Animal welfare requirements in publishing guidelines

Descriptions of measures taken to optimize animal welfare are often absent from scientific reports of animal experiments. One reason may be that journal guidelines inadequately compel authors to provide such information. In this study, online English language versions of the 'Guidelines to authors' (GTAs) from 54 national biomedical journals were examined for neutral (unrelated to welfare) and non-neutral keywords referring to: animal welfare; the '3Rs'; the ARRIVE (2010) guidelines, and regulations pertaining to animal experimentation. Journals were selected from nine countries (UK, US, China, Canada, India, Brazil, Germany, Japan and Australia) and seven biomedical specialties (oncology, rheumatology, surgery, pharmacology, medicine, anaesthesia and veterinary medicine). Total GTA word counts varied from 1137 to 31,609. The keyword count identified per category were expressed per myriad (10,000) of total word count. One-way analyses of variance followed by post hoc Tukey pairwise comparisons revealed greater non-neutral per myriad word counts for (a) veterinary GTAs compared with medicine, oncology, rheumatology or surgery; (b) British, compared with Australian, Canadian, German and Japanese GTAs; and (c) no differences between non-neutral categories. The English language versions of GTAs of British and veterinary medical journals contain more words associated with animal welfare, the 3Rs and the ARRIVE guidelines than those from eight other countries and six other medical specialities. The exclusion of 'national' language versions from analysis precludes attempts to identify national differences in attitudes to laboratory animal welfare.

Noninvasive Detection of Ischemic Vascular Damage in a Pig Model of Liver Donation After Circulatory Death

BACKGROUND AND AIMS

Liver graft quality is evaluated by visual inspection prior to transplantation, a process highly dependent on the surgeon's experience. We present an objective, noninvasive, quantitative way of assessing liver quality in real time using Raman spectroscopy, a laser-based tool for analyzing biomolecular composition.

APPROACH AND RESULTS

A porcine model of donation after circulatory death (DCD) with normothermic regional perfusion (NRP) allowed assessment of liver quality premortem, during warm ischemia (WI) and post-NRP. Ten percent of circulating blood volume was removed in half of experiments to simulate blood recovery for DCD heart removal. Left median lobe biopsies were obtained before circulatory arrest, after 45 minutes of WI, and after 2 hours of NRP and analyzed using spontaneous Raman spectroscopy, stimulated Raman spectroscopy (SRS), and staining. Measurements were also taken in situ from the porcine liver using a handheld Raman spectrometer at these time points from left median and right lateral lobes. Raman microspectroscopy detected congestion during WI by measurement of the intrinsic Raman signal of hemoglobin in red blood cells (RBCs), eliminating the need for exogenous labels. Critically, this microvascular damage was not observed during WI when 10% of circulating blood was removed before cardiac arrest. Two hours of NRP effectively cleared RBCs from congested livers. Intact RBCs were visualized rapidly at high resolution using SRS. Optical properties of ischemic livers were significantly different from preischemic and post-NRP livers as measured using a handheld Raman spectrometer.

CONCLUSIONS

Raman spectroscopy is an effective tool for detecting microvascular damage which could assist the decision to use marginal livers for transplantation. Reducing the volume of circulating blood before circulatory arrest in DCD may help reduce microvascular damage.

An Anglocentric History of Anaesthetics and Analgesics in the Refinement of Animal Experiments

Previous histories of animal experimentation, e.g., Franco (2013) have focused on ethics, the law and the personalities involved, but not on the involvement of anaesthetics or analgesics. Given that these were major subjects of (UK) Parliamentary debates on vivisection in the mid-19th century and viewed as "indisputable refinements in animal experimentation" (Russell and Burch 1959), it seemed that an analysis of their role was overdue. This commentary has, in interweaving the history of animal experimentation in the UK with the evolution of anaesthesia, attempted to: (1) clarify the evidence for Russell and Burch's view; and (2) evaluate anaesthesia's ongoing contribution to experimental refinement. The history that emerges reveals that the withholding or misuse of anaesthetics and, or analgesics from laboratory animals in the UK has had a profound effect on scientists and indirectly on the attitudes of the British public in general, becoming a major driver for the establishment of the anti-vivisection movement and subsequently, the Cruelty to Animals Act (1876)-the world's first legislation for the regulation of animal experimentation. In 1902, the mismanaged anaesthetic of a dog in the Department of Physiology, University College London resulted in numerous events of public disorder initiated by medical students against the police and a political coalition of anti-vivisectionists, trade unionists, socialists, Marxists, liberals and suffragettes. The importance of anaesthesia in animal experiments was sustained over the following 150 years as small mammalian species gradually replaced dogs and cats as the principle subjects for vivisection. In discussing experimental refinement in their 1959 report, "The Principles of Humane Experimental Technique" Russell and Burch described anaesthetics as "… the greatest single advance in humane technique, (which) has at the same time been virtually indispensable for the advance of experimental biology". Since then, the role of anaesthetics and in particular analgesics has become an unavoidable consideration whenever animal experiments are planned and conducted. This has been accompanied by a proliferation of training and educational programmes in laboratory animal anaesthesia.

Feeding management before gastrointestinal studies in pigs

Pigs are used to model humans in gastrointestinal (GI) studies because of their comparable size, physiology and behaviour: both are monogastric omnivores. A porcine surgical model for testing novel, tethered ultrasound capsule endoscopes (USCE) requires a clean, motile small intestine. Recommendations for human GI tract preparation before the mechanically similar process of video capsule endoscopy describe using oral purgatives, while high-carbohydrate drinks are recommended before colorectal surgery. Reports of the GI preparation of pigs exist but lack technical details, that is, administration, efficacy and side effects. This report details feeding a high-energy liquid diet to 11 female pigs undergoing surgery and USCE which was readily accepted and easily administered, and which produced a clean, motile small intestine and caused no detectable physiological/behavioural abnormalities.

