The effect of chronic clinical pain on thermal and mechanical thresholds in sheep

Measurement properties of pain scoring instruments in farm animals: A systematic review using the COSMIN checklist

This systematic review aimed to investigate the measurement properties of pain scoring instruments in farm animals. According to the PRISMA guidelines, a registered report protocol was previously published in this journal. Studies reporting the development and validation of acute and chronic pain scoring instruments based on behavioral and/or facial expressions of farm animals were searched. Data extraction and assessment were performed individually by two investigators using the Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN) guidelines. Nine categories were assessed: two for scale development (general design requirements and development, and content validity and comprehensibility) and seven for measurement properties (internal consistency, reliability, measurement error, criterion and construct validity, responsiveness and cross-cultural validity). The overall strength of evidence (high, moderate, low, or very low) of each instrument was scored based on methodological quality, number of studies and studies' findings. Twenty instruments for three species (bovine, ovine and swine) were included. There was considerable variability concerning their development and measurement properties. Three behavior-based instruments scored high for strength of evidence: UCAPS (Unesp-Botucatu Unidimensional Composite Pain Scale for assessing postoperative pain in cattle), USAPS (Unesp-Botucatu Sheep Acute Composite Pain Scale) and UPAPS (Unesp-Botucatu Pig Composite Acute Pain Scale). Four instruments scored moderate for strength of evidence: MPSS (Multidimensional Pain Scoring System for bovine), SPFES (Sheep Pain Facial Expression Scale), LGS (Lamb Grimace Scale) and PGS-B (Piglet Grimace Scale-B). Most instruments (n = 13) scored low or very low for final overall evidence. Construct validity was the most reported measurement property followed by criterion validity and reliability. Instruments with reported validation are urgently required for pain assessment of buffalos, goats, camelids and avian species.

Effect of a targeted pain management protocol for the treatment of dermatitis interdigitalis contagiosa in Merino meat sheep in a tilt squeeze chute

Introduction

The effect of a targeted pain management protocol consisting of sedation and local anesthesia on the stress response to treatment of dermatitis interdigitalis contagiosa (DINCO) was assessed in sheep placed in dorsal recumbency.

Methods

Blood cortisol concentrations were measured once a day (Day -3 to 2) and additionally on day 0, six times during the claw treatment (stress model). Twelve healthy sheep (control group; HEALTHY) and 36 sheep with DINCO, randomly allocated to one of three treatment groups, underwent the stress model with or without pain control: the XYLA-IVRA sheep were sedated with 2% xylazine hydrochloride (XYLA) and received retrograde intravenous regional anesthesia (IVRA); the IVRA sheep underwent IVRA and received a placebo instead of sedation; the PLACEBO sheep received placebos for sedation and IVRA. The HEALTHY sheep underwent sham claw treatment and received placebos.

Results and discussion

The cortisol concentrations were higher in sheep restrained in dorsal recumbency compared with the cortisol concentrations measured four hours later in standing sheep (HEALTHY 37.2 ± 3.3 ng/ml vs. 18.5 ± 3.3 ng/ml; DISEASED 34.0 ± 1.9 ng/ml vs. 17.6 ± 1.9 ng/ml; p < 0.001). The stress response of XYLA-IVRA (area under the curve; AUC = 34.9 ± 2.6 ng/ml) was reduced compared with the stress response of PLACEBO (AUC = 48.0 ± 2.6 ng/ml, p < 0.01) and HEALTHY sheep (AUC = 46.6 ± 2.5 ng/ml; p = 0.01). While cortisol concentration of XYLA-IVRA and HEALTHY sheep did not increase one day after the stress model (Day 1) compared with the day of the stress model (Day 0), both PLACEBO (47.4 ± 3.3 vs. 35.6 ± 3.1 ng/ml, p = 0.02) and IVRA sheep (39.1 ± 2.8 vs. 28.6 ± 3.1 ng/ml, p = 0.01) had higher cortisol concentrations. The results confirm that fixation in dorsal recumbency in a tilt squeeze chute was a major stressor in sheep. The differences in the cortisol concentration of the PLACEBO sheep versus the XYLA-IVRA sheep during and after the stress model illustrate the effect and necessity of pain management protocols in practice.

Welfare of small ruminants during transport

In the framework of its Farm to Fork Strategy, the Commission is undertaking a comprehensive evaluation of animal welfare legislation. The present Opinion deals with the protection of small ruminants (sheep and goats) during transport. The main focus is on welfare of sheep during transport by road but other means of transport and concerns for welfare of goats during transport are also covered. Current practices related to transport of sheep during the different stages (preparation, loading and unloading, transit and journey breaks) are described. Overall, 11 welfare consequences were identified as being highly relevant for the welfare of sheep during transport based on severity, duration and frequency of occurrence: group stress, handling stress, heat stress, injuries, motion stress, predation stress, prolonged hunger, prolonged thirst, restriction of movement, resting problems and sensory overstimulation. These welfare consequences and their animal-based measures are described. A wide variety of hazards, mainly relating to inappropriate or aggressive handling of animals, structural deficiencies of vehicles and facilities, unfavourable microclimatic and environmental conditions and poor husbandry practices, leading to these welfare consequences were identified. The Opinion contains general and specific conclusions in relation to the different stages of transport. Recommendations to prevent hazards and to correct or mitigate welfare consequences have been developed. Recommendations were also developed to define quantitative thresholds for microclimatic conditions within the means of transport and spatial thresholds (minimum space allowance). The development of welfare consequences over time were assessed in relation to maximum journey time. The Opinion covers specific animal transport scenarios identified by the European Commission relating to the export of sheep by livestock vessels, export of sheep by road, roll-on-roll-off vessels and 'special health status animals', and lists welfare concerns associated with these.

Measurement properties of pain scoring instruments in farm animals: A systematic review protocol using the COSMIN checklist

Society has been increasingly concerned about the impact of pain on farm animal welfare. This systematic review aims to provide evidence relating to the measurement properties (i.e. reliability, validity, and sensitivity) of pain scoring instruments used for pain assessment in farm animals. A literature search will be performed using five databases (MEDLINE, EMBASE, Web of Science, CAB abstracts and Biological Abstracts) and search terms related to pain, pain scales and different species of farm animals. Eligibility criteria will include full-text studies on the development and/or validation of acute and chronic pain scoring instruments for farm animals including bovine (beef and dairy), ovine, caprine, camel, swine and poultry. Exclusion criteria will include studies that report the use of pain scales for the validation of another instrument, or those reporting ethograms/list of behaviors potentially indicating pain without a scoring system. Study titles and their abstracts will be screened for eligibility by one investigator. Full-text articles will be independently reviewed for eligibility and evaluated by two investigators. Relevant information will be recorded and evaluated systematically according to the Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN) checklist using an adapted data collection sheet. The following measurement properties and characteristics of the instruments will be assessed: content validity (internal consistency, structural and cross-cultural validity), reliability, measurement error, criterion and construct validity, responsiveness, interpretability and feasibility. Following the assessment of methodological quality and quality of the findings, evidence for each measurement property will be summarized into high, moderate, low or very low. This systematic review will provide further insights into the evidence-based measurement properties of pain scoring instruments in farm animals. It may identify possible gaps of knowledge with these tools as a potential target for future studies in farm animals with a positive impact on animal welfare.

Heat hypersensitivity at a site proximal to a surgically induced osteochondral fracture in horses

OBJECTIVE

To evaluate thermal nociceptive thresholds (TNTs) before and after inducing a standardized radiocarpal bone osteochondral fracture (OCF) in horses.

STUDY DESIGN

Prospective, controlled, randomized, masked study.

ANIMALS

A group of 10 Thoroughbred fillies aged 2 years.

METHODS

Skin temperature and TNTs were measured on the skin over the triceps brachii muscle in both the thoracic limbs before (week 0) and weekly (weeks 1-8) after unilateral arthroscopic induction of a radiocarpal OCF (n = 4) or sham surgery (n = 6) followed by a standardized exercise programme. The contralateral, non-operated thoracic limb was used as a control within each horse. Percentage thermal excursion (%TE) defined as %TE = 100 ∗ (TNT - skin temperature)/(cut-off temperature - skin temperature) was calculated. Data were analysed with a mixed-effects model followed by Dunnett's and Tukey's tests for within and between-limbs comparisons, respectively; p < 0.05 was considered significant.

RESULTS

Skin temperature in the control limb of OCF horses was significantly higher at week 7 than at week 0 (p = 0.0125). At week 1, TNTs and %TE values in operated limbs of OCF horses were significantly reduced compared with their baseline values at week 0 (p ≤ 0.0153) and their values in contralateral control limbs (p ≤ 0.0024) and operated limbs of sham-operated horses (p ≤ 0.0162). At week 2, TNTs and %TE values in operated limbs of OCF horses remained significantly reduced compared with values in operated limbs of sham-operated horses (p ≤ 0.0248).

CONCLUSIONS AND CLINICAL RELEVANCE

Creation of an OCF in a radiocarpal bone induced transitory (<2 weeks) ipsilateral heat hypersensitivity proximal to the surgery site (skin over the triceps brachii muscle) in horses. Surgically induced OCF may cause somatosensory abnormalities consistent with secondary thermal hyperalgesia.

Glaucoma-associated pain results in mechanical sensitivity changes in dogs: A pilot study

PURPOSE

To explore the effects of chronic, uncontrolled glaucoma on pressure sensitivity in dogs before and after enucleation of the painful globe.

METHODS

Client-owned dogs undergoing enucleation for chronic glaucoma with no other sources of pain were enrolled. Normal dogs of similar breeds and skull morphology were enrolled as controls. Craniofacial ratio (CFR) and relative palpebral fissure width (RPFW) were assessed in all patients. Serial mechanical quantitative sensory testing (QST) was performed the day before surgery, and 14, 30, 60, and 120 days after surgery. QST consisted of electronic Von Frey (eVF), and blunt algometry (BA) performed above and below the nonglaucomatous eye, the metacarpus, and metatarsus. Cochet-Bonnet esthesiometry (CB) was also performed on the remaining eye.

RESULTS

Twelve dogs (6 per group) were included. Compared to baseline values, sensitivity tended to decrease over time (increased thresholds) in treatment dogs while it stayed constant or increased slightly in control dogs. The difference in change from baseline sensitivity between control and treatment groups was significant at day 120 using BA at supraorbital (P = .0153), infraorbital (P = .0209), and metacarpal sites (P = .007) and overall (P = .0470). This divergence was also significant using CB (P = .0470) on the opposite cornea. As patient CFR and RPFWV increased, both eVF (P = .005-.023) and BA (P = .004-.041) increased.

CONCLUSIONS

Sensitivity to mechanical stimuli decreased both locally and at remote sites in dogs following enucleation for painful chronic glaucoma. Cranial conformation is associated with differences in sensitivity.

Increase in the flock prevalence of lameness in ewes is associated with a reduction in farmers using evidence-based management of prompt treatment: A longitudinal observational study of 154 English sheep flocks 2013-2015

Since 2006, farmers in England have received new recommendations on best practice to manage lameness in sheep through a range of knowledge exchange activities. The adoption of each recommendation varied, but in 2013 approximately 50% of farmers reported treating all lame sheep within 3 days of onset of lameness (prompt treatment), 41% did not practice routine foot trimming, 50% culled sheep that had been lame and 14% vaccinated against footrot; all recommended best practices. The aim of this study was to investigate the prevalence of lameness in ewes in England from 2013 to 2015 and to identify changes in practice to manage lameness between 2013 and 2015 and the population attributable fraction for these managements.

A longitudinal study with a cohort of 154 English sheep farmers was run for three years, farmers completed questionnaires on lameness in their flock for the previous 12 months in 2013, 2014 and 2015. The geometric mean prevalence of lameness in ewes was 4.1% in 2015, significantly higher than 3.3% and 3.2% for the same 128 farmers who provided data in both 2013 and 2014. Between 2013 and 2015 there was a significant reduction in farmers practising prompt treatment (50.6%–28.6%) but an increase in not practising routine foot trimming (40.9%–79.2%), culling sheep that had been lame (49.4%–81.8%), and vaccinating against footrot (14.3%–29.2%).

Not practising prompt treatment, ≥5% of sheep feet bleeding during routine foot trimming, vaccinating ewes for <6 years or not vaccinating at all, and other flocks mixing with the flock, were associated with a significantly higher flock prevalence of lameness. Culling sheep that had been lame was not associated with prevalence of lameness. The population attributable fractions (PAFs) for not vaccinating for>5 years, not treating lame sheep promptly, ≥5% of sheep feet bleeding during routine foot trimming, and mixing of flocks were 34.5%, 25.3%, 2.9% and 2.4%. In 2013, when 50% of farmers used prompt treatment, the PAF for not using prompt treatment was only 13.3%. We conclude that the change in practice by these farmers towards flock-level managements and a reduction in individual prompt treatment of lame sheep negatively impacted the prevalence of lameness in sheep. This change occurred despite the evidence that prompt treatment of lame sheep is highly effective at reducing the prevalence of lameness in sheep flocks and is an example of cognitive dissonance.

Prevalence of lameness in sheep transported to meat processing plants in New Zealand and associated risk factors

Aims: To estimate the prevalence of lameness in sheep transported to meat processing plants in New Zealand, and to identify factors associated with the prevalence of lameness. Methods: The survey was conducted over the main meat processing season, running from October 2012 to the end of May 2013, at 10 sheep processing premises (five North Island and five South Island). A sample of 50 sheep selected from approximately six sheep consignments per week from each of the processing plants were scored for lameness, using a scale from Grade 1 (mild) to 3 (severe, non-weight-bearing). For each consignment the breed, age class and mean carcass weight were recorded. A multivariable regression model was fitted to identify the risk factors for prevalence of lame sheep (Grade 1-3) within a consignment. Results: In total, 1,854/78,833 (2.4 (95% CI = 2.2-2.5)%) sheep were diagnosed with lameness. Of the 1,854 lame sheep, lameness severity was Grade 1 in 1,349 (72.8%), Grade 2 in 450 (24.3%) and Grade 3 in 55 (3.0%) sheep. Within consignments ≥1 lame sheep was observed in 600/1,682 (35.7 (95% CI = 33.4-38.0)%) consignments. In Merino lambs and ewes the prevalence of lameness was greater than that of other breeds (p < 0.001), but in rams/wethers, the prevalence of lameness was lower in Merino than other breeds (p < 0.05). In sheep originating from the North Island, increasing mean carcass weight was associated with an increase in the prevalence of lameness (p < 0.001), but in the South Island prevalence was similar for different carcass weights (p = 0.5). In the North Island increasing yarding time was associated with an increase in the lameness prevalence (p < 0.01), but not in the South Island (p = 0.7). Sheep from the South Island generally had a higher prevalence of lameness than the North Island and the prevalence of lameness was lower over summer and autumn relative to the previous spring (p < 0.01). Conclusion: The results from this survey provided a measure of the prevalence of lameness in a section of the New Zealand sheep population, namely those animals sent for slaughter; as well as identification of several risk factors associated with lameness.

Analgesic effects of intravenous flunixin and intrafunicular lidocaine or their combination for castration of lambs

Objective

To analyse the effectiveness of intrafunicular lidocaine and intravenous flunixin for reducing pain and signs of stress in lambs undergoing surgical castration.

Design

Randomised controlled trial.

Setting

One university teaching hospital in Italy.

Participants

30 healthy male lambs, 9–12 weeks old.

Intervention

Allocation to five groups: a control group (C), undergoing general anaesthesia but not castration; a surgery group (S), undergoing orchiectomy without analgesic treatment; a surgery-lidocaine group (SL), undergoing orchiectomy and receiving intrafunicular 2 per cent lidocaine solution; a surgery-flunixin group (SF), undergoing orchiectomy and receiving intravenous flunixin; a surgery-flunixin-lidocaine group (SFL), undergoing orchiectomy and receiving both intrafunicular lidocaine and intravenous flunixin.

Main outcome measures

Nociception and stress were assessed through intraoperative indicators, serum cortisol concentration, glycaemia, behaviour, immune response and clinical evaluation of the heart rate (HR), respiratory rate and rectal temperature after surgery.

Results

Groups S and SL showed increased values of intraoperative HR, mean arterial pressure and postoperative cortisol concentration. In group SFL, cortisol values were similar to those of group C. No other difference could be detected.

Conclusions

The combination of intravenous flunixin and intrafunicular lidocaine reduced the pain and discomfort of lambs castrated under general anaesthesia. Intrafunicular lidocaine alone did not prevent pain or discomfort associated with castration.

Trial registration number

30/2012/CEISA/COM.

Ovine model of neuropathic pain for assessing mechanisms of spinal cord stimulation therapy via dorsal horn recordings, von Frey filaments, and gait analysis

Background

It is becoming increasingly important to understand the mechanisms of spinal cord stimulation (SCS) in alleviating neuropathic pain as novel stimulation paradigms arise.

Purpose

Additionally, the small anatomic scale of current SCS animal models is a barrier to more translational research.

Methods

Using chronic constriction injury (CCI) of the common peroneal nerve (CPN) in sheep (ovine), we have created a chronic model of neuropathic pain that avoids motor deficits present in prior large animal models. This large animal model has allowed us to implant clinical grade SCS hardware, which enables both acute and chronic testing using von Frey filament thresholds and gait analysis. Furthermore, the larger anatomic scale of the sheep allows for simultaneous single-unit recordings from the dorsal horn and SCS with minimal electrical artifact.

Results

Detectable tactile hypersensitivity occurred 21 days after nerve injury, with preliminary indications that chronic SCS may reverse it in the painful limb. Gait analysis revealed no hoof drop in the CCI model. Single neurons were identified and discriminated in the dorsal horn, and their activity was modulated via SCS. Unlike previous large animal models that employed a complete transection of the nerve, no motor deficit was observed in the sheep with CCI.

Conclusion

To our knowledge, this is the first reported large animal model of chronic neuropathic pain which facilitates the study of both acute and chronic SCS using complementary behavioral and electrophysiologic measures. As demonstrated by our successful establishment of these techniques, an ovine model of neuropathic pain is suitable for testing the mechanisms of SCS.

Development of a Pain Scoring System for Use in Sheep Surgically Implanted with Ventricular Assist Devices

Purpose/Aim: In prey species, such as sheep, clinical signs of postoperative pain can manifest in subtle ways or may be concealed entirely. Previous publications describing pain assessment in ruminants focus on lameness and flock behavior, often in a farm environment. These indicators of pain may be difficult to assess in sheep housed in biomedical research settings. We have developed a novel pain scoring system for sheep undergoing thoracotomy for implantation of ventricular assist devices that are permanently housed in modified stanchions. Materials and Methods: The pain scoring system includes ruminant-specific behavioral signs of pain in addition to objective measurements that can be readily evaluated in a biomedical research setting. A numerical score is generated by the evaluator for each category. A decision tree is utilized to help guide further action following the generation of a cumulative score by the evaluator. A total score of 0-2 requires no intervention, 3-9 requires the consideration of additional analgesic administration, and a pain score ≥ 10 warrants the consideration of additional multimodal analgesia. Results: A novel pain scoring system and decision tree specifically designed for sheep undergoing thoracotomy in a biomedical research environment was developed and successfully utilized. Out of 102 postoperative pain scores measured, 86 scores were <2. There were 17/102 postoperative pain scores ≥3, which typically resulted in the administration of supplemental rescue analgesia in the immediate postoperative period. Conclusions: A novel pain scoring system was developed and utilized in a biomedical research environment for evaluating postoperative pain in sheep undergoing thoracotomy for implantation of a ventricular assist device. Further studies are necessary to validate the reliability of this novel pain scoring system.

Evaluation of sampling frequency, window size and sensor position for classification of sheep behaviour

Automated behavioural classification and identification through sensors has the potential to improve health and welfare of the animals. Position of a sensor, sampling frequency and window size of segmented signal data has a major impact on classification accuracy in activity recognition and energy needs for the sensor, yet, there are no studies in precision livestock farming that have evaluated the effect of all these factors simultaneously. The aim of this study was to evaluate the effects of position (ear and collar), sampling frequency (8, 16 and 32 Hz) of a triaxial accelerometer and gyroscope sensor and window size (3, 5 and 7 s) on the classification of important behaviours in sheep such as lying, standing and walking. Behaviours were classified using a random forest approach with 44 feature characteristics. The best performance for walking, standing and lying classification in sheep (accuracy 95%, F-score 91%-97%) was obtained using combination of 32 Hz, 7 s and 32 Hz, 5 s for both ear and collar sensors, although, results obtained with 16 Hz and 7 s window were comparable with accuracy of 91%-93% and F-score 88%-95%. Energy efficiency was best at a 7 s window. This suggests that sampling at 16 Hz with 7 s window will offer benefits in a real-time behavioural monitoring system for sheep due to reduced energy needs.

Techniques for chronic monitoring of brain activity in freely moving sheep using wireless EEG recording

BACKGROUND

Large mammals with complex central nervous systems offer new possibilities for translational research into basic brain function. Techniques for monitoring brain activity in large mammals, however, are not as well developed as they are in rodents.

NEW METHOD

We have developed a method for chronic monitoring of electroencephalographic (EEG) activity in unrestrained sheep. We describe the methods for behavioural training prior to implantation, surgical procedures for implantation, a protocol for reliable anaesthesia and recovery, methods for EEG data collection, as well as data pertaining to suitability and longevity of different types of electrodes.

RESULTS

Sheep tolerated all procedures well, and surgical complications were minimal. Electrode types used included epidural and subdural screws, intracortical needles and subdural disk electrodes, with the latter producing the best and most reliable results. The implants yielded longitudinal EEG data of consistent quality for periods of at least a year, and in some cases up to 2 years.

COMPARISON WITH EXISTING METHODS

This is the first detailed methodology to be described for chronic brain function monitoring in freely moving unrestrained sheep.

CONCLUSIONS

The developed method will be particularly useful in chronic investigations of brain activity during normal behaviour that can include sleep, learning and memory. As well, within the context of disease, the method can be used to monitor brain pathology or the progress of therapeutic trials in transgenic or natural disease models in sheep.

A practical tool for locomotion scoring in sheep: reliability when used by veterinary surgeons and sheep farmers

A four-point locomotion scoring tool for sheep was developed and tested on 10 general practice veterinary surgeons (VS) and 10 sheep farmers. Thirty-four video clips of sheep displaying different locomotion scores were recorded and randomly assorted. Following a set period of training using four other video clips typical of the four locomotion scores, participants then scored the 34 test clips. The participants repeated the training and the exercise one month later. There were high levels of intraobserver repeatability: weighted κ (κW) 0.81 for VS and 0.83 for farmers. There was no difference in intraobserver repeatability between vets and farmers (Wilcoxon signed rank P=0.8). When considering the overall distribution of scores within the video package, there were high levels of interobserver repeatability: mean κW 0.73 for VS and 0.72 for farmers. However, the repeatability for the individual locomotion scores was only fair to moderate. It is therefore recommended that when observations are repeated on different occasions they are made by the same observer.

Repeated electrical stimulations as a tool to evoke temporal summation of nociceptive inputs in healthy, non-medicated experimental sheep

The nociceptive withdrawal reflex (NWR) model is used in animal pain research to quantify nociception. The aim of this study was to evaluate the NWR evoked by repeated stimulations in healthy, non-medicated standing sheep. Repeated electrical stimulations were applied at 5 Hz for 2s to the digital nerves of the right thoracic and the pelvic limbs of 25 standing sheep. The stimulation intensities applied were fractions (0.5, 0.6, 0.7, 0.8, 0.9 and 1) of the individual previously determined nociceptive threshold (It) after single stimulation. Surface-electromyographic activity (EMG) was recorded from the deltoid, the femoral biceps or the peroneus tertius muscles. The repeated stimulation threshold (RS It) was reached if at least one stimulus in the train was followed by a reflex with a minimal root-mean-square-amplitude (RMSA) of 20 μV. The behavioural reaction following each series of stimulations was scored on a scale from 0 (no reaction) to 5 (vigorous whole-body reaction). For the deltoid muscle, RS It was 2.3 mA (1.6-3 mA) with a reaction score of 2 (1-2) and at a fraction of 0.6 (0.5-0.8)×It. For the biceps femoris muscle, RS It was 2.9 mA (2.6-4 mA) with a reaction score of 1 (1-2) at a fraction of and 0.55 (0.4-0.7)×It while for the peroneus tertius muscle RS It was 3 mA (2.8-3.5 mA) with a reaction score of 1 (1-2) and at a fraction of 0.8 (0.8-0.95)×It. Both, RMSA and reaction scores increased significantly with increasing stimulation intensities in all muscles (p<0.001). The repeated application of electrical stimuli led to temporal summation of nociceptive inputs and therefore a reduction of the stimulus intensity evoking a withdrawal reaction in healthy, standing sheep. Data achieved in this study can now serve as reference for further clinical or experimental applications of the model in this species.

Assessment of biometric tools for quantitative gait analysis in Holstein calves

OBJECTIVE

To assess biometric tools for gait analysis in healthy calves by use of pressure mat sensors, a handheld algometer, and serial circumferential measurements of selected joints.

ANIMALS

20 six- to eight-week-old healthy male Holstein calves.

PROCEDURES

Calves were evaluated over a 4-day period. Gait analysis was performed by training calves to walk over a pressure-sensitive mat, which recorded quantitative measurements. An algometer was applied perpendicular to each joint until an aversion response was observed or a preset limit of 50 N/cm(2) was obtained. Circumference measurements of the carpal and tarsal joints were obtained by the application of a flexible measuring tape to defined areas of each limb. Variability between joint circumference measurements and pressure mat variables were analyzed with a standard least squares means model. Algometer measurements were dichotomized, and logistic regression was used to assess the probability that a calf reacted to algometer-applied pressure.

RESULTS

1 calf was removed from the study because of lameness. Mean carpal and tarsal joint circumference measurements were reliable and consistent among calves. Algometry results suggested that healthy calves were more sensitive to pressure applied to the elbow and stifle joints, compared with pressure applied to the carpal, tarsal, and metacarpophalangeal or metatarsophalangeal joints. Pressure mat variables of stance time and stride velocity varied greatly among calves, whereas impulse and maximum forces varied little.

CONCLUSIONS AND CLINICAL RELEVANCE

Findings can serve as reference points for other studies and be used for comparison with results for calves with lameness or altered gaits.

Dynamics and impact of footrot and climate on hoof horn length in 50 ewes from one farm over a period of 10 months

Footrot, including interdigital dermatitis, is caused by Dichelobacter nodosus cause the majority of lameness in sheep in the UK. Lame sheep often have overgrown hoof horn but recent evidence has indicated that trimming overgrown hoof horn increases recovery time, and that routine foot trimming of the flock does not reduce the prevalence or incidence of lameness. The objectives of this study were to investigate the temporal associations between hoof horn length, footrot and climate. Fifty multiparous ewes were monitored for 10 months. On eight occasions hoof horn length, foot lesions and body condition were recorded. At the first examination, ewes were assigned to one of two treatment groups. All ewes that became lame with footrot were treated at one time point per week, either by trimming hoof horn and applying a topical antibiotic spray or with parenteral antibiotic and topical antibiotic spray.

Hoof horn length in ewes at pasture varied over the year and was associated with temperature and rainfall. New cases of footrot occurred all year round and were associated with prior prevalence of footrot in the flock and prior temperature and rainfall. Overgrown hoof horn did not precede lameness but occurred once the sheep were lame. One year of prompt treatment of footrot reduced the range in hoof horn length in the sheep in both treatment groups. At the end of the study the hoof lengths of ewes in both groups were not significantly different. On this farm, hoof horn length was self-regulating in both non-lame and treated lame sheep whether trimming was part of the treatment or not and there would have been no benefit from routine foot trimming of this flock.

Thermal nociceptive threshold testing detects altered sensory processing in broiler chickens with spontaneous lameness

Lameness is common in commercially reared broiler chickens but relationships between lameness and pain (and thus bird welfare) have proved complex, partly because lameness is often partially confounded with factors such as bodyweight, sex and pathology. Thermal nociceptive threshold (TNT) testing explores the neural processing of noxious stimuli, and so can contribute to our understanding of pain. Using an acute model of experimentally induced articular pain, we recently demonstrated that TNT was reduced in lame broiler chickens, and was subsequently attenuated by administration of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs). This study extended these findings to a large sample of commercial broilers. It examined factors affecting thermal threshold (Part 1) and the effect of an NSAID drug (meloxicam, 5 mg/kg) and of an opioid (butorphanol; 4 mg/kg) (Part 2). Spontaneously lame and matched non-lame birds (n=167) from commercial farms were exposed to ramped thermal stimulations via a probe attached to the lateral aspect of the tarsometatarsus. Baseline skin temperature and temperature at which a behavioural avoidance response occurred (threshold) were recorded. In Part 1 bird characteristics influencing threshold were modelled; In Part 2 the effect of subcutaneous administration of meloxicam or butorphanol was investigated. Unexpectedly, after accounting for other influences, lameness increased threshold significantly (Part 1). In Part 2, meloxicam affected threshold differentially: it increased further in lame birds and decreased in non-lame birds. No effect of butorphanol was detected. Baseline skin temperature was also consistently a significant predictor of threshold. Overall, lameness significantly influenced threshold after other bird characteristics were taken into account. This, and a differential effect of meloxicam on lame birds, suggests that nociceptive processing may be altered in lame birds, though mechanisms for this require further investigation.

The radiographic anatomy of the normal ovine digit, the metacarpophalangeal and metatarsophalangeal joints

The aim of this project was to develop a detailed, accessible set of reference images of the normal radiographic anatomy of the ovine digit up to and including the metacarpo/metatatarsophalangeal joints. The lower front and hind limbs of 5 Lleyn ewes were radiographed using portable radiography equipment, a digital image processer and standard projections. Twenty images, illustrating the normal radiographic anatomy of the limb were selected, labelled and presented along with a detailed description and corresponding images of the bony skeleton. These images are aimed to be of assistance to veterinary surgeons, veterinary students and veterinary researchers by enabling understanding of the normal anatomy of the ovine lower limb, and allowing comparison with the abnormal.

Nociceptive responses to thermal and mechanical stimulations in awake pigs

BACKGROUND

Porcine skin exhibits a high degree of homology to human skin, and the pig has recently been used as a cutaneous pain model. However, before the full potential of this novel in vivo cutaneous pain model can be achieved, several methodological aspects related to the management of awake animal studies in a large species require further examination. This manuscript describes the initial development of a porcine model of cutaneous nociception and focuses on interactions between the sensory modality, body size and the anatomical location of the stimulation site.

METHODS

Pigs of different body sizes (30 and 60 kg) were exposed to thermal (CO2 laser) and mechanical (pressure application measurement device) stimulations to the flank and the hind legs in a balanced order. The median response latency and the type of behavioural response were recorded.

RESULTS

Small pigs exhibited significantly lower pain thresholds (shorter latency to response) than large pigs to thermal and mechanical stimulations. Stimulations at the two anatomical locations elicited very distinct sets of behavioural responses, with different levels of sensitivity between the flank and the hind legs. Furthermore, small animals exhibited lower levels of individual variability between single stimulations.

CONCLUSIONS

Our data indicate that this experimental approach may be valuable for use in studies that focus on porcine cutaneous nociception.

The effects of farming system and season on the prevalence of lameness in sheep in northwest Iran

AIMS

To determine the prevalence of lameness in sheep in Urmia, northwest Iran, and compare the effects of production system and season on prevalence.

METHODS

A cross-sectional study, using cluster sampling, was conducted. The selected flocks included 18 with 2,315 sheep from farmed production and 28 with 7,619 sheep from semi-migratory systems, and were visited once in summer (grazing season) and once in winter (housing season). Sheep showing signs of lameness were examined to detect the causes of lameness. Bacteriology and histopathology were also performed if required.

RESULTS

The probability of overall lameness was not affected by farming system (p = 0.40), but in the grazing season was less (OR = 0.62; 95% CI = 0.56-0.69) than in the housing season. Footrot was most the common cause of lameness, occurring in 1,047/1,880 (56%) cases. Among flocks, 40/46 (87%) had ≥ 1 case of footrot. Farming system had no effect on occurrence of footrot (p = 0.85), but the probability of footrot in the grazing season was less (OR = 0.21; 95% CI = 0.18-0.25) than in the housing season. Semi-migratory flocks had less hoof overgrowth (OR = 0.30; 95% CI = 0.16-0.56) than farmed flocks, and the probability of hoof overgrowth in the grazing season was less (OR = 0.19; 95% CI = 0.12-0.29) than in the housing season. The probability of digital abscess was less in semi-migratory flocks (OR = 0.64; 95% CI = 0.46-0.88) than farmed flocks, and in the grazing season was more (OR = 2.14; 95 CI = 1.61-2.85) than in the housing season. The probability of interdigital gland infection was higher (OR = 7.15; 95% CI = 5.36-9.55) in the grazing season than in the housing season. Staphylococcus aureus was isolated from 9/11 (82%) sheep affected with interdigital gland infection.

CONCLUSIONS

Footrot was the main cause of lameness in sheep in both farmed and semi-migratory farming systems in this study, especially in the housing season. In the grazing season, digital abscess and interdigital gland infection should be considered as common causes of sporadic lameness in sheep.

CLINICAL RELEVANCE

In practice, lameness in sheep can be a major concern both in farmed and semi-migratory farming systems, with a high occurrence in the housing season. Footrot was a main cause of lameness in sheep in northwest Iran.

Co-induction of cyclooxygenase-2 [correction of cyclooxyenase-2] and early growth response gene (Egr-1) in spinal cord in a clinical model of persistent inflammation and hyperalgesia

BACKGROUND

This study characterised the effects of persistent peripheral inflammation of the foot on pain and spinal cord expression of cyclooxygenase-1 and -2 (COX-1 and COX-2) and early growth response gene 1 (Egr-1), known markers of neuronal plasticity, in a clinical model of naturally-occurring inflammatory disease and hyperalgesia in sheep ('footrot'), before and after routine treatment (parenteral treatment with antibiotics and antiseptic footbathing). The temporal pattern of expression of COX-1, COX-2 and Egr-1 mRNA and protein were analysed using real-time PCR and Western blotting.

RESULTS

Animals affected with persistent peripheral inflammation displayed significant hyperalgesia and lameness (a proxy indicator of spontaneous pain) restricted to the inflamed limb. Hyperalgesia and lameness were significantly attenuated 1 day after treatment, and resolved further by day 7 and day 3, respectively. COX-2 but not COX-1, protein expression was up-regulated in spinal cord from lame animals on day 0, before treatment. Following treatment and attenuation of pain behaviours, levels of COX-2 returned to control levels. Significant induction of Egr-1 mRNA and protein were observed in spinal cord from lame animals. Three days after treatment, levels of Egr-1 mRNA returned to control levels, however, Egr-1 protein remained elevated.

CONCLUSION

Elevated levels of spinal COX-2 and Egr-1 protein correlate with the presence of pain and hyperalgesia, and may underlie persistent pain, although a direct causal link has still to be established. Understanding the temporal pattern of expression of key mediators in clinical pain states may lead to better strategies to manage pain.

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

OBJECTIVE

To investigate whether events that may be stressful to young lambs, including simulated infection or social isolation, modulate pain experienced by lambs following castration and tail docking (C/D).

STUDY DESIGN

Randomised, controlled, prospective study.

ANIMALS

Fifty male lambs born to 46 second-parity Mule ewes.

METHODS

Lambs were allocated randomly to one of four groups, experiencing either a potential stressor or handling on day 2 after birth, followed by C/D or handling only on day 3. Quantitative sensory testing (QST) data [mechanical nociceptive thresholds (MNT), Semmes Weinstein filaments (SW), response to cold] and serum cortisol concentration were measured at time points after application of treatments to lambs on days 2 and 3 after birth. The treatment groups were LPS, injection of bacterial lipopolysaccharide IV on day 2, C/D on day 3; ISOL, isolation from the dam for 10 minutes on day 2, C/D on day 3; CAST, handling only on day 2, C/D on day 3; CONT, handled only on days 2 and 3.

RESULTS

Castration and tail docking caused transient hypoalgesia as measured by MNT and SW. Simulated infection and isolation caused hyperalgesia 3 hours after application, indicated by a reduction in MNT, however they did not alter the pain response to C/D compared to lambs in the CAST group. Injection of LPS and C/D caused increased serum cortisol concentration. The magnitude of the cortisol response to C/D was not altered by prior exposure to either LPS or isolation.

CONCLUSIONS AND CLINICAL RELEVANCE

LPS and isolation did not modulate the response to C/D but did cause hyperalgesia. This highlights the importance of flock health management and husbandry techniques to reduce the incidence of either systemic infection or psychological stressors in young lambs.

Pain and analgesia in domestic animals

The biggest challenge to the use of analgesic agents in animals is the determination of the efficacy of these agents. In humans, the verbal communication of the alleviation of pain is fundamental to the effective use of analgesics. In animals, the lack of verbal communication not only confounds the diagnosis and characterisation of the experience of pain, but also challenges the evaluation of the analgesic therapy. As animals possess the same neuronal pathways and neurotransmitter receptors as humans, it seems reasonable to expect that their perceptions of painful stimuli will be similar, and this is a basis for the use of laboratory animals for screening of analgesics for human use. However, as the evaluation in the laboratory animal tests is based mainly on behavioural responses, and although some physiological responses do occur, it is often difficult to separate these from stress responses. The use of behavioural responses to evaluate analgesics in a range of species is complicated by the fact that different species show different behaviours to a similar pain stimulus, and different pain stimuli produce different pain responses in the same species. Thus behaviours may be species- and pain-specific and this can complicate analgesic evaluation. As most animals possess similar neuronal mechanisms to humans for pain perception, it is not surprising that the standard human pain control strategies can be applied to animals. For instance, local anaesthetics, opioids, non-steroidal anti-inflammatory drugs (NSAIDs), as well as other analgesics used in humans are all found to be effective for animal use. Differences in metabolism and distribution between various species, as well as financial considerations in larger animals can affect efficacy and thus limit their use. In addition, the use of any drug in a species that may be intended for human consumption will be limited by residue considerations. The treatment of pain in animals presents many challenges, but the increasing public concerns regarding animal welfare will ensure that studies into the nature and control of animal pain will continue to have a high profile.

Animal-based measurements of the severity of mastitis in dairy cows

A range of clinical parameters were studied to assess their usefulness as objective markers of the severity of clinical mastitis in dairy cows. Cows with moderate clinical mastitis had significantly higher rectal temperatures and heart and respiratory rates than cows with mild clinical mastitis or control cows. The difference in temperature between quarters did not vary significantly between the control cows and the cows with mastitis, but there was a larger difference between quarter temperatures in the cows with moderate mastitis than in the cows with mild mastitis or the control cows. The hock-to-hock distance in the control cows was significantly smaller than in the cows with mild to moderate mastitis, but there was no significant difference in the distance either between the cows with mild mastitis and those with moderate mastitis, or between the cows with mastitis in the front quarters and those with mastitis in the hind quarters. The mechanical threshold to pain of the cows with mild and moderate mastitis was significantly lower than that of the control cows.

The inter- and intra-observer reliability of a locomotion scoring scale for sheep

A seven point locomotion scoring scale, ranging from 0=normal locomotion to 6=unable to stand or move, has been developed. To test the between and within observer reliability of the scale, 65 movie clips of sheep with normal and varying degrees of abnormal locomotion were made. Three observers familiar with sheep locomotion were trained to read the movie clips. Thirty clips were randomly selected and used to test between and within observer agreement. There was high inter-(intra-class correlation coefficient [ICC]=0.93, weighted kappa [kappa(w)]=0.93) and intra-(ICC=0.90, kappa(w)=0.91) observer reliability, with no evidence of observer bias. The main between score differences were for scores 0 (normal) and 1 (uneven posture and shortened stride but no head movement). The results indicate that the locomotion scoring scale using groups of defined observations for each point on the scale was reliable and may be a useful research tool to identify and monitor locomotion in individual sheep when used by trained observers.

Total knee replacement: is it really an effective procedure for all?

Total knee replacement (TKR) is considered an effective intervention for the treatment of chronic knee pain and disability. Yet there is increasing evidence, based on research using patient-based outcome measures, that a significant proportion of patients experience chronic knee pain, functional disability, a poor quality of life and dissatisfaction after TKR. Although some poor outcomes after TKR are due to surgical technique and implant factors, much of the pain and disability after surgery is medically unexplained. A range of possible patient factors could contribute to a poor outcome after TKR. Socio-demographic factors that have been found to correlate with a poor outcome after TKR include female gender, older age and low socio-economical status. Medical factors that are highly predictive of pain and disability after TKR are a greater number of co-morbidities and a worse pre-operative status. A range of psychological factors could be predictive of a poor outcome after surgery including depression, low self-efficacy, poor pain coping strategies, somatization, low social support and patient expectations. It is also proposed that a biological explanation for continuing pain after TKR could involve central sensitisation, a dysfunction of pain modulation by the central nervous system. To improve patient selection for TKR, future research needs to focus on developing a pre-operative screening protocol to identify those patients at risk of medically unexplained pain and disability after TKR.

Evaluation of the use of thermal thresholds to investigate NSAID analgesia in a model of inflammatory pain in cats

This study evaluated thermal threshold (TT) testing for investigation into NSAID analgesia in cats. Seven cats participated in two crossover studies. TTs were measured on thoracic skin using a device developed specifically for cats. Skin temperature was recorded, then the heater activated. At the behavioural end point heating was stopped and temperature (=TT) recorded. In part 1, TTs were measured following subcutaneous (SC) ketoprofen or saline. In part 2, the process was repeated after intradermal kaolin induced mild inflammation at the test site. TTs were measured before treatment and two hourly for 24 h. In part 1, skin temperature did not change but in part 2 it increased more after saline than ketoprofen. TT did not change significantly after any treatment. However, after ketoprofen TT fell below the 95% confidence interval (CI) in part 1 and increased above it in part 2. The method detected some NSAID effects but is unlikely to be sufficiently sensitive for study of NSAID analgesia.

Carprofen and buprenorphine prevent hyperalgesia in a model of inflammatory pain in cats

A model of nociceptive threshold determination was developed for evaluation of NSAID analgesia in cats. In a crossover study, eight cats received carprofen (4 mg/kg), buprenorphine (0.01 mg/kg) or saline (0.3 ml) subcutaneously before intradermal kaolin injection on the antebrachium to induce mild inflammation. Pressure thresholds were measured at the injected site using blunt-ended pins advanced by manual inflation of a bladder within a bracelet. Bladder pressure was recorded as threshold (PT) at the behavioural end point. Baseline PT were recorded before kaolin injection (time 0). PT was measured at 2-10 h intervals for 52 h. PT below the lower 95% confidence interval (CI) of baseline values indicated hyperalgesia. After saline, hyperalgesia was detected from 2-6 h, 22-26 h, and at 30 and 36 h. After carprofen, PT remained within the 95% CI. After buprenorphine, PT remained within the 95% CI except at 2h. Carprofen and to some extent buprenorphine, prevented inflammatory hyperalgesia.

Effect of lameness on estrous behavior in crossbred cows

Lameness, a common disease in crossbred dairy cows, badly affects their fertility. To elucidate, if estrous behavior, comprising of duration and expression of certain estrous behavioral sign(s) (EBS), is involved, an estrous expression score system was applied to objectively compare estrous behavior during 27 and 58 estrous periods, respectively, in 17 normal and 37 lame cows kept in a group of 200 cows under loose housing system in tropical India. The cows were detected in estrus and were closely watched daily for 30 min at 0630, 1030, 1430 and 1830 h from the beginning to the end of estrus. The duration of estrus was similar in the normal and the lame cows (18.7+/-1.2 h versus 17.2+/-0.9 h) and almost similar EBS were shown by two types of cows, albeit with varying frequency. Standing to be mounted, the highest ranking EBS was shown by equal proportions of the cows in both the groups (76.4% versus 73.0%). A lower proportion of lame cows showed head side mounting (35% versus 53%; P<0.05). The frequency of standing to be mounted events was lower in the lame than in the normal cows (2.4+/-0.4 versus 8.0+/-2.5; P<0.05). The lame cows earned non-significantly lower than normal estrous behavior score (1100+/-179 versus 1610+/-357). Further, the presence of more than one cow simultaneously in estrus enhanced the estrous behavior score in the normal (406.4+/-63.0 for one cow in estrus versus 793.0+/-146.0 for three cows simultaneously in estrus; P<0.05), but not in the lame cows. Lameness appeared to have suppressed the playful behavior during estrus probably owing to pain related stress. It is concluded that mildly lame cows appear to have normal physiological estrus. However, some of the EBS remain subdued which prone them to remain undetected for timely breeding.

Comparison of perioperative analgesic protocols for dogs undergoing tibial plateau leveling osteotomy

OBJECTIVE

To compare effects of 3 commonly used perioperative analgesic protocols (epidural injection, intra-articular injection, and intravenous [IV] injection) for management of postoperative pain in dogs after tibial plateau leveling osteotomy (TPLO).

STUDY DESIGN

Prospective, randomized clinical trial.

ANIMALS

Fifty-six healthy dogs with naturally occurring cranial cruciate ligament rupture.

METHODS

Dogs were premedicated with IV hydromorphone and acepromazine and were randomly assigned to receive either E (preoperative epidural injection with morphine and bupivacaine), IA (pre- and postoperative intra-articular injections of bupivacaine), or C (neither epidural morphine and bupivacaine, nor intra-articular bupivacaine). All dogs were administered hydromorphone (0.05 mg/kg IV) at extubation and as needed to maintain comfort postoperatively. Patients were observed and monitored continuously for 24 hours and discomfort was assessed using visual analog pain scores (VASs), multifactorial pain scores (MPSs), and response to a pressure nociceptive threshold (PNT) measuring device. Time to 1st dose and the total doses of hydromorphone required to achieve adequate comfort for each dog were recorded.

RESULTS

No differences in measured indices of postoperative pain were observed between dogs of each treatment group; VAS (P=.190), MPS (P=.371), and PNT (P=.160). Time to 1st analgesic intervention was longer for Group E compared with Group C (P=.005) and longer for Group IA compared with Group C (P=.032). Although time to 1st intervention between Groups E and IA were longer for Group E, differences were not significant. To provide an adequate level of comfort, more analgesic interventions were administered to dogs in Group C compared with dogs in group E (P=.015). On average, more hydromorphone was administered to Group C compared with Group IA (P=.072) and to Group IA compared with Group E (P=.168), but statistical significance was not reached for these data.

CONCLUSIONS

In this study population, significant differences were seen in time to 1st hydromorphone dose between Groups E and IA compared with Group C. As well, more supplemental analgesia was administered to Group C compared with Group E to maintain the same level of postoperative comfort. Although differences between Groups E and IA tended to favor the epidural group, differences were minimal and not statistically significant.

CLINICAL RELEVANCE

Our results suggest that regardless of analgesic protocol, measured indices of pain in dogs after TPLO can be minimized if dogs are continuously observed and appropriately supplemented with parenteral opioids. However, the frequency of postoperative opioid dosing can be minimized and may be a factor when contemplating supplementary use of epidural or intra-articular injections as part of a balanced analgesic approach.

Pain Detection and Amelioration in Animals on the Farm: Issues and Options

Pain in nonhuman animals is a difficult concept to identify and measure. This article briefly describes the consequences of pain in animals on the farm and explains the reasons for the minimal use of analgesics in farmed animals. Pain can have implications for both animal welfare and economics. The reasons for a low use of analgesics in farmed animals include the lack of recognition of animal pain owing to the apparent lack of anthropomorphically identifiable behavioral changes, concern over human food safety, and lack of research efforts to develop safe analgesics for farm use. Treatment cost relative to the benefits expected is another hindering factor. Interventions to minimize pain must begin with developing objective and practical measures for pain identification and measurement at the farm level. A suggested use of a combination of different behavioral and physiological indicators would help to identify pain in animals. To facilitate continued usage of the methodologies on the farm it also is necessary to evaluate the economic implication of the pain alleviation intervention.

The management and welfare of some common ovine obstetrical problems in the United Kingdom

This review approaches sheep welfare during the periparturient period from a veterinary practitioner viewpoint. At the most fundamental husbandry level, the general hygiene standards adopted on many sheep farms in the United Kingdom (UK) during the lambing period are unacceptable and require urgent improvement. Concerns also arise from obstetrical conditions attended by farmers which cause pain that can be identified using clinical criteria such as altered demeanour and behaviour of the ewe, and the presence of inflammation of the reproductive tract. Reduced production is evidenced by poor milk production and hungry lambs, the necessity to rear such lambs artificially and, in neglected cases, death of the ewe and her lambs. The correction of dystocia, periparturient vaginal, uterine and rectal prolapses is greatly facilitated after epidural injection of lignocaine, or a combination of xylazine and lignocaine administered by a veterinary surgeon. However, the perceived high professional fees charged for these services, and for Caesarean operations, result in few sheep receiving veterinary care, with such neglect directly contributing to poor welfare standards and an increased ewe mortality rate during the periparturient period. Whilst ending any welfare concern, the destruction of ewes rather than requesting veterinary services purely for economic reasons is a disturbing trend in sheep production in the UK and raises concerns regarding positive interaction between veterinary practitioner and farmer. In this article, veterinary treatments which provide effective analgesia are described and costed for obstetrical conditions in sheep. Recommended treatment protocols are described for the common obstetrical problems in sheep. In addition to appropriate treatment of obstetrical problems and alleviation of pain, if veterinary involvement could reduce ewe periparturient mortality from estimated figures of 4-2% this would save an estimated 400,000 ewes annually in the UK. Sheep welfare could be considerably improved by practising veterinarians providing practical instruction to small groups of clients with funding provided by government agencies.

Chronic stress in sheep: assessment tools and their use in different management conditions

Chronic stress occurs when animals are unable to deal with a persistent stressor with species-typical responses, or when several stressors are present concurrently. Chronic stress is most frequently considered in intensive systems, but it may also be a welfare concern for extensively managed species, such as the sheep. Here we review behavioural and physiological responses of sheep to experimentally induced chronic stressors to determine relevant indicators of chronic stress. Neuroendocrine responses to chronic stress are difficult to interpret because initial responses are followed by an apparent normalisation. Thus, cortisol or catecholamines may be at or below pre-stress levels during chronic stress, but this varies with different stressors. Chronic stress can also affect reproductive function, impair body and wool growth and meat quality, reduce immune function, and is associated with greater parasite burdens in sheep. Chronic stress induces alterations in behaviour patterns, particularly activity and feeding, and circadian rhythms of behaviour. Stereotypic behaviours, however, are infrequent in sheep and may occur only in experimental conditions of social isolation. Behavioural and physiological data suggest that rough handling and sheepdogs may be sources of chronic stress for sheep. Social subordination and weaning also act as chronic stressors, leading to higher parasitism in these animals and a greater response to additional stressors. Lameness and parasitism are associated with physiological and behavioural responses indicating that these are severe forms of chronic stress in sheep. It is unclear whether environmental stressors, such as weather and food availability, induce chronic stress in sheep. Under-nutrition may, however, be a welfare concern through its impact on lamb survival. The existence of many sources of chronic stress in the management of sheep suggests that the welfare of this species requires more attention than it has currently received.

Tail docking in dogs: a review of the issues

Different groups in our community hold strong views about tail docking in domestic dogs. These range from veterinary associations and welfare organisations, which typically want the practice banned, to purebred dog associations, which vigorously oppose the introduction of antidocking legislation. An evaluation of the tail docking issue, which is informed and nonemotive, requires the integration of moral views with biological and behavioural facts. In recent years, much data have been accumulated concerning the welfare implications of tail docking. Unfortunately, however, there has been limited transfer of this knowledge to people interested in the issue. In this review some of the main arguments for and against canine tail docking are presented and evaluated.

Up-regulation of metabotropic glutamate receptor subtypes 3 and 5 in spinal cord in a clinical model of persistent inflammation and hyperalgesia

Evidence from experimental pain research has revealed that metabotropic glutamate receptors (mGluRs) play a pivotal role in nociceptive processing, inflammatory pain and hyperalgesia. The aim of this study was to characterise expression of group I and II mGluRs in spinal cord in a model of naturally occurring persistent inflammation (sheep with unilateral lameness due to inflammation of the digital tissues of the feet, estimated to have been affected by the condition for >2 weeks) and an experimental model of acute inflammation (injection of intradermal carrageenan into lower forelimb in sheep). Animals with unilateral clinical inflammation displayed significant mechanical hyperalgesia on the affected limb. Carrageenan treatment produced significant bilateral limb mechanical hyperalgesia 3 h post-injection. Up-regulation of mGluR(3) and mGluR(5) mRNA was observed in ipsilateral spinal cord recovered from clinically lame animals, restricted to laminae II-V and I-II, respectively. Western blot analyses of protein extracts revealed a bilateral increase in mGluR(2/3) and mGluR(5). No change was detected in spinal cord mGluR(1) or mGluR(2) mRNA. There was no change in mGluR(1,2,3,5) subtype mRNA or proteins in spinal cord recovered from animals 3 h post-carrageenan. These results demonstrate for the first time that mGluR subtypes are differentially expressed in spinal cord dorsal horn in response to persistent inflammation, and suggest that mGluR activity may be involved in mediating altered behaviours associated with clinical inflammatory pain.