Bristol Rabbit Pain Scale (BRPS): clinical utility, validity and reliability

Background

The Bristol Rabbit Pain Scale (BRPS) was developed using a combination of methods, focus groups and behavioural observation, that led to a composite pain scale of six categories (Demeanour, Locomotion, Posture, Ears, Eyes and Grooming) with four intensities of pain (0, 1, 2, and 3), and a total score of 0–18. The aim of this study was to assess the clinical utility, validity and reliability of the BRPS.

Materials and methods

The clinical utility of the BRPS was tested using a questionnaire composed of ten questions each on a five-point Likert scale ranging from one (strongly disagree) to five (strongly agree). The respondents, (veterinary surgeons and veterinary nurses), were asked to assess up to four rabbits in acute pain, using the novel pain. They then completed the questionnaire which asked whether the BRPS was easy and quick to use and whether it provided information that was clinically useful. The questionnaire was tested for internal reliability using the Cronbach’s alpha reliability coefficient. The construct validity (how well the tool measures the concept it was designed for) was measured by observers blindly rating 20 rabbits pre- and post-surgery whilst the criterion validity (the degree to which the tool correlates with a gold standard) was assessed by correlating BRPS scores with scores using a numerical rating scale (NRS) with a total score of 0–10. Inter-rater reliability was tested by quantifying the agreement in the pain scores given by nine participants when assessing the same 40 video clips. The intra-rater reliability was measured by testing how consistent the participants were when rating the same clips one month later.

Results

The median score of the ten questions of the clinical utility test was 4 (range 2–5). The Cronbach’s alpha reliability coefficient of the clinical utility test was good (α = 0.811) demonstrating good internal consistency. The median (range) pain score of the BRPS and the NRS were 3 (0–14) and 0 (0–8) before surgery and 12 (1–18) and 7 (0–10) after surgery respectively. The BRPS demonstrated high construct validity (Z = -11.452; p < 0.001) and there was a strong correlation between the BRPS and the NRS (Rho = 0.851; p < 0.001) indicating high criterion validity. The inter-rater and the intra-rater agreements were α = 0.863 and α = 0.861 respectively, which is considered good.

Conclusions

This study showed that the BRPS is a suitable tool for quantifying pain in rabbits in a clinically useful, valid and reliable way.

Post-operative nausea and vomiting (PONV) observed in a clinical study designed to assess the analgesic effects of intravenous and subcutaneous methadone in dogs

Opioids are a key component of multimodal analgesia. Methadone is licensed in Europe for IV, IM and SC use in dogs despite there being no published studies assessing the analgesic efficacy of SC administration. Our intention was to compare the analgesic effect of IV or SC methadone. Fifteen dogs presenting for stifle surgery were administered 0.4mg/kg methadone IV followed by a randomised 0.4mg/kg methadone IV or SC dose 3h later. All dogs received ultrasound-guided sciatic and saphenous nerve blocks with bupivacaine prior to surgery. This protocol resulted in opioid adverse effects (hypersalivation, vomiting and/or regurgitation) in 5/15 dogs (33%). Thus, in consultation with the ethical review committee, an otherwise identical protocol using a revised 0.2mg/kg methadone dose was implemented. In the next three dogs studied, similar opioid adverse effects were found in all three dogs and the study was terminated. This paper highlights the potential for post operative nausea and vomiting (PONV), which may have been induced by methadone when used in combination with efficacious locoregional anaesthesia.

Influence of peri-incisional epaxial muscle infiltration with bupivacaine pre- or post-surgery on opioid administration in dogs undergoing thoraco-lumbar hemilaminectomy

This study investigated the influence of bupivacaine infiltration before or after hemilaminectomy on peri-operative opioid requirement in dogs. Thirty dogs undergoing T3-L3 hemilaminectomy were randomly assigned to receive peri-incisional infiltration of bupivacaine 2 mg/kg into the epaxial muscles before surgery (Group A), at wound closure (Group B), or no infiltration (Group C). Anaesthesia comprised dexmedetomidine 4 mcg/kg and methadone 0.3 mg/kg IV (premedication), alfaxalone IV (induction), and isoflurane in oxygen (maintenance). All dogs received meloxicam SC/PO prior to induction of general anaesthesia. Response to surgery, defined as a change in autonomic physiological variables >20% above baseline, was treated with fentanyl 2.5 mcg/kg boluses, followed by a continuous rate infusion of fentanyl at 5 mcg/kg/h. The Glasgow Composite Pain Score-Short Form (GCPS-SF) was performed before premedication and at regular intervals until 24 h postoperatively. Methadone 0.2 mg/kg analgesia was given IV if GCPS-SF was ≥5/20. Number of intraoperative, postoperative and total analgesic interventions were recorded. Analgesic interventions were analysed using a chi-squared test using a Pocock approach and statistical significance was set at P < 0.029. The number of intra-operative analgesic interventions in Group A (median, 0; range, 0-2), was significantly lower than in Group B (median, 3; range, 0-5) and Group C (median, 3; range, 0-5; P = 0.019). Regarding postoperative interventions, there were significantly fewer in Group A (median, 0; range, 0-1) and Group B (median, 0; range, 0-1) than in Group C (median, 1; range, 0-2; P = 0.047). Group A (median, 0; range, 0-3), had significantly fewer total analgesic interventions than Group B (median, 3; range, 0-6) and Group C (median, 4; range, 1-7; P = 0.014). Bupivacaine reduced peri-operative opioid administration and pre-surgical peri-incisional infiltration yielded the greatest benefit.

Pain and analgesia in pet rabbits: a survey of the attitude of veterinary nurses

OBJECTIVES

To gain insight into veterinary nurse knowledge of pain recognition and control in rabbits.

MATERIALS AND METHODS

We used a survey to establish current attitudes amongst veterinary nurses towards pain management in pet rabbits and factors that might shape those attitudes. The survey was advertised at national and international veterinary conferences, in veterinary publications and on social media.

RESULTS

A total of 284 questionnaires (95% from the UK) were completed and analysed. The majority of respondents (78%) nursed 1-10 rabbits per month and 5.6% of the respondents reported regularly running a rabbit clinic. The respondents were regularly involved in nursing during common procedures such as castration and ovariohysterectomy. Responsibility for post-operative pain assessment was reported to be by "nurses only" (50%), "nurses and vets" (42%) and occasionally by "vets only" (3%). The majority of respondents reported that they did not use a pain scale but often relied on behavioural indicators, while 20% used the Rabbit Grimace Scale. The majority of the respondents reported being "fairly confident" at recognising pain in rabbits.

CLINICAL SIGNIFICANCE

Veterinary nurses are involved in many aspects of rabbit care, and they are generally confident at nursing this species. This survey also suggests the need for more data on the use of pain assessment tools in rabbits and the importance of teamwork between nurses and veterinarians.

Ice therapy: cool, current and complicated

This is the fourth Capsule review article provided by the WSAVA Global Pain Council and which discusses the use of ice or cold therapy as a non-pharmacologic modality for pain control in small animal practice. The physiological effects of cold therapy on tissues, receptors and ion channels are discussed; as well as indications, recommendations for, and limitations of use.

Intraperitoneal and incisional analgesia in small animals: simple, cost-effective techniques

The World Small Animal Veterinary Association Global Pain Council (WSAVA-GPC) has recently published its first "capsule review" by Monteiro et al. These are short articles that present a brief assessment of the scientific evidence and practical recommendations on important, and sometimes controversial, subjects in pain management. The capsules will be published regularly in the Journal of Small Animal Practice, the official journal of the WSAVA. This second article discusses the use of intraperitoneal and incisional analgesia in small animal practice, including their limitations and recommendations by the authors.

Long-term use of non-steroidal anti-inflammatory drugs in cats with chronic kidney disease: from controversy to optimism

This is the first of a series of capsule reviews published by the World Small Animal Veterinary Association - Global Pain Council (WSAVA-GPC). Each of these short articles provides a brisk assessment of the scientific evidence in specific aspects of pain management, including analgesic techniques, recommendations and controversies surrounding their use. In this first capsule review, the scientific evidence available on the long-term use of non-steroidal anti-inflammatory drugs in cats with concomitant chronic pain and chronic kidney disease is discussed.

Randomised clinical trial comparing clinically relevant sedation outcome measures in dogs after intramuscular administration of medetomidine in combination with midazolam or butorphanol for routine diagnostic imaging procedures

The aim of this study was to investigate the sedative effects of medetomidine in combination with midazolam or butorphanol for routine imaging procedures in dogs. Eighty client owned dogs were recruited in a prospective, randomised, blinded clinical study and randomly assigned to receive one of four treatments intramuscularly (IM): (1) 30μg/kg medetomidine (Med30); (2) 20μg/kg medetomidine combined with 0.3mg/kg butorphanol (Med20But0.3); (3) 20μg/kg medetomidine combined with 0.3mg/kg midazolam (Med20Mid0.3); and (4) 10μg/kg medetomidine combined with 0.3mg/kg midazolam (Med10Mid0.3). The level of sedation was evaluated using a composite sedation scale assessed by one investigator (0=no sedation, 15=profound sedation). The number of dogs deemed to be adequately clinically sedated and the dose of propofol administered as rescue sedation were recorded. Mean±standard deviation sedation scores at 30min after the commencement of treatment in the groups that received Med20But0.3 (9.8±4) and Med20Mid0.3 (8.9±4.4) were not statistically significantly different from each other, but were significantly different from the group receiving Med10Mid0.3 (5.6±3.6). Only Med20But0.3 was significantly associated with adequate clinical sedation, while Med10Mid0.3 was associated with 85% sedation failure. The rescue sedation dose of propofol (1.5±1mg/kg) for the Med10Mid0.3 group was significantly higher than for other treatments. A sedation score≥10 out of 15 was a satisfactory cut-off to predict adequate clinical sedation. In healthy dogs, the combination of medetomidine with midazolam did not provide comparable sedation to the same dose of medetomidine in combination with butorphanol in a clinical setting.

A comparison between methadone and buprenorphine for perioperative analgesia in dogs undergoing ovariohysterectomy

OBJECTIVE

To investigate whether preoperative methadone provides superior perioperative analgesia compared to buprenorphine in dogs undergoing ovariohysterectomy.

METHODS

Eighty female dogs were recruited to an assessor-blinded, randomised, clinical trial. Dogs received a premedication dose of 0·05 mg/kg acepromazine or 10 μg/kg medetomidine combined with either 0·3 mg/kg methadone or 20 μg/kg buprenorphine intramuscularly. Anaesthesia was induced with propofol and maintained with isoflurane. Pain was assessed using two scoring schemes (a dynamic interactive visual analogue scale and the short form of the Glasgow Composite Pain Scale) before premedication, 30 minutes later and every hour for 8 hours after premedication. If indicated, rescue analgesia was provided with methadone. Meloxicam was administered after the final assessment. The area under the curve for change in pain scores over time and the requirement for rescue analgesia were compared between groups.

RESULTS

Groups premedicated with buprenorphine had significantly higher pain scores than those premedicated with methadone. There was no interaction between opioid and sedative for any outcome measure. Rescue analgesia was required by significantly more dogs premedicated with buprenorphine (45%) than that of methadone (20%).

CLINICAL SIGNIFICANCE

At the doses investigated, methadone produced superior postoperative analgesia compared to buprenorphine in dogs undergoing ovariohysterectomy.

An investigation of mechanical nociceptive thresholds in dogs with hind limb joint pain compared to healthy control dogs

This study investigated the effects of osteoarthritis (OA) on somatosensory processing in dogs using mechanical threshold testing. A pressure algometer was used to measure mechanical thresholds in 27 dogs with presumed hind limb osteoarthritis and 28 healthy dogs. Mechanical thresholds were measured at the stifles, radii and sternum, and were correlated with scores from an owner questionnaire and a clinical checklist, a scoring system that quantified clinical signs of osteoarthritis. The effects of age and bodyweight on mechanical thresholds were also investigated. Multiple regression models indicated that, when bodyweight was taken into account, dogs with presumed osteoarthritis had lower mechanical thresholds at the stifles than control dogs, but not at other sites. Non-parametric correlations showed that clinical checklist scores and questionnaire scores were negatively correlated with mechanical thresholds at the stifles. The results suggest that mechanical threshold testing using a pressure algometer can detect primary, and possibly secondary, hyperalgesia in dogs with presumed osteoarthritis. This suggests that the mechanical threshold testing protocol used in this study might facilitate assessment of somatosensory changes associated with disease progression or response to treatment.

Genome Analysis of Two Pseudonocardia Phylotypes Associated with Acromyrmex Leafcutter Ants Reveals Their Biosynthetic Potential

The attine ants of South and Central America are ancient farmers, having evolved a symbiosis with a fungal food crop >50 million years ago. The most evolutionarily derived attines are the Atta and Acromyrmex leafcutter ants, which harvest fresh leaves to feed their fungus. Acromyrmex and many other attines vertically transmit a mutualistic strain of Pseudonocardia and use antifungal compounds made by these bacteria to protect their fungal partner against co-evolved fungal pathogens of the genus Escovopsis. Pseudonocardia mutualists associated with the attines Apterostigma dentigerum and Trachymyrmex cornetzi make novel cyclic depsipeptide compounds called gerumycins, while a mutualist strain isolated from derived Acromyrmex octospinosus makes an unusual polyene antifungal called nystatin P1. The novelty of these antimicrobials suggests there is merit in exploring secondary metabolites of Pseudonocardia on a genome-wide scale. Here, we report a genomic analysis of the Pseudonocardia phylotypes Ps1 and Ps2 that are consistently associated with Acromyrmex ants collected in Gamboa, Panama. These were previously distinguished solely on the basis of 16S rRNA gene sequencing but genome sequencing of five Ps1 and five Ps2 strains revealed that the phylotypes are distinct species and each encodes between 11 and 15 secondary metabolite biosynthetic gene clusters (BGCs). There are signature BGCs for Ps1 and Ps2 strains and some that are conserved in both. Ps1 strains all contain BGCs encoding nystatin P1-like antifungals, while the Ps2 strains encode novel nystatin-like molecules. Strains show variations in the arrangement of these BGCs that resemble those seen in gerumycin gene clusters. Genome analyses and invasion assays support our hypothesis that vertically transmitted Ps1 and Ps2 strains have antibacterial activity that could help shape the cuticular microbiome. Thus, our work defines the Pseudonocardia species associated with Acromyrmex ants and supports the hypothesis that Pseudonocardia species could provide a valuable source of new antimicrobials.

Comparison of two passive warming devices for prevention of perioperative hypothermia in dogs

OBJECTIVE

To compare effects of two passive warming methods combined with a resistive heating mat on perioperative hypothermia in dogs.

MATERIALS AND METHODS

Fifty-two dogs were enrolled and randomly allocated to receive a reflective blanket (Blizzard Blanket) or a fabric blanket (VetBed). In addition, in the operating room all dogs were placed onto a table with a resistive heating mat covered with a fabric blanket. Rectal temperature measurements were taken at defined points. Statistical analysis was performed comparing all Blizzard Blanket-treated to all VetBed-treated dogs, and VetBed versus Blizzard Blanket dogs within spay and castrate groups, spay versus castrate groups and within groups less than 10 kg or more than 10 kg bodyweight.

RESULTS

Data from 39 dogs were used for analysis. All dogs showed a reduction in perioperative rectal temperature. There were no detected statistical differences between treatments or between the different groups.

CLINICAL SIGNIFICANCE

This study supports previous data on prevalence of hypothermia during surgery. The combination of active and passive warming methods used in this study prevented the development of severe hypothermia, but there were no differences between treatment groups.

A multicentre, prospective, randomised, blinded clinical trial to compare some perioperative effects of buprenorphine or butorphanol premedication before equine elective general anaesthesia and surgery

Reasons for performing study

Buprenorphine, a μ‐agonist opioid, has recently been licensed for equine use, but butorphanol, a κ‐agonist opioid, is more commonly used in horses. The effect of the 2 opioids has not previously been compared in a large clinical study.

Objectives

To compare post operative analgesia and physiological variables in horses undergoing elective surgery following premedication with either buprenorphine or butorphanol in a conventional clinical setting.

Study design

Multicentre, prospective, randomised, blinded clinical investigation.

Methods

Eighty‐nine healthy horses admitted for elective surgery to one of 6 UK equine veterinary clinics were premedicated with acepromazine, a nonsteroidal anti‐inflammatory drug, and romifidine followed by intravenous (i.v.) buprenorphine or butorphanol. Anaesthesia was induced with diazepam/ketamine and maintained with isoflurane in oxygen. A range of surgical procedures were performed and supplementary anaesthetic agents given as required. Physiological variables were monitored during anaesthesia and pain, ataxia, sedation and vital function were assessed post operatively. Data were analysed using t‐tests, ANOVA, Mann–Whitney U‐test and Chi‐squared test as appropriate and P<0.05 was regarded as significant, except for multiple comparisons, when P<0.01 was used.

Results

Surgery was carried out successfully in all cases and no mortality or serious morbidity occurred. Physiological variables remained within normal limits and all horses recovered successfully, most standing within 1 h of ceasing anaesthesia. There were no significant differences between groups in any variable except post operative pain when scores (simple descriptive scale) between 3 and 6 h were significantly lower after buprenorphine than after butorphanol.

Conclusions

Horses experienced less post operative pain after buprenorphine than after butorphanol premedication. Compared with butorphanol, buprenorphine did not cause any different effects on vital function.

Refinement of a thermal threshold probe to prevent burns

Thermal threshold testing is commonly used for pain research. The stimulus may cause burning and merits prevention. Thermal probe modifications hypothesized to reduce burning were evaluated for practicality and effect. Studies were conducted on two humans and eight cats. Unmodified probe 0 was tested on two humans and promising modifications were also evaluated on cats. Probe 1 incorporated rapid cooling after threshold was reached: probe 1a used a Peltier system and probe 1b used water cooling. Probe 2 released skin contact immediately after threshold. Probe 3 (developed in the light of evidence of 'hot spots' in probe 0) incorporated reduced thermal mass and even heating across the skin contact area. Human skin was heated to 48℃ (6℃ above threshold) and the resulting burn was evaluated using area of injury and a simple descriptive scale (SDS). Probe 1a cooled the skin but required further heat dissipation, excessive power, was not 'fail-safe' and was inappropriate for animal mounting. Probe 1b caused less damage than no cooling (27 ± 13 and 38 ± 11 mm(2) respectively, P = 0.0266; median SDS 1.5 and 4 respectively, P = 0.0317) but was cumbersome. Probe 2 was unwieldy and was not evaluated further. Probe 3 produced even heating without blistering in humans. With probe 3 in cats, after opioid treatment, thermal threshold reached cut-out (55℃) on 24 occasions, exceeded 50℃ in a further 32 tests and exceeded 48℃ in the remainder. No skin damage was evident immediately after testing and mild hyperaemia in three cats at 2-3 days resolved rapidly. Probe 3 appeared to be suitable for thermal threshold testing.

Progressive supranuclear palsy in a family with TDP-43 pathology

A member of a family with an autosomal dominant pattern of frontotemporal dementia (FTD) with a TDP-43 pathological substrate in other members and no mutations in FTD-associated genes developed behavioral variant FTD followed by Progressive Supranuclear Palsy. Autopsy revealed a pure tauopathy of PSP pattern.

CONCLUSIONS

The findings raise the possibility of shared pathogenic pathways and a proximal genetic abnormality between PSP and FTLD-43.

Spontaneous electroencephalographic changes in a castration model as an indicator of nociception: a comparison between donkeys and ponies

REASONS FOR PERFORMING STUDY

Donkeys are believed to be less demonstrative of pain than ponies. Research into comparative sensory processing between these species is required to elucidate these behavioural differences.

OBJECTIVES

To compare changes in the electroencephalogram (EEG) recorded during castration between donkeys and ponies.

STUDY DESIGN

Prospective clinical study.

METHODS

Six ponies and 6 donkeys were castrated under halothane anaesthesia after acepromazine premedication and thiopental anaesthetic induction. Markers were inserted into the EEG recording at the time of skin incision (skin) and emasculation (emasc) for both testicles (T1 and T2) during a closed castration. Raw EEG data were analysed and the EEG variables median frequency (F50 ), total power (Ptot ) and spectral edge frequency (F95 ) derived using standard techniques. Baseline values of F50 , Ptot and F95 for each animal were used to calculate the percentage change from baseline at T1skin, T2skin, T1emasc and T2emasc.

RESULTS

Decreased F50 values relative to baseline were observed in 4 ponies and 2 donkeys across all castration time points. In the remaining animals, the F50 value increased compared with baseline. Both donkey and pony groups showed an overall decrease in Ptot values compared with baseline at T1skin, but the magnitude of the decrease was significantly less (P = 0.004) in ponies than in donkeys. Donkeys demonstrated an overall greater increase (P = 0.05) in F95 values at T1skin relative to baseline compared with ponies.

CONCLUSIONS

Electroencephalographic responses to the noxious stimulus of castration were noted in both donkeys and ponies. Donkeys demonstrated a greater change in Ptot in response to castration than ponies; thus, donkeys appear to demonstrate a cerebral cortical response to a noxious stimulus that is similar to or greater than that in ponies, suggesting that their subtle behavioural expression of pain is not due to a difference in cortical processing of noxious sensory stimuli.

Objective validation of central sensitization in the rat UVB and heat rekindling model

Background

The UVB and heat rekindling (UVB/HR) model shows potential as a translatable inflammatory pain model. However, the occurrence of central sensitization in this model, a fundamental mechanism underlying chronic pain, has been debated. Face, construct and predictive validity are key requisites of animal models; electromyogram (EMG) recordings were utilized to objectively demonstrate validity of the rat UVB/HR model.

Methods

The UVB/HR model was induced on the heel of the hind paw under anaesthesia. Mechanical withdrawal thresholds (MWTs) were obtained from biceps femoris EMG responses to a gradually increasing pinch at the mid hind paw region under alfaxalone anaesthesia, 96 h after UVB irradiation. MWT was compared between UVB/HR and SHAM-treated rats (anaesthetic only). Underlying central mechanisms in the model were pharmacologically validated by MWT measurement following intrathecal N-methyl-d-aspartate (NMDA) receptor antagonist, MK-801, or saline.

Results

Secondary hyperalgesia was confirmed by a significantly lower pre-drug MWT {mean [±standard error of the mean (SEM)]} in UVB/HR [56.3 (±2.1) g/mm², n = 15] compared with SHAM-treated rats [69.3 (±2.9) g/mm², n = 8], confirming face validity of the model. Predictive validity was demonstrated by the attenuation of secondary hyperalgesia by MK-801, where mean (±SEM) MWT was significantly higher [77.2 (±5.9) g/mm²n = 7] in comparison with pre-drug [57.8 (±3.5) g/mm²n = 7] and saline [57.0 (±3.2) g/mm²n = 8] at peak drug effect. The occurrence of central sensitization confirmed construct validity of the UVB/HR model.

Conclusions

This study used objective outcome measures of secondary hyperalgesia to validate the rat UVB/HR model as a translational model of inflammatory pain.

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The effect of keel fractures on egg production, feed and water consumption in individual laying hens

The impact of keel bone fractures on egg production, egg weight and feed and water consumption in individual laying hens. A total of 165 Lohmann brown laying hens were obtained from a commercial farm that consisted of 105 with keel fractures and 60 without keel fractures. 2. After a 4-d period of acclimatisation, hens were individually housed and provided with ad libitum food and water for a 24-h period. The number of eggs laid, egg weight, feed and water consumption during this period were recorded. Keel bone strength was also assessed. 3. Hens free from keel fractures laid more eggs (91.7% vs. 84.9%) of significantly heavier weight (61.9 g vs. 60.2 g), ate less feed (139 g vs. 151 g) and drank less water (212 ml vs. 237 ml) than hens with fractures. 4. There was a significant positive association between keel fracture severity and water consumption, and a significant negative association between keel fracture severity and egg weight and keel bone strength. 5. This small-scale study on individual birds shows that keel bone fractures may have an impact on the economics of egg production.

The effect of keel fractures on egg production, feed and water consumption in individual laying hens

The impact of keel bone fractures on egg production, egg weight and feed and water consumption in individual laying hens. A total of 165 Lohmann brown laying hens were obtained from a commercial farm that consisted of 105 with keel fractures and 60 without keel fractures. 2. After a 4-d period of acclimatisation, hens were individually housed and provided with ad libitum food and water for a 24-h period. The number of eggs laid, egg weight, feed and water consumption during this period were recorded. Keel bone strength was also assessed. 3. Hens free from keel fractures laid more eggs (91.7% vs. 84.9%) of significantly heavier weight (61.9 g vs. 60.2 g), ate less feed (139 g vs. 151 g) and drank less water (212 ml vs. 237 ml) than hens with fractures. 4. There was a significant positive association between keel fracture severity and water consumption, and a significant negative association between keel fracture severity and egg weight and keel bone strength. 5. This small-scale study on individual birds shows that keel bone fractures may have an impact on the economics of egg production.

Lame broiler chickens respond to non-steroidal anti-inflammatory drugs with objective changes in gait function: a controlled clinical trial

Leg health of intensively reared broiler chickens is a significant problem, yet little is known regarding the nature of lameness-associated pain. Kinematic changes in gait have been reported in naturally lame broilers following subcutaneous non-steroidal anti-inflammatory drug (NSAID) administration, compared to a placebo group. In the current study, an extensive range of gait parameters were defined using a commercial motion-capturing system to record three-dimensional temporospatial information from walking broilers pre- and post-treatment. Data analysis, performed using multi-level models, revealed gait modifications in broilers receiving NSAID, but not in those receiving saline. The effect of walking velocity was accounted for retrospectively. An increase in velocity following NSAID treatment (carprofen: P<0.001; meloxicam: P=0.044) indicated improved walking ability. For several measures, the polarity of the treatment effect depended upon walking speed. At slow speeds certain parameters become more like those of non-lame broilers, which may have been indicative of improved stability: stride length and duration (both NSAIDs), transverse back displacement (meloxicam), and vertical leg displacement (carprofen). However, these same parameters also revealed that NSAID treatment caused imbalance at faster speeds, which may have signified an excessive dosage. Although doses employed were not conclusively effective, evidence was provided that factors besides body conformation influenced mobility in the test cohort. The study showed that the model would be useful in future studies to increase our understanding of pain associated with specific lameness types in broiler chickens.

Perioperative socialization, care and monitoring of National Institutes of Health miniature swine undergoing ocular surgery and sampling of peripheral blood

Swine are a frequent species of choice for testing new surgical procedures and for transplantation studies. However, information concerning best practice to prepare pigs for surgery and postoperative treatment and monitoring is limited, despite a perception that preoperative socialization is beneficial. Therefore we examined the effect of preoperative visits by project personnel on compliance of 26 National Institutes of Health (NIH) minipigs subject to corneal transplantation. We briefly describe sedation and anaesthesia protocols developed for surgery and multiple postoperative interventions in order to facilitate interpretation of data relating to pig compliance. Preoperative visit variables and measures of preoperative socialization were correlated with postoperative outcome. Principal component analysis (PCA) of postoperative outcome variables identified a factor accounting for 53.5% of the variance that was significantly associated with two factors derived from PCA of preoperative factors (accounting, respectively, for 54.7% and 26.0% of the variance; P = 0.019 for the overall model, P = 0.041 and 0.040 for factors 1 and 2, respectively), such that more time spent with pigs before surgery and higher socialization scores were associated with less postoperative stress and difficulty of eye medication. Moreover, two of the preoperative visit variables, time spent with only one person in the pen and time spent with two or more people in the pen, contributed predominantly to PCA factors 1 and 2, respectively, indicating that they were fulfilling two qualitatively different requirements for socialization. We conclude that NIH minipigs are fully compliant with anaesthetic and postoperative experimental procedures provided they are well-socialized to project personnel before surgery.

Use of radiography to identify keel bone fractures in laying hens and assess healing in live birds

The aim of this study was to use radiography to assess and characterise naturally occurring keel bone fractures in laying hens and monitor live birds over several weeks to examine the healing process. Twenty-four Lohmann brown commercial laying hens with varying degrees of keel bone fracture were used in the study. Birds were radiographed regularly over six weeks and the radiographic features and changing appearance of keel bone fractures were evaluated. The radiographic characteristics of old and new fractures were categorised and indicated that 80 per cent of birds entering the study with new fractures had healed after 35 days and five birds had incurred new fractures irrespective of their original fracture status.

Effects of acepromazine, butorphanol and buprenorphine on thermal and mechanical nociceptive thresholds in horses

REASONS FOR PERFORMING STUDY

To investigate the antinociceptive effects of buprenorphine administered in combination with acepromazine in horses and to establish an effective dose for use in a clinical environment.

OBJECTIVES

To evaluate the responses to thermal and mechanical stimulation following administration of 3 doses of buprenorphine compared to positive (butorphanol) and negative (glucose) controls.

METHODS

Observer blinded, randomised, crossover design using 6 Thoroughbred geldings (3-10 years, 500-560 kg). Thermal and mechanical nociceptive thresholds were measured 3 times at 15 min intervals. Horses then received acepromazine 0.05 mg/kg bwt with one of 5 treatments i.v.: 5% glucose (Glu), butorphanol 100 µg/kg bwt (But) buprenorphine 5 µg/kg bwt (Bup5), buprenorphine 7.5 µg/kg bwt (Bup7.5) and buprenorphine 10 µg/kg bwt (Bup10). Thresholds were measured 15, 30, 45, 60, 90, 120, 150, 180, 230 min, 4, 5, 6, 7, 8, 9, 10, 11, 12 and 24 h post treatment administration. The 95% confidence intervals for threshold temperature (ΔT) for each horse were calculated and an antinociceptive effect defined as ΔT, which was higher than the upper limit of the confidence interval. Duration of thermal antinociception was analysed using a within-subjects ANOVA and peak mechanical thresholds with a general linear model with post hoc Tukey tests. Significance was set at P<0.05.

RESULTS

Mean (± s.d.) durations of thermal antinociception following treatment administration were: Glu 0.5 (1.1), But 2.9 (2.0), Bup5 7.4 (2.3), Bup7.5 7.8 (2.7) and Bup10 9.4 (1.1) h. B5, B7.5 and B10 were significantly different from Glu and But. No serious adverse effects occurred, although determination of mechanical thresholds was confounded by locomotor stimulation.

CONCLUSIONS

Administration of acepromazine and all doses of buprenorphine produced antinociception to a thermal stimulus for significantly longer than acepromazine and either butorphanol or glucose.

POTENTIAL RELEVANCE

This study suggests that buprenorphine has considerable potential as an analgesic in horses and should be examined further under clinical conditions and by investigation of the pharmacokinetic/pharmacodynamic profile.

Assessment of the sedative effects of buprenorphine administered with 10 μg/kg detomidine in horses

The aim of this randomised, observer-blinded, crossover study was to compare the effects of six treatments, administered intravenously to six horses: saline and saline (S/S); detomidine and saline (D/S); detomidine and 5 µg/kg buprenorphine (D/B5); detomidine and 7.5 µg/kg buprenorphine (D/B7.5); detomidine and 10 µg/kg buprenorphine (D/B10); and detomidine and 25 µg/kg butorphanol (D/BUT). The detomidine dose was 10 µg/kg for all treatments in which it was included. Sedation was subjectively assessed and recorded on a visual analogue scale. Peak sedation, duration of sedation and the area under the curve (AUC) for sedation scores were investigated using a univariate general linear model with post-hoc Tukey tests (P<0.05). Peak sedation and duration of sedation were statistically significantly different between treatments (P<0.001). No sedation was apparent after administration of S/S. The AUC was significantly different between treatments (P=0.010), with S/S being significantly different from D/S, D/BUT, D/B5 and D/B7.5, but not D/B10 (P=0.051).

A small, silent, low friction, linear actuator for mechanical nociceptive testing in veterinary research

Air pressure is commonly used to drive a mechanical stimulus for nociceptive threshold testing. This may be bulky, noisy, non-linear and suffer from friction, hence development of a better system is described. A novel, light (14 g) rolling diaphragm actuator was constructed, which supplied 20 N force via a constant actuation area irrespective of the pressure and position in the stroke. Three round-ended pins, 2.5 mm diameter, mounted in a triangle on the piston, provided the stimulus. Pressure was increased manually using a syringe with the rate of rise of force controlled at 0.8 N/s by warning lights. The pressure/force relationship was calibrated using a static force transducer and mercury column. Data were collected with the actuator attached to the anteromedial radius of 12 cats and four dogs. Mechanical threshold was recorded when the animal withdrew the limb and/or turned towards the actuator. Safety cut-off was 20 N. The pressure/force relationship was linear and independent of the start point in the actuator stroke. Baseline feline thresholds were 10.0 ± 2.5 N (mean ± SD), which increased significantly 30 min after butorphanol administration. Baseline canine thresholds were 5.5 ± 1.4 N and increased significantly between 15 and 45 min after administration of fentanyl or butorphanol. The system overcame the problems of earlier devices and detected an opioid-induced increase in threshold. It has considerable advantages over previous systems for research in analgesia.

Electroencephalographic responses to concussive non-penetrative captive-bolt stunning in halothane - anaesthetised calves

AIM

To investigate the electroencephalographic (EEG) and cardiovascular responses of halothane-anaesthetised calves to non-penetrative captive-bolt stunning.

METHODS

Ten calves were minimally anaesthetised with halothane, using an established anaesthesia protocol. The EEG, blood pressure and electrocardiogram (ECG) were recorded before and after non-penetrative captive-bolt stunning. Visual inspection and alterations in the total power of the EEG (Ptot) were used to investigate the effects of stunning.

RESULTS

Captive-bolt stunning significantly altered cerebrocortical function in all animals. In four animals, Ptot decreased immediately following stunning and remained low throughout the recording period. In another five animals, Ptot responded to stunning in a biphasic manner characterised by an immediate decrease followed by a transient increase and then a final decrease to values similar to those of the non-biphasic animals.

CONCLUSIONS

Non-penetrative captive-bolt stunning significantly altered cerebrocortical function in halothane-anaesthetised calves. The changes in cerebrocortical function would be sufficient to produce insensibility within 0 to 14 seconds in conscious animals.

Amelioration of electroencephalographic responses to slaughter by non-penetrative captive-bolt stunning after ventral-neck incision in halothane - anaesthetised calves

AIM

To investigate the ability of non-penetrative captive-bolt stunning delivered after ventral-neck incision to ameliorate responses to noxious stimulation associated with slaughter by ventral-neck incision in halothane-anaesthetised calves.

METHODS

Seven calves were minimally anaesthetised with halothane, using an established anaesthesia protocol. Electroencephalographic (EEG) indices of cerebrocortical activity were measured in response to ventral-neck incision followed 5 seconds later by non-penetrative captive-bolt stunning. Changes in heart rate and arterial blood pressure were measured and instances of occlusion of the carotid arteries were also noted.

RESULTS

After ventral-neck incision there were periods of an active EEG in some calves, which ceased after non-penetrative captive-bolt stunning in most of the animals. Two calves had periods of active EEG following stunning. Arterial blood pressure decreased significantly after neck incision in all calves, including three with occlusion of the carotid arteries.

CONCLUSIONS

Non-penetrative captive-bolt stunning after ventral-neck incision resulted in the cessation of functional cortical activity in the majority of calves. This procedure prevented the development of cerebrocortical responses to ventral-neck incision, demonstrated elsewhere, which would be painful in conscious animals subjected to this procedure. In addition, instances of carotid arterial occlusion had no significant effect on the decrease in arterial blood pressure.

Comparative effects of halothane, isoflurane, sevoflurane and desflurane on the electroencephalogram of the rat

Inhalant anaesthetic agents are commonly used in studies investigating the electroencephalographic (EEG) effects of noxious stimuli in animals. Halothane causes less EEG depression than isoflurane, however, the EEG effects of halothane, isoflurane, sevoflurane and desflurane have not been compared in the same model. This study aimed to compare the EEG effects of these inhalational agents in the rat. Forty male Sprague-Dawley rats were assigned to four groups and anaesthetized with halothane, isoflurane, sevoflurane or desflurane. EEG was recorded from the left and right somatosensory cortices for 5 min at three different multiples of minimal alveolar concentration (MAC) (1.25, 1.5 and 1.75). Median, 95% spectral edge frequency and total power were derived and a single mean value for each was calculated for the first 60 s of each recording period. When the raw EEG contained burst suppression (BS), the BS ratio (BSR) over 60 s was calculated. No BS was found in EEG recorded from the halothane group at any concentration. BS was present at all concentrations with the other anaesthetic agents. BS was almost complete at all concentrations of isoflurane, whereas BSR increased significantly with increasing concentrations of sevoflurane and desflurane. No significant differences were found between the BSR due to the 1.75 MAC multiple of isoflurane, sevoflurane or desflurane. Halothane causes significantly less depression of cortical activity than the newer inhalant agents at equivalent multiples of MAC. These data support the hypothesis that halothane has a fundamentally different mechanism of action than the other inhalant agents.

Application of a modified form of the Glasgow pain scale in a veterinary teaching centre in the Netherlands

The Glasgow Composite Measure Pain Scale was developed to measure acute pain in dogs in a hospital setting. In this investigation a modified version of the scale was applied in a centre with a different surgical case load and analgesic protocols, and where English is not the first language, to test its validity in a different clinical environment. The modified scale was used to score pain in 60 dogs during the 24 hours after surgery. Their levels of sedation and a clinical impression of their pain were scored at the same time. Three questions were considered; first, how the modified pain score was related to the pain assessed subjectively, secondly, how it related to variables such as the surgical procedure and the dog's health and thirdly, how it changed over time. The mean modified pain scores for the dogs rated subjectively as having no, mild, moderate or severe pain were significantly different, indicating that the modified scale distinguished between pain of different severities. The changes in the dogs' scores also followed the expected changes in their level of pain with time, providing empirical evidence that the scale measures pain.

A comparison of cardiovascular disease risk factor biomarkers in African Americans and Yoruba Nigerians

OBJECTIVE

Classical risk factors for coronary artery disease are changing in the developing world while rates of cardiovascular disease are increasing in these populations. Newer risk factors have been identified for cardiovascular disease, but these have been rarely examined in elderly populations and not those of developing countries.

METHODS

This study was a cross-sectional comparison from a longitudinal, observational, epidemiologic study in which participants are interviewed at three-year intervals. The sample included 1510 African Americans from Indianapolis, Indiana, and 1254 Yoruba from Ibadan, Nigeria. We compared anthropomorphic measurements; biomarkers of endothelial dysfunction (plasminogen activator inhibitor type 1 [PAI-1 and E-selectin), inflammation (C-reactive protein), and lipid oxidation (8-isoprostane); and levels of lipids, homocysteine, folate, and vitamin B12.

RESULTS

Cholesterol, triglycerides, and low-density lipoprotein cholesterol levels were higher in African Americans. For markers of endothelial dysfunction, E-selectin and homocysteine differed between men, and PAI-1 was higher in the Yoruba. C-reactive protein differed only in women, but 8-isoprostane was higher in the Yoruba.

CONCLUSION

Higher lipid levels in African Americans are consistent with their Western diet and lifestyle. Oxidative stress appears to be higher in the Yoruba than in African Americans, which may be secondary to dietary differences. Whether these differences in classical and emerging risk factors account for the different rates of cardiovascular disease, dementia, or other morbidities in these two populations remains to be determined.

Association of statin use with cognitive decline in elderly African Americans

BACKGROUND

Previously reported associations between statin use and incident dementia or cognitive decline have been inconsistent. We report the results from a 3-year prospective study on the association of statin use on cognitive decline and incident dementia in elderly African Americans.

METHODS

A community-based cohort of 1,146 African Americans aged 70 and older living in Indianapolis, Indiana, was evaluated in 2001 and 2004. The instrument used for cognitive assessment was the Community Screening Interview for Dementia (CSI-D). Cognitive decline was defined as CSI-D scores measured at 2001 minus scores at 2004. Measurements of low-density lipoprotein cholesterol (LDL-C) and C-reactive protein (CRP) were obtained from baseline blood samples.

RESULTS

Adjusting for age at baseline, gender, education, and the possession of ApoE epsilon 4 allele, baseline statin use was associated with less cognitive decline (p = 0.0177). There were no significant interactions of statin use when LDL-C and CRP were included. Logistic regression with the four independent variables showed that statin use may be associated with a reduction in incident dementia (OR = 0.32; p = 0.0673). Association with cognitive decline was less clear when investigating statin use over time. Significance remained only for those who discontinued prior to follow-up compared to continuous users or users who started after baseline.

CONCLUSIONS

The relationship between statin use and cognitive decline is complex and subjected to unknown confounders. This effect may not be associated with the cholesterol lowering or anti-inflammatory action of statins.