Efficacy of an organophosphorus hydrolase enzyme (OpdA) in human serum and minipig models of organophosphorus insecticide poisoning

Objectives: Current therapeutic options for organophosphorus (OP) insecticide self-poisoning including atropine and oximes are inadequate and case fatality may exceed 20%. An OP hydrolase enzyme, OpdA, has been used for environmental cleansing of OP insecticides and prevented death in rat and non-human primate models of OP insecticide poisoning if given very quickly after exposure. We here tested OpdA's ability to break down OP insecticides in human serum and in clinically relevant minipig models of OP insecticide poisoning.Methods: Human serum was spiked with seven diverse WHO Class II OP insecticides (chlorpyrifos, quinalphos, diazinon, dimethoate, fenthion, phenthoate, and profenofos) and the effect of OpdA on degradation measured. The pharmacodynamic and clinical effects of OpdA treatment were studied in Gottingen minipigs orally poisoned with agricultural formulations of dimethoate EC40 or methyl parathion EC60; pharmacodynamic effects were also assessed in profenofos EC50-poisoned pigs.Results: OpdA effectively hydrolysed OP insecticides in human serum, with rates varying from 856 (SD 44) down to 0.107 (SD 0.01) moles of substrate hydrolysed/mole of enzyme/sec (k_cat) for quinalphos and phenthoate, respectively, although at rates 2-3 log orders less than found in vitro in buffered solution. It showed clinical benefit in minipig models, reducing the dose of noradrenaline required to sustain an adequate mean arterial pressure after dimethoate (mean 0.149 [SD 0.10] μg/kg/h vs. 1.07 [SD 0.77] μg/kg/h, p < .0001) and methyl parathion (mean 0.077 [SD 0.08] μg/kg/h vs. 0.707 [SD 0.49] μg/kg/h, p < .0001) poisoning. OpdA reduced blood OP insecticide concentration and acetylcholinesterase inhibition after poisoning by dimethoate, methyl parathion, and profenofos insecticides.Conclusions: In vitro incubation of OpdA in human serum showed hydrolysis of diverse OP insecticides, although at lower rates than found in buffer solutions. This activity results in clinical and pharmacodynamic efficacy in vivo against several OP insecticides. These results support the testing of OpdA in further animal models before considering human trials to determine whether it may become an urgently required novel therapeutic agent for OP insecticide self-poisoning.

Modest and variable efficacy of pre-exposure hydroxocobalamin and dicobalt edetate in a porcine model of acute cyanide salt poisoning

Background: Dicobalt edetate and hydroxocobalamin are widely used to treat hydrogen cyanide poisoning. However, comparative and quantitative efficacy data are lacking. Although post-exposure treatment is typical, it may be possible to administer these antidotes before exposure to first attenders entering a known site of cyanide release, as supplementary protection to their personal protective equipment.Methods: We established an anaesthetised Gottingen minipig model of lethal bolus potassium cyanide (KCN) injection to simulate high dose hydrogen cyanide inhalation. Doses were similar to human lethal doses of KCN. Dicobalt edetate and hydroxocobalamin were administered shortly before KCN and their effect on metabolic and cardiovascular variables and survival time were measured.Results: Increases in arterial lactate were similar after 0.08 and 0.12 mmol/kg KCN. KCN 0.08 mmol/kg was survived by 4/4 animals with moderate cardiovascular effects, while the 0.12 mmol/kg dose was lethal in 4/4 animals, with a mean time to euthanasia of 28.3 (SEM: 13.9) min. Administration of dicobalt edetate (0.021 mmol/kg, 8.6 mg/kg) or hydroxocobalamin (0.054 mmol/kg, 75 mg/kg) at clinically licenced doses had modest effect on lactate concentrations but increased survival after administration of KCN 0.12 mmol/kg (survival: dicobalt edetate 4/4, hydroxocobalamin 2/4) but not 0.15 mmol/kg (0/4 and 0/4, respectively). In a subsequent larger study, doubling the dose of hydroxocobalamin (0.108 mmol/kg, 150 mg/kg) was associated with a modest but inconsistent increased survival after 0.15 mmol/kg KCN (survival: control 0/8, 75 mg/kg 1/10, 150 mg/kg 3/10) likely due to variable pharmacokinetics.Conclusions: In this porcine study of cyanide exposure, with pre-exposure antidote administration, licenced doses of dicobalt edetate and hydroxocobalamin were effective at just lethal doses but ineffective at less than twice the estimated LD₅₀. The efficacy of a rapidly-administered double-dose of hydroxocobalamin was limited by variable pharmacokinetics. In clinical poisoning scenarios, with delayed administration, the antidotes are likely to be even less effective. New antidotes are required for treatment of cyanide exposures appreciably above the minimum lethal dose.

A Novel Translational Ovine Pulmonary Adenocarcinoma Model for Human Lung Cancer

In vitro cell line and in vivo murine models have historically dominated pre-clinical cancer research. These models can be expensive and time consuming and lead to only a small percentage of anti-cancer drugs gaining a license for human use. Large animal models that reflect human disease have high translational value; these can be used to overcome current pre-clinical research limitations through the integration of drug development techniques with surgical procedures and anesthetic protocols, along with emerging fields such as implantable medical devices. Ovine pulmonary adenocarcinoma (OPA) is a naturally-occurring lung cancer that is caused by the jaagsiekte sheep retrovirus. The disease has similar histological classification and oncogenic pathway activation to that of human lung adenocarcinomas making it a valuable model for studying human lung cancer. Developing OPA models to include techniques used in the treatment of human lung cancer would enhance its translational potential, making it an excellent research tool in assessing cancer therapeutics. In this study we developed a novel OPA model to validate the ability of miniaturized implantable O₂ and pH sensors to monitor the tumor microenvironment. Naturally-occurring pre-clinical OPA cases were obtained through an on-farm ultrasound screening programme. Sensors were implanted into OPA tumors of anesthetized sheep using a CT-guided trans-thoracic percutaneous implantation procedure. This study reports the findings from 9 sheep that received sensor implantations. Time taken from initial CT scans to the placement of a single sensor into an OPA tumor was 45 ± 5 min, with all implantations resulting in the successful delivery of sensors into tumors. Immediate post-implantation mild pneumothoraces occurred in 4 sheep, which was successfully managed in all cases. This is, to the best of our knowledge, the first description of the use of naturally-occurring OPA cases as a pre-clinical surgical model. Through the integration of techniques used in the treatment of human lung cancer patients, including ultrasound, general anesthesia, CT and surgery into the OPA model, we have demonstrated its translational potential. Although our research was tailored specifically for the implantation of sensors into lung tumors, we believe the model could also be developed for other pre-clinical applications.

Transcranial bioimpedance measurement in horses: a pilot study

OBJECTIVE

This pilot study aimed to evaluate the feasibility of transcranial bioimpedance (TCBI) measurement and variability of TCBI values in healthy conscious horses and to study effects of body position and time on TCBI in anaesthetized horses.

STUDY DESIGN

Prospective, observational study.

ANIMALS

A total of four research horses and 16 client-owned horses presented for surgery.

METHODS

After establishing optimal electrode position using computed tomography scans of cadaver heads, TCBI [described using impedance at zero frequency, R_0, (Ω)] was measured in four conscious, resting horses to investigate the feasibility and changes in TCBI over time (80 minutes). Data were compared using a paired t test. TCBI was then measured throughout anaesthesia (duration 92 ± 28 minutes) in 16 horses in dorsal and lateral recumbency. Data were analysed using a general linear model; gamma regression was chosen as a model of characteristic impedance [Z_c; (Ω)] against time. Data are presented as mean ± standard deviation.

RESULTS

No change in R₀ was seen in conscious horses (age = 15.3 ± 7.3 years, body mass = 512 ± 38 kg) over 80 minutes. The technique was well tolerated and caused no apparent adverse effects. In 16 horses (age = 7.4 ± 4.7 years; body mass = 479 ± 134 kg) anaesthetized for 92 ± 28 minutes, Z_c fell during anaesthesia, decreasing more in horses in lateral recumbency than in horses in dorsal recumbency (p = 0.008). There was no relationship between Z_c and body mass or age.

CONCLUSIONS AND CLINICAL RELEVANCE

TCBI is readily measured in horses. TCBI did not change with time in conscious horses, but decreased with time in anaesthetized horses; this change was greater in horses in lateral recumbency, indicating that TCBI changes in anaesthetized horses may be related to the effects of recumbency, general anaesthesia, surgery or a combination of these factors.

Comparison of Brody's formula with respiratory gas analysis for estimating oxygen consumption in anaesthetized dogs

OBJECTIVE

To determine agreement in oxygen consumption (V˙O₂) values calculated using Sykes' formula V˙O₂ = (FiO₂ - Fe'O₂) * V˙_E (where Fi and Fe are the inspired and end-tidal fractional concentrations of O₂, respectively, and V˙_E is minute volume) with values derived using Brody's formula (V˙O₂ = 10 kg^3/4). It was hypothesized that the two methods would not yield statistically significant differences in calculated values.

STUDY DESIGN

Prospective, clinical, pilot study.

ANIMALS

A total of 22 client-owned dogs.

METHODS

Dogs undergoing surgery were anaesthetized with either isoflurane or sevoflurane. The V˙_E, FiO₂ and Fe'O₂ were measured during mechanical ventilation of the lungs (tidal volume 10 mL kg^-1; respiratory rate: 8-12 breaths minute^-1). Oesophageal temperature was maintained between 37.0 °C and 38.5 °C. Values for V˙O₂ derived by Sykes' and Brody's methods were compared and agreement was determined using Bland-Altman analysis.

RESULTS

Mean V˙O₂ values were 4.67 ± 0.51 mL kg^-1 minute^-1 and 5.32 ± 1.69 mL kg^-1 minute^-1 calculated using Brody's formula and Sykes' equation, respectively. There was greater variability in the values obtained from Sykes' equation. The Bland-Altman plot revealed a proportional error with correlation but poor agreement between values.

CONCLUSIONS AND CLINICAL RELEVANCE

Both methods yielded V˙O₂ values of approximately 5 mL kg^-1minute^-1 with no statistically significant differences between the two methods.

A comparison of two ketamine doses for field anaesthesia in horses undergoing castration

BACKGROUND

Ketamine at 2.2 mg/kg given i.v. is often used to induce anaesthesia for surgical procedures in horses under field conditions. Commonly, additional doses are needed to complete the surgery. We hypothesised that surgical conditions would be improved when 5 mg/kg of ketamine was used to induce anaesthesia, while induction and recovery qualities would not differ from those when 2.2 mg/kg ketamine was used.

OBJECTIVE

To compare the anaesthetic effects of two ketamine doses (5 and 2.2 mg/kg) during field anaesthesia for castration of horses.

STUDY DESIGN

Prospective, randomised, blinded, clinical study.

METHOD

Seventy-seven client-owned Icelandic horses presented for castration under field conditions were studied. Pre-anaesthetic medication was xylazine (0.7 mg/kg) butorphanol (25 μg/kg) and acepromazine (50 μg/kg) injected i.v. Anaesthesia was induced with either 2.2 mg/kg (K2.2) or 5 mg/kg (K5) i.v. of ketamine mixed with diazepam (30 μg/kg). The quality of induction, surgical conditions and recovery were compared using subjective and objective measures, and the number of additional ketamine doses recorded.

RESULTS

Ketamine 5 mg/kg provided better surgical conditions and a more rapid induction. Recovery quality was subjectively better in K2.2. Five horses in K2.2 and two in K5 required additional ketamine doses.

MAIN LIMITATIONS

While the pre-anaesthetic sedation and benzodiazepine doses were consistent among horses, the level of sedation and muscle relaxation achieved differed.

CONCLUSION

A ketamine dose of 5 mg/kg can be used to improve the quality of field anaesthesia for castration in Icelandic horses. Although recovery quality is subjectively better when using 2.2 mg/kg, no adverse events were observed during recovery with either dose The Summary is available in Portuguese - see Supporting Information.

A review of factors affecting analgesic selection in large animals undergoing translational research

The widespread physiological effects of pain in experimental animals are likely to reduce the validity of data except when pain itself is studied. Appropriately prescribed analgesics will limit pain and improve the welfare of animals undergoing noxious experimental procedures. However, their injudicious use may also introduce variability in data and limit study reproducibility. Optimizing both animal welfare and the value of scientific data from experimental studies requires the ability to identify, quantify and treat animal pain by applying a knowledge of analgesic pharmacology that is sympathetic to study objectives. This review first examines the reasons for promoting analgesic use in translational animal research and, in focussing on pigs and small ruminants, then identifies factors that should be considered when devising analgesic plans.

PREPARE: guidelines for planning animal research and testing

There is widespread concern about the quality, reproducibility and translatability of studies involving research animals. Although there are a number of reporting guidelines available, there is very little overarching guidance on how to plan animal experiments, despite the fact that this is the logical place to start ensuring quality. In this paper we present the PREPARE guidelines: Planning Research and Experimental Procedures on Animals: Recommendations for Excellence. PREPARE covers the three broad areas which determine the quality of the preparation for animal studies: formulation, dialogue between scientists and the animal facility, and quality control of the various components in the study. Some topics overlap and the PREPARE checklist should be adapted to suit specific needs, for example in field research. Advice on use of the checklist is available on the Norecopa website, with links to guidelines for animal research and testing, at https://norecopa.no/PREPARE .

Anti-colchicine Fab fragments prevent lethal colchicine toxicity in a porcine model: a pharmacokinetic and clinical study

Background: Colchicine poisoning is commonly lethal. Colchicine-specific Fab fragments increase rat urinary colchicine clearance and have been associated with a good outcome in one patient. We aimed to develop a porcine model of colchicine toxicity to study the pharmacokinetics and efficacy of ovine Fab.

Methods: A Göttingen minipig critical care model was established and serial blood samples taken for colchicine and Fab pharmacokinetics, clinical chemistry, and haematology. Animals were euthanised when the mean arterial pressure fell below 45 mmHg without response to vasopressor, or at study completion.

Results: Initial studies indicated that oral dosing produced variable pharmacokinetics and time-to-euthanasia. By contrast, intravenous infusion of 0.25 mg/kg colchicine over 1 h produced reproducible pharmacokinetics (AUC_0–20 343 [SD = 21] µg/L/h), acute multi-organ injury, and cardiotoxicity requiring euthanasia a mean of 22.5 (SD = 3.2) h after dosing. A full-neutralising equimolar Fab dose given 6 h after the infusion (50% first hour, 50% next 6 h [to reduce renal-loss of unbound Fab]) produced a 7.35-fold increase in plasma colchicine (AUC_0–20 2,522 [SD = 14] µg/L/h), and removed all free plasma colchicine, but did not prevent toxicity (euthanasia at 29.1 [SD = 3.4] h). Earlier administration over 1 h of the full-neutralising dose, 1 or 3 h after the colchicine, produced a 12.9-fold (AUC_0–20 4,433 [SD = 607] µg/L/h) and 6.0-fold (AUC_0–20 2,047 [SD = 51] µg/L/h) increase in plasma colchicine, respectively, absence of free plasma colchicine until 20 h, and survival to study end without marked cardiotoxicity.

Conclusions: Colchicine-specific Fab given early, in equimolar dose, bound colchicine, eliciting its movement into the blood, and preventing severe toxicity. Clinical studies are now needed to determine how soon this antidote must be given to work in human poisoning.

LC-MS/MS quantification of free and Fab-bound colchicine in plasma, urine and organs following colchicine administration and colchicine-specific Fab fragments treatment in Göttingen minipigs

Clinical evaluation of a colchicine specific antigen-binding fragment (Fab) in order to treat colchicine poisoning required the development of an accurate method allowing quantification of free and Fab-bound colchicine in plasma and urine, and free colchicine in tissues, to measure colchicine redistribution after Fab administration. Three methods have been developed for this purpose, and validated in plasma, urine and liver: total colchicine was determined after denaturation of Fab by dilution in water and heating; free colchicine was separated from Fab-bound colchicine by filtration with 30KDa micro-filters; tissues were homogenized in a tissue mixer. Deuterated colchicine was used as internal standard. Samples were extracted by liquid-liquid extraction and analyzed with a LC-MS/MS. LOQ were 0.5ng/mL in plasma and urine for free and total colchicine and 5pg/mg in tissues. The methods were linear in the 0.5-100ng/mL range in plasma and urine, and 5-300pg/mg in tissues with determination coefficients>0.99. Precision and accuracy of QC samples presented a CV<9.4%. The methods require only 200μL of sample and allow a high throughput due to short analytical run (2min). These methods were successfully applied to a pig intoxicated with colchicine and treated with colchicine specific Fab fragments.

A Review of Pain Assessment in Pigs

There is a moral obligation to minimize pain in pigs used for human benefit. In livestock production, pigs experience pain caused by management procedures, e.g., castration and tail docking, injuries from fighting or poor housing conditions, “management diseases” like mastitis or streptococcal meningitis, and at parturition. Pigs used in biomedical research undergo procedures that are regarded as painful in humans, but do not receive similar levels of analgesia, and pet pigs also experience potentially painful conditions. In all contexts, accurate pain assessment is a prerequisite in (a) the estimation of the welfare consequences of noxious interventions and (b) the development of more effective pain mitigation strategies. This narrative review identifies the sources of pain in pigs, discusses the various assessment measures currently available, and proposes directions for future investigation.

Are neuromuscular blocking agents being misused in laboratory pigs?

The literature (2012-4) describing experimental pig surgery was reviewed to estimate the extent to which neuromuscular block (NMB) is used, to examine methods for ensuring unconsciousness, and to identify the rationale for use of NMB and establish the anaesthetist's training. In the first stage of a two-stage review, NMB use was estimated using Web of Knowledge to identify articles describing NMB during pig surgeries. In the second stage, PubMed and Google Scholar were used to increase the number of articles for determining measures taken to prevent accidental awareness during general anaesthesia (AAGA). The corresponding authors of screened articles were emailed four times to establish the reason for using NMB and the anaesthetists' backgrounds (medical, veterinary, or technical). The first search revealed NMB use in 80 of 411 (20%) studies. Of the 153 articles analysed in the second stage, two described strategies to reduce AAGA. Some (6%) papers did not provide information on anaesthetic doses; citations supporting anaesthetic efficacy were found in only 13. Five of 69 papers using inhalation agents measured end-tidal anaesthetic concentrations based on human, not porcine, minimal alveolar concentrations. The methods in 13% of articles reporting anaesthetic depth assessment were incomplete or questionable, or both; four described using somatic motor reflexes. Corresponding authors of 121 articles reported that the principal reason for NMB was improved 'surgical visualization' (26%). Medical or veterinary anaesthetists supervised anaesthesia in 70% of studies; non-anaesthetists provided NMB, unsupervised, in 23. Nine respondents prioritized experimental expediency over pig welfare. In laboratory pig studies, AAGA may be prevalent; reported details of its attempted prevention are woefully inadequate.

Review of Practices Reported for Preoperative Food and Water Restriction of Laboratory Pigs (Sus scrofa)

The traditionally cited recommendations for the preoperative restriction of food (including bedding) and water in pigs do not appear to be evidence-based. As a preliminary step in elucidating a rationale for and standardizing preoperative food and water restriction (PFWR), this structured review recorded recent reported practices in PFWR in laboratory pigs and its consequences. Medline, Google Scholar and Web of Science databases were searched for recently published (2012 - 2014) recovery surgery procedures in pigs. Information pertaining to PFWR practices, as delineated in the ARRIVE guidelines, was extracted from the 233 articles retrieved. Food withdrawal was described in 73 of the 233 (31%) papers evaluated, bedding withdrawal in 5 articles (2%), and water withholding in 13 publications (6%) papers. Food, bedding, and water withdrawal regimens had a median (range) duration of 12 (4 to 48), 48 (48 to 72), and 12 (2 to 12) h, respectively. Compared with other types of procedures, articles describing gastrointestinal or abdominal surgery were more likely to report fasting regimes. Liquid diets were described in 11 of the 233 (5%) publications evaluated. Adverse effects of PFWR effects were not reported. These data reveal considerable variation in PFWR practices. The stress of fasting coupled with the absence of evidence for current recommendations makes the rationale and standards for PFWR in pigs worthy of further study.

Prophylactic use of antimicrobials in surgical pig models; a literature review (2012-2014)

There are no guidelines for antimicrobial use in experimental animals even though appropriate selection is required to reduce risk of surgical site infection (SSI) and resistance development. Pigs are used extensively as experimental surgical models for people. This review compares reported antimicrobial prescription in recently published pig surgical studies (retrieved by PubMed, Web of Knowledge and Google Scholar) with human guidelines for prophylactic antimicrobial use (National Institute of Clinical Excellence and the American Society of Health-System Pharmacists). A five-point appropriate antimicrobial use index (AAUI), based on aforementioned guidelines, was used to grade 233 studies. Use of World Health Organization-designated critically important antimicrobials (CIA) was recorded. Antimicrobial use was described in 111 of 233 (48 per cent) papers. AAUI scores of 5 (maximal compliance) and 0 (no compliance) were awarded to 34 (15 per cent) and 101 (43 per cent) articles. Where reported, prophylactic antimicrobials were mostly administered after surgery (62/95, 65 per cent) and intramuscularly (36/72, 50 per cent). CIAs were described in 21 of 111 (19 per cent) papers and SSIs in 21 of 233 (9 per cent). Reported antimicrobial prophylaxis in experimental pig surgery deviates from human clinical guidelines. This has implications for antimicrobial resistance, study quality and animal welfare. Until species-specific guidelines are formulated, experimental surgical studies involving animals would probably benefit from adherence to human guidelines.

Pain management in pigs undergoing experimental surgery; a literature review (2012-4)

Failure to provide effective analgesia to animals in noxious studies contravenes the obligation to refine animal experimentation and, by increasing 'noise' in physiological data sets, may decrease the scientific validity of results. Pig models of surgical conditions are becoming increasingly important and used for translational work. This review aimed to determine the extent to which the recent biomedical literature describes pain assessment and alleviation in pigs recovering from experimental surgery. Three databases (Medline, Web of Knowledge, and Google Scholar) were searched to find relevant studies published from January 2012 to March 2014. Information on pain assessment and peri- and postoperative analgesia was extracted. The review identified 233 papers meeting selection criteria. Most articles (193/233, 83%) described use of drugs with analgesic properties, but only 87/233 (37%) described postoperative analgesia. No article provided justification for the analgesic chosen, despite the lack of guidelines for analgesia in porcine surgical models and the lack of formal studies on this subject. Postoperative pain assessment was reported in only 23/233 (10%) articles. It was found that the reporting of postoperative pain management in the studies was remarkably low, reflecting either under-reporting or under-use. Analgesic description, when given, was frequently too limited to enable reproducibility. Development of a pain-scoring system in pigs, together with the mandatory description of pain management in submitted articles, would contribute to improved laboratory pig welfare.

Influence of age and body mass on the response of adolescent male pigs to anaesthesia

Age and body mass affect a human's response to drugs, including anaesthetics. In pigs, such effects, if they occur, are likely to be pronounced: commercial breeds have been selected for rapid growth, meaning rapid body composition and mass change with age. Thirty-six male pigs were anaesthetised for CT scanning on three occasions (S1-3) when aged 105, 137 and 166 days and when mean (±sd) masses were 57.2±4.4, 88.4±6.2 and 114.7±7.6 kg, respectively. Medetomidine (5 μg/kg), azaperone (1 mg/kg), ketamine (5 mg/kg) and midazolam (0.25 mg/kg) were combined and injected intramuscularly. The times when pigs became recumbent (R1) and remained so (RP) were recorded. If venous cannulation was not possible five minutes after recumbency, 2-3 per cent isoflurane in a 1:2 O2/N2O mixture was delivered by mask until cannulation was possible and then discontinued. If anaesthetic depth was inadequate for CT scanning, a full dose (midazolam 0.25 mg/kg, ketamine 2 mg/kg) or half dose of induction agents was administered intravenously. During recovery from anaesthesia, the times at first movement (M1), first standing attempt (S1) and successful sustained standing (SP) were recorded. The relationship between mass and time (minutes) from injection to each end point was assessed using regression analysis and linear mixed-effect models (LMEM); LMEM were used to assess isoflurane and intravenous anaesthetic effects. Analysis using LMEM showed no significant relationships between mass and the times from injection to the five end points. Isoflurane reduced the time to M1, S1 and SP (P<0.037); intravenous agents had no effect on S1 or SP (P>0.585) but increased the time from injection to M1 (P<0.001). In conclusion, age and mass do not influence the response of commercially bred pigs to the intravenous anaesthetic combination described.

Electrocardiographic indicators of excitability in horses for predicting recovery quality after general anaesthesia

OBJECTIVE

To determine whether preoperative electrocardiographic measurements linked to sympathetic nervous activity could be used to predict recovery quality after general anaesthesia in horses.

STUDY DESIGN

Prospective, clinical study.

ANIMALS

Eighteen adult client-owned horses.

METHODS

The electrocardiogram (ECG) was recorded presurgery in horses under three standard conditions: stabled unattended; with a groom whilst being led along a standard course; alone in the induction box. After surgery, each animal's recovery quality was scored by eight experienced anaesthetists or technicians using Donaldson's scoring system (2000). The digitized ECG recordings were analyzed for T-wave morphology, mean heart rate (HR), HR variability (HRV) and HRV derivatives including mean R-R interval, standard deviation of normal intervals (SDNN) and the root mean square of successive intervals (RMSSD), low (LF) and high frequency (HF) activity and the LF/HF ratio in both fast Fourier transformed and autoregressive spectra. Correlations between ECG variables and recovery score were examined using Spearman's rank correlation.

RESULTS

There was no significant correlation between preanaesthetic ECG measurements and recovery quality.

CONCLUSIONS

Predictions of recovery quality after general anaesthesia in horses cannot be based on preanaesthetic ECG variables.

CLINICAL RELEVANCE

Measures other than those based on the ECG should be investigated as predictors of recovery quality.

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.

A model describing the use of a bronchial blocking device and a sheathed bronchoscope for pulmonary aspiration studies in the Gottingen minipig

The administration of test substances into a single lung, or lung lobe, allows the remaining untreated lung to act as an experimental control and effectively halves the number of animals required in a given experiment. It reduces the likelihood of early fatal pulmonary failure when noxious substances are studied which may lessen the need for replacement animals. However, the ease of substance administration and the subsequent analysis of its effects, for example by bronchoalveolar lavage or bronchoscopy, depend critically on the size of the animal model. The advantages of using minipigs; ease of handling, reduced housing requirements, genetic homogeneity, etc. are reduced if their diminutive size makes lung studies difficult. This article describes the use of a bronchial blocking device and a sheathed bronchoscope which enabled sterile endobronchial substance administration in Göttingen minipigs, and allowed pulmonary aspiration studies to be conducted with each animal acting as its own control.

Translational toxicological research: investigating and preventing acute lung injury in organophosphorus insecticide poisoning

Poisoning through ingestion of organophosphorus (OP) insecticide is a leading cause of suicide globally. Severe poisoning with OP compounds creates an unconscious, paralysed patient with respiratory failure. These symptoms make pulmonary aspiration of stomach contents highly likely, potentially causing an acute lung injury. To explore this hypothesis, we created a Gottingen minipig pulmonary aspiration model (n=26) to investigate the mechanism and severity of lung injury created through pulmonary instillation of 0.5 mL/kg mixtures of porcine gastric juice (GJ), OP and/or its solvent. Early results show that aspiration of OP and GJ causes pulmonary neutrophil sequestration, alveolar haemorrhage and interstitial oedema, with disruption of the alveolar-capillary membrane. Further measurements will include quantitative CT imaging, histopathology scoring, acute lung injury biomarkers and respiratory function. In order to test the validity of the minipig model, a pilot study in Sri Lanka has been devised to observe signs of lung injury in human patients who have ingested OP insecticide with or without clinical evidence of pulmonary aspiration. Lung injury will be assessed with PaO2/FIO2 ratios and physiological dead space measurement. Blood, bronchoalveolar lavage and urine will be taken at 24 and 48 h after poisoning and at 3-4 h in surgical control patients to measure acute lung injury biomarkers. An unpublished toxicology study from Sri Lanka, 2011-2012, showed that over 40% of unconscious poisoned patients with a GCS <9 were not intubated for ambulance transfer between rural and district hospitals. Delay in intubation leads to aspiration pneumonitis and pneumonia in 38%-45% of unconscious poisoned patients. We hypothesise that non-drug assisted placement of supraglottic airways may be a good tool for use in unconscious poisoned patients requiring transfer from small rural hospitals in Asia. They could confer better airway protection than no airway intervention and reduce both morbidity and mortality.

Factors affecting the perception of recovery quality in horses after anaesthesia

REASONS FOR PERFORMING STUDY

A significant effect of gender, experience and background, i.e. an evaluator's relationship with horses as equine anaesthetists, orthopaedic surgeons, practitioners or owners, on perceptions of recovery quality after anaesthesia would reduce the validity of recovery quality scoring systems.

OBJECTIVES

To determine the effects of evaluator background, experience and gender on their perceptions of recovery quality; and questionnaire response rate as a function of background.

STUDY DESIGN

Cross-sectional survey.

METHODS

A total of 440 potential evaluators were invited to evaluate the video-recorded recoveries of 24 horses using a visual analogue scale (VAS) in which 0 = worst, 100 = best possible recovery. A mean score was generated for each of the 1-24 recoveries within each background group. These were compared using Spearman's rank correlation. The effect of gender and experience on VAS scores were analysed using an ordinal logistic regression after scores were categorised into 'intermediate, 'worst' and 'best' recovery categories based on median, 25th and 75th percentile VAS scores, respectively.

RESULTS

The overall response rate was 35%. The greatest was from the anaesthetists (78%) followed by surgeons (43%). The response rate among owners and practitioners was 26%. Correlation among VAS scores across all background groups was high (Spearman rank > 0.90; P < 0.001). Among the combined veterinarians, there was no significant gender (P = 0.551) or experience (P = 0.103) effect. Among horse owners, the effect of experience was not significant (P = 0.116) although gender was (P = 0.027). Male horse owners awarded significantly greater scores than females.

CONCLUSIONS

When VAS are used to grade recovery quality, neither the background nor the gender of veterinary evaluators affects quality perception. Male owners awarded greater scores than female owners, implying that they are less critical of recovery quality and a gender effect among horse owners must be considered when VAS are used to score recovery quality.

The perioperative care of lambs and ewes when the former undergo major experimental (scoliotic) surgery

The purpose of the study was to optimize postoperative comfort in lambs anaesthetized for the surgical creation of scoliosis while maintaining the ewe-lamb relationship to miminize rejection rates. The first management plan produced six scoliotic lambs but intraoperative hypoventilation and hypovolaemia followed by postoperative dyspnoea, pain, monitoring and nursing difficulties, hypothermia, hypoglycaemia and tympany were encountered. Three of eight lambs (38%) were rejected by their ewes. Perioperative management was amended which, combined with improved surgical technique, produced 16 scoliotic lambs. The lambs recovered more rapidly (mean time to standing after discontinuation of anaesthesia was reduced from 12 h to 70 min) and appeared to be more comfortable. No rejections occurred after the refinements were implemented.

A comparison of two morphine doses on the quality of recovery from general anaesthesia in horses

Previous studies indicated that perioperative morphine improves recovery quality after general anaesthesia in horses. This clinical trial investigated whether this effect was dose-dependant. Twenty-six horses anaesthetised for surgery were block-randomised to receive one of two intraoperative morphine treatments: Treatment M1 consisted of a constant rate infusion (CRI) of morphine at 0.1mg/kg/h, begun after a loading dose (LD) of 0.15 mg/kg. Treatment M2 was a CRI of 0.2mg/kg/h preceded by an LD of 0.3mg/kg. During recovery, times at the first attempt and at achieving sternal recumbency and standing, and the total recovery duration were not different between groups. Total recovery quality score was not significantly different between groups. Scores for the "sternal phase" were higher (of poorer quality) for M2 but scores in both groups were low. Morphine doses of M2, which are greater than those described previously, do not appear to alter or improve the quality or duration of recovery in horses after surgical anaesthesia.

Near-fatal misuse of medical tape around an endotracheal tube connector during inhalation anesthesia in a horse

A 7-year-old gelded Irish sports horse weighing 650 kg was anesthetized on 2 consecutive days for lavage of a septic right radio-carpal joint. On both occasions the endotracheal tube connector, which had been bound in medical tape to produce an airtight seal, functioned as a unidirectional valve during mechanical ventilation, retarding expiration, imposing positive end expiratory pressure (PEEP), and probably continuous positive airway pressure (CPAP). The equipment dysfunction was not identified on either occasion despite close inspection prompted by progressive increases in airway pressure and thoracic distension. Whilst the PEEP and CPAP exerted unexpectedly modest cardiovascular effects and the horse recovered uneventfully on both occasions, the improvisation may have proven fatal in a higher-risk subject.

A 7-year-old gelded Irish sports horse weighing 650 kg was anesthetized on 2 consecutive days for lavage of a septic right radio-carpal joint. On both occasions the endotracheal tube connector, which had been bound in medical tape to produce an airtight seal, functioned as a unidirectional valve during mechanical ventilation, retarding expiration, imposing positive end expiratory pressure (PEEP), and probably continuous positive airway pressure (CPAP). The equipment dysfunction was not identified on either occasion despite close inspection prompted by progressive increases in airway pressure and thoracic distension. Whilst the PEEP and CPAP exerted unexpectedly modest cardiovascular effects and the horse recovered uneventfully on both occasions, the improvisation may have proven fatal in a higher-risk subject.

The construction and evaluation of a device for mechanomyography in anaesthetized Göttingen minipigs

OBJECTIVE

To devise a method for assessing evoked muscle strength on nerve stimulation [mechanomyography (MMG)] in the anaesthetized minipig.

STUDY DESIGN

Prospective observational.

ANIMALS

Sixty male Göttingen minipigs weighing 10.5-26.0 kg.

METHODS

After cadaveric studies, a limb fixation device was constructed which allowed the twitch responses of the pelvic limb digital extensor muscles to be measured by force-displacement transduction in response to supramaximal train-of-four (TOF) stimulation of the common peroneal nerve. The device was tested in 60 minipigs weighing 10.5-26.0 kg positioned in dorsal recumbency.

RESULTS

The technique recorded the MMG of the common peroneal-pelvic limb digital extensor nerve-muscle unit for up to 12 hours during which twitch height remained constant in 18 animals in which single twitch duration was <300-500 ms. In 42, in which twitch duration was >300-500 ms, 2 Hz nerve stimulation caused progressive baseline elevation (reverse fade) necessitating a modified signal capture method for TOF ratio (TOFR) computation. However, T1 was unaffected. The mean (range) of the TOFR in pigs with reverse fade was 1.2 (1.1-1.3).

CONCLUSIONS AND CLINICAL RELEVANCE

The technique allowed MMG recording in unparalysed pigs in response to TOF nerve stimulation and revealed a hitherto unreported complication of MMG monitoring using TOF in animals: reverse fade. This complicated TOFR calculation.

A role for solvents in the toxicity of agricultural organophosphorus pesticides

Organophosphorus (OP) insecticide self-poisoning is responsible for about one-quarter of global suicides. Treatment focuses on the fact that OP compounds inhibit acetylcholinesterase (AChE); however, AChE-reactivating drugs do not benefit poisoned humans. We therefore studied the role of solvent coformulants in OP toxicity in a novel minipig model of agricultural OP poisoning. Gottingen minipigs were orally poisoned with clinically relevant doses of agricultural emulsifiable concentrate (EC) dimethoate, dimethoate active ingredient (AI) alone, or solvents. Cardiorespiratory physiology and neuromuscular (NMJ) function, blood AChE activity, and arterial lactate concentration were monitored for 12h to assess poisoning severity. Poisoning with agricultural dimethoate EC40, but not saline, caused respiratory arrest within 30 min, severe distributive shock and NMJ dysfunction, that was similar to human poisoning. Mean arterial lactate rose to 15.6 [SD 2.8] mM in poisoned pigs compared to 1.4 [0.4] in controls. Moderate toxicity resulted from poisoning with dimethoate AI alone, or the major solvent cyclohexanone. Combining dimethoate with cyclohexanone reproduced severe poisoning characteristic of agricultural dimethoate EC poisoning. A formulation without cyclohexanone showed less mammalian toxicity. These results indicate that solvents play a crucial role in dimethoate toxicity. Regulatory assessment of pesticide toxicity should include solvents as well as the AIs which currently dominate the assessment. Reformulation of OP insecticides to ensure that the agricultural product has lower mammalian toxicity could result in fewer deaths after suicidal ingestion and rapidly reduce global suicide rates.

Quantitative and qualitative comparison of three scoring systems for assessing recovery quality after general anaesthesia in horses

OBJECTIVE

To assess the reproducibility and repeatability of two commonly used recovery quality scoring systems and compare them with those of a novel system based on a greater number of objective criteria.

ANIMALS

The video-recorded recoveries of ten client-owned horses selected from all recovery recordings taken between September 2005 and March 2006 at the Royal (Dick) School of Veterinary Studies.

MATERIALS AND METHODS

A digital versatile disc (DVD) was produced using edited video recordings of ten horses recovering from general anaesthesia. Twelve experienced equine anaesthetists (raters) studied the DVD on three occasions, and scored the recovery quality of each horse using one of three scoring systems (P, D or E) on each occasion. The process was repeated 6 months later (t = 6) to measure intra-observer reliability (repeatability). At first use (t = 0) raters were asked to comment on the advantages and disadvantages of each system.

RESULTS

Inter-rater variability was limited for each system: at each observation period raters accounted for 0.3-4.4% variation. System P was insensitive to differences between recoveries. In system D, score variability increased as recovery quality deteriorated. Intra-rater variability varied with system: using system P, raters provided consistent scores between the observation periods for some, but not all horses ('horse' and 'rater' accounted for 9.7% and 1.9% of variation respectively). Raters were less consistent between t = 0 and t = 6 using system D, but each horse was scored with similar consistency. System E produced little variation at the level of horse (1.0%) and rater (1.9%). Raters broadly agreed on the principle advantages and disadvantages of the three systems.

CONCLUSIONS AND CLINICAL RELEVANCE

The systems examined showed reliability and reproducibility but practicality and simplicity of use appeared to be inextricably linked with imprecision. Further work is required to produce a suitable recovery quality scoring system.

Reducing the oxygen concentration of gases delivered from anaesthetic machines unadapted for medical air

High fractional concentrations of inspired oxygen (FiO(2)) delivered over prolonged periods produce characteristic histological changes in the lungs and airway of exposed animals. Modern medical anaesthetic machines are adapted to deliver medical air (FiO(2)=0.21) for the purpose of reducing FiO(2); anaesthetic machines designed for the veterinary market have not been so adapted. Two inexpensive modifications that allow medical air to be added to the gas flow from veterinary anaesthetic machines are described. The advantages and disadvantages of each modification are discussed.

Postoperative complications in a lamb after major surgery

INTRODUCTION

Anaesthesia in lambs undergoing experimental surgery may develop problems associated with age-related immune incompetency: a postoperative complication in a 3 week old Scottish blackface lamb after spinal surgery is presented. CASE HISTORY AND MANAGEMENT: Both lamb and ewe were in good condition. The ewe was vaccinated against Clostridium perfringens and Clostridium tetani 5 weeks pre-partum. There were no apparent problems with the lamb's intake of colostrum. Pre-anaesthetic medication was intramuscular medetomidine (10 μg kg(-1)). Anaesthesia was induced and maintained with sevoflurane in oxygen. Morphine (0.5 mg kg(-1)), meloxicam (0.6 mg kg(-1)) and ketamine (1 mg kg(-1) followed by 10 μg kg(-1) minute(-1)) were administered intravenously (IV) for perioperative analgesia. Atracurium (0.5 mg kg(-1) IV, followed by 0.17 mg kg(-1) injected when the first twitch of the four, train-of four count was palpated) was used to improve muscle relaxation. The lamb's trachea was intubated and the lungs mechanically ventilated to maintain normocapnia. Intrathecal morphine (0.2 mg kg(-1)), IV meloxicam (0.3 mg kg(-1)) and edrophonium (0.5 mg kg(-1)) were administered before recovery. Operative and initial recovery periods were unremarkable. Three hours after surgery the lamb became depressed. Tachycardia (180-250 beats minute(-1)), tachypnoea (30 breaths minute(-1)), poor peripheral perfusion and cold pelvic limb extremities were present mimicking severe pain, and/or hypovolaemic shock. Analgesics - morphine (total dose 1.3 mg kg(-1)) - and IV fluid therapy boluses - crystalloids (300 mL), colloids (120 mL) and fresh whole blood (60 mL) - failed to ameliorate clinical signs and so the lamb was euthanized 10 hours after surgery. Post-mortem findings supported a possible diagnosis of peracute Clostridium perfringens enterotoxaemia.

CONCLUSION

Clostridium perfringens enterotoxaemia should be considered when clinical signs of severe pain and/or hypovolaemic shock fail to respond to analgesics and fluid resuscitation in lambs after major surgery.

A study of the correlation between objective and subjective indices of recovery quality after inhalation anaesthesia in equids

OBJECTIVE

To examine the association between objective and subjective descriptors used for assessing recovery quality in horses after anaesthesia.

STUDY DESIGN

Prospective clinical study.

ANIMALS

Two hundred and seventy-six equids (110 mares, 85 entire males and 81 geldings), ASA 1-5, weighing 50-850 kg and aged 1 month - 25 years.

METHODS

Recoveries after general anaesthesia were assisted with head and tail ropes by two anaesthetists. One scored dichotomous objective descriptors (DOD) of recovery. Two dichotomous objective scales (DOS) were then generated from those descriptors. The same individual also scored overall recovery quality using a visual analogue scale (VAS). The second anaesthetist scored recovery (good or bad) using a dichotomous subjective scale (DSS). Each DOD, the DSS and VAS were compared with each other using Pearson's chi-square test. DOSs were compared to the DSS using Wilcoxon's test and to the VAS using a Spearman's correlation test.

RESULTS

Most DODs were associated (p < 0.05) with DSS and VAS. The DSS was not associated with resting/not resting in sternal recumbency (p = 0.535) nor with the time spent in sternal recumbency (p = 0.09). VAS and DSS scores were strongly associated (p < 0.0001). The two DOSs were in agreement with DSS (p < 0.0001) and negatively correlated to VAS (r(1)(2) = 0.38, r(2)(2) = 0.34, respectively, p-value <0.0001).

CONCLUSION

Objective descriptors were linked closely with the subjective evaluations of recovery quality except for the presence or absence of a sternal recumbency phase and its duration.

CLINICAL RELEVANCE

These components may not be essential in recovery scoring systems. The DOS were in agreement with DSS and VAS and could be a useful tool for further studies on recoveries.

A comparison of four systems for scoring recovery quality after general anaesthesia in horses

REASON FOR PERFORMING STUDY

The recovery quality scoring systems (RQSSs) in current use have not been critically reviewed for reliability.

OBJECTIVE

To examine reliability (reproducibility) of 4 RQSSs when applied to a ranked series.

METHODS

A DVD incorporating the recordings of 9 horses recovering from general anaesthesia was evaluated by final year students over 5 days. On Day 1, each evaluator ranked recoveries from 1-9 (1 = best). Over the following 4 days, each evaluator scored the same recoveries using 4 different RQSSs (3 of them in common usage and previously published) applied in random order. The scores from each RQSS were ranked and plotted against the Day 1 ranking of each evaluator to establish the extent of agreement using generalisability theory. The same 9 recoveries were also ranked by 12 experienced equine anaesthetists and the Spearman Rank Correlation coefficient calculated to determine the agreement between experienced and inexperienced evaluators.

RESULTS

The recoveries were evaluated by 117 students. All 4 RQSSs were equally reliable with low (<4%) interobserver variability. The main (80%) source of total variation arose from differences between horses. The overall ranking within each RQSS was strongly correlated with Day 1 ranking. There was strong correlation (r = 0.983) between the students' ranking and that established by experienced anaesthetists. Interobserver reliability was similar with all 4 RQSSs.

CONCLUSION

All 4 RQSSs studied were similarly reliable.

POTENTIAL RELEVANCE

The selection of a universally acceptable RQSS from amongst the 4 examined can be based on criteria other than reliability, e.g. ease of use. This will facilitate wider scale multi-centre studies in recovery quality after anaesthesia in horses.

Post anaesthetic colic in horses: a preventable complication?

REASONS FOR PERFORMING STUDY

There is little information on the prevalence of, and risk factors associated with, post anaesthetic colic (PAC) in horses undergoing nonabdominal operations.

OBJECTIVES

To undertake the first prospective study of prevalence of PAC and identify risk factors in its development in nonabdominal procedures.

METHODS

A multicentre prospective case-control study was conducted, on every horse undergoing anaesthesia for a nonabdominal procedure between April 2004 and June 2005. Colic cases were defined as any horse with recognised signs of abdominal pain within 72 h of general anaesthesia that could not be attributed to any concurrent disease. Five control horses per case were selected randomly from the study population at all hospitals. Multivariable logistic regression analysis was used to examine the relationship between predictor variables and the risk of developing PAC.

RESULTS

The estimated mean prevalence of PAC in the study population was 5.2% (95% CI, 2.8, 8.0). However, the prevalence of colic varied between each centre. The most commonly diagnosed cause of colic was impaction. Multivariable analyses showed that the centre involved and the type of surgery performed were associated with an increased risk of PAC. Preoperative food deprivation and the use of opioid drugs were confounding factors.

CONCLUSIONS

Prevalence of PAC varied significantly between the 4 hospitals studied; there may be hospital-related covariates that account for this. The type of surgery performed influenced the risk of PAC.

POTENTIAL RELEVANCE

Identifying the risk factors for PAC is a prerequisite for its prevention. This study indicates horses at increased risk of PAC that might benefit from a more critical evaluation of post anaesthetic gastrointestinal function and/or the provision of preventative measures. Further investigation is required to explain the variation in prevalence of PAC between centres.