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

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

Anesthetic management of a horse with traumatic pneumothorax

A traumatic pneumothorax and severe hemorrhage were present in a mare with a large thoracic wall defect, lung perforation, and multiple rib fractures. General anesthesia was induced to allow surgical exploration. We describe the anesthetic technique, and discuss the management of the ventilatory, hemodynamic, and metabolic disturbances encountered

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

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

Ultrasound and Microbubbles Promote the Retention of Fluorescent Compounds in the Small Intestine

Focused ultrasound (US) is a novel means to increase the passage of medication through the wall of the small intestine. The purpose of this study was to determine whether US and microbubbles (MBs) can facilitate delivery of macromolecular therapeutic agents across the intestinal epithelium in vitro and in vivo. In vitro experiments involved delivery of compounds across a cell monolayer, namely Caco-2 cells cultured on ThinCert filters. The cells were cultured for a minimum of 3 weeks to mimic the polarised intestinal epithelium. A suspension of dextran with or without MBs, prepared in growth medium, was introduced into the apical chamber of the ThinCert with a syringe pump through a channel in the centre of a miniature focused US transducer (4 MHz, 1 MPa PNP). Each in vivo experiment involved a tethered endoscopic capsule with an US transducer and a delivery channel inserted into the small intestine of a terminally anaesthetised pig via a surgical stoma. The amount of fluorescent dextran delivered across the Caco-2 monolayer when employing US, MBs and dextran was higher than the amount delivered with dextran alone. With this approach, fluorescent marking of the wall of the small intestine was achieved in vivo by applying US and MBs. Our work indicates that US has potential for application in targeted treatment of gastrointestinal disease and oral drug delivery

Integrated Front End Circuitry for Microultrasound Capsule Endoscopy

Video capsule endoscopy (VCE) was originally developed to address the limitation of conventional endoscopy in accessing the small bowel as a remote part of the gastrointestinal tract. To further enhance the diagnostic ability of VCE, microultrasound capsule endoscopy is under development for identification of disease at an earlier stage and visualisation of subsurface tissue features. This paper presents an evaluation of two approaches to improve signal to noise ratio (SNR) in rapid prototyped capsule endoscopes. First, noise reduction techniques are applied to the integrated front-end circuits in the prototype capsules. Secondly, multiple types of coded excitation transmission are tested and benchmarked with respect to non-coded transmission. Results are presented for both bench top phantom imaging and in vivo translational trial imaging