IntroductionAchieving a secure airway in rabbits is generally considered more difficult than in cats or dogs. Their relatively large tongue, small oropharyngeal cavity and glottis limit direct visualization. A rabbit-specific supraglottic airway device (SGAD) may offer benefits over blind orotracheal intubation.Animals and methodsFifteen adult New Zealand white rabbits were randomized to SGAD or orotracheal intubation (ETT). All animals were sedated with dexmedetomidine (0.1 mg kg−1 IM) and midazolam (0.5 mg kg−1 IM), followed by induction with alfaxalone (0.3 mg kg−1 IV). Two CT scans of the head and neck were performed, following sedation and SGAD/ETT placement. The following were recorded: time to successful device insertion, smallest cross-sectional airway area, airway sealing pressure, and histological score of tracheal tissue. Data were analyzed with a Mann–Whitney test.ResultsTwo rabbits were excluded following failed ETT. Body masses were similar [ETT; n = 6, 2.6 (2.3–4.5) kg, SGAD; n = 7, 2.7 (2.4–5.0) kg]. SGAD placement was significantly faster [33 (14–38) s] than ETT [59 (29–171) s]. Cross-sectional area (CSA) was significantly reduced from baseline [12.2 (6.9–3.4) mm2] but similar between groups [SGAD; 2.7 (2.0–12.3) mm2, ETT; 3.8 (2.3–6.6) mm2]. In the SGAD group, the device tip migrated into the laryngeal vestibule in 6/7 rabbits, reducing the CSA. ETT airway seals were higher [15 (10–20) cmH2O], but not significant [SGAD; 5 (5–20) cmH2O, p = 0.06]. ETT resulted in significantly more mucosal damage [histological score 3.3 (1.0–5.0)], SGAD; 0.67 (0.33–3.67).ConclusionThe SGAD studied was faster to place and caused less damage than orotracheal intubation, but resulted in a similar CSA.

There is a growing interest in the use of voluntarily displayed ongoing behaviours in laboratory animals to assess the pain experience. In rats, two behavioural pain scales, the Rat Grimace Scale (RGS, a facial expression scale) and a composite behaviour score (CBS, a behavioural ethogram reliant on postural changes), are both promising pain assessment methods. Both scales have been used to assess pain in a laparotomy model, however, they have never been compared directly and the knowledge of how different analgesics may affect these two scales is limited. This study aimed to provide a comparison to discriminate the temporal and analgesic response in a laparotomy model. Female Wistar (n = 26) and Sprague Dawley rats (n = 26) were block randomized to receive saline, meloxicam (2 mg/ kg) or buprenorphine (0.05 mg/kg) 30 minutes before laparotomy. Rats were video-recorded before surgery (BL) and at 30, 150, 270, and 390 minutes post-operatively. Videos were assessed according to both scales by a trained, blinded observer. Both CBS and RGS scores increased significantly at all post surgical timepoints in the saline group. Both buprenorphine and meloxicam reduced CBS scores to baseline levels following laparotomy; however, RGS scores were only reduced following buprenorphine. RGS scores in the meloxicam group remained similar to scores of the saline group. These findings suggest that the CBS and RGS differ in their sensitivity to discriminating analgesic effects.

Rabbits have a high rate of anaesthesia-related death compared with other companion animal species. This is influenced by a variety of factors, one of which is difficulty in obtaining a secure airway. The rabbit in this report was enrolled in a larger non-survival study that required orotracheal intubation to be performed. Orotracheal intubation was difficult, taking 306 seconds, compared with a median of 134 seconds (range 29–171 seconds) in the four preceding rabbits. Necropsy examination revealed a faecal pellet lodged in the caudal oropharynx abutting compacted faecal material, ventral to the epiglottis. Two structures of mixed gas and soft tissue attenuation were seen on CT scans obtained pre- and post-intubation, