injection and tail-docking elicited piglet vocalisations of similar frequency, power, and energy. There were no significant differences in behaviour, facial grimacing or emitted vocalisations between male and female piglets. All treatment groups with buprenorphine were able to alleviate tail-docking-associated pain, suggesting that opioid administration is highly effective for managing piglet pain.

Buprenorphine is a widely used analgesic for laboratory rodents. Administration of the drug in a desirable food item for voluntary ingestion is an attractive way to administer the drug non-invasively. However, it is vital that the animals ingest the buprenorphine-food-item mix as desired. The present study investigated how readily female and male mice (Mus musculus) of two different strains consumed buprenorphine mixed in a commercially available nut paste (Nutella®), and whether variation between genders and strains would affect the subsequent serum concentrations of buprenorphine. Buprenorphine at different concentrations mixed in Nutella® was given to male and female C57BL/6 and BALB/c mice in a complete cross-over study. Pure Nutella® or buprenorphine (1.0-3.0 mg kg−1 bodyweight [bw]) mixed in 10 g kg−1 bw Nutella® were given to the mice at 1500h. The mice were video recorded until the next morning, when blood was collected by submandibular venipuncture. The concentration of buprenorphine in the Nutella® mix did not affect the duration of ingestion in any of the groups. However, female mice consumed the Nutella® significantly faster than males. Repeated exposure significantly reduced the start time of voluntary ingestion, but not the duration of eating the mixture. These differences did not however affect the serum concentration of buprenorphine measured 17 h post administration.

Surgical castration of piglets is a routine procedure on commercial pig farms, to prevent boar taint and reduce aggression. This procedure is known to cause pain, yet piglets are often not provided appropriate analgesia for relief. The objective of this study was to assess a multimodal approach to managing post-castration pain in piglets, using 0.4 mg kg-1 meloxicam (MEL), 0.04 mg kg-1 buprenorphine (BUP), and Maxilene® (MAX). Efficacy was evaluated using behavioural indicators, vocalisation, and facial grimace analysis. Male piglets were randomly assigned to one of ten possible treatments (n = 15 piglets per treatment group): MEL + BUP + MAX (castrated or uncastrated); MEL + BUP (castrated or uncastrated); BUP + MAX (castrated or uncastrated); MEL + MAX (castrated or uncastrated); saline (castrated control); or sham (uncastrated control). Castrated piglets in the MEL + BUP + MAX, MEL + BUP, and BUP + MAX treatment groups displayed significantly fewer pain behaviours than piglets administered saline. MEL + MAX was insufficient in reducing surgical castration pain behaviours. At 24 h post-procedure, saline and MEL + MAX-castrated piglets displayed significantly more pain behaviours than all other treatment groups and time-points. Facial grimace analysis indicated that MEL + MAX-castrated piglets had significantly higher grimace scores than MEL + BUP (castrated and uncastrated) and BUP + MAX-uncastrated. There were no significant differences in emitted vocalisations between the analgesia-treated and saline-castrated piglets. All treatment groups with buprenorphine were effective in alleviating castration-associated pain behaviours, suggesting that opioid administration is beneficial for managing piglet castration pain.

This study aimed to identify behaviours that could be used to assess post-operative pain and analgesic efficacy in male rabbits. In consideration of the ‘Three Rs’, behavioural data were collected on seven male New Zealand White rabbits in an ethically approved experiment requiring abdominal implantation of a telemetric device for purposes other than behavioural assessment. Prior to surgery, rabbits were anaesthetised using an isoflurane/oxygen mix and given Carprofen (2 mg kg−1) as a peri-operative analgesic. Rabbits were housed individually in standard laboratory cages throughout. Data were collected at three time periods: 24-21 h prior to surgery (T1) and, post-surgery, 0-3 h (T2) and 3-6 h (T3). Behavioural changes were identified using Observer XT, significance of which was assessed using a Friedman's test for several related samples. The frequency or duration of numerous pre-operative behaviours was significantly reduced in T2 and T3, as compared to T1. Conversely, novel or rare behaviours had either first occurrence or significant increase in T2 into T3 as compared to T1, these include ‘full-body-flexing’, ‘tight-huddling’, ‘hind-leg-shuffling’. We conclude that reduced expression of common pre-operative behaviours and the appearance of certain novel post-operative behaviours may be indicative of pain in rabbits. Behaviours identified as increased in T2 as compared to T1 but not consistently elevated into T3 were considered separately due to the potentially confounding effect of anaesthesia recovery. These included lateral lying, ‘drawing-back’, ‘staggering’ and ‘closed eyes’. We postulate that for effective application of best-practice post-operative care, informed behavioural observation can provide routes by which carers may identify requirements for additional post-operative analgesia. Additionally, improvement of the peri-operative pain management regimen may be required to ameliorate the immediate effects of abdominal surgery. Comparisons with other studies into post-operative pain expression in rabbits suggest behavioural indicators of pain may differ, depending on housing and surgical procedure.

Lame broiler chickens perform poorly in standardised mobility tests and have nociceptive thresholds that differ from those of nonlame birds, even when confounding factors such as differences in bodyweight are accounted for. This study investigated whether these altered responses could be due to pain, by comparing performance in a Group Obstacle test and a Latency to Lie (LTL) test of lame (Gait Score [GS] 2.5-4) and non-lame (GS 0-1) broilers administered analgesia or a saline control. We used exploratory subcutaneous doses of the non-steroidal anti-inflammatory drugs (NSAIDs), meloxicam (5 mg kg−1) or carprofen (35 mg kg−1) or the opioid butorphanol tartrate (4 mg kg−1). We included butorphanol to explore the possibility that NSAIDs could improve mobility by reducing inflammation without necessarily invoking an analgesic effect. Lameness was a significant predictor in all analyses. Neither the number of obstacle crossings nor latency to cross an obstacle was significantly changed by either NSAID, but LTL was longer in lame birds given carprofen and meloxicam than in lame birds given saline. LTL was associated with foot-pad dermatitis and ameliorated by both NSAIDs. Butorphanol did not affect LTL but appeared soporific in the obstacle test, increasing latency to cross and, in non-lame birds, reducing the number of crossings. Combined with data from other studies, the results suggest carprofen and meloxicam had some analgesic effect on lame birds, lending further support to concerns that lameness compromises broiler welfare. Further investigation of opioid treatments and lameness types is needed to disentangle effects on mobility and on pain.

The study examined cattle farmers' and veterinarians' opinions of pain-induced distress associated with disbudding and attitudes towards non-steroidal anti-inflammatory drugs (NSAIDs). An emphasis was placed on investigating pain perception, veterinary-client communication and factors influencing analgesic use. Data were collected from an online questionnaire, links to which were published in professional periodicals, promoted by industry organisations and distributed on private practice mailing lists. A total of 110 veterinarians and 116 farmers who regularly disbud calves completed the questionnaires. Of the respondents, 56% of veterinarians and 14% of farmers routinely use NSAIDs for disbudding. Respondents perceived disbudding to be severely painful without medication and 82% of veterinarians and 43% of farmers perceived post-procedural pain to persist beyond 24 h. There was a significant difference between female and male veterinarians' pain scores for disbudding without medication. Veterinarians underestimate the influences of welfare and analgesic duration and effectiveness on farmers' decisions and overrated cost impact. The study highlights that improvements in veterinarian-farmer communication regarding calf disbudding analgesia are required; both in terms of refining veterinarians' understanding of farmers' priorities and guiding clients on methods to improve calf welfare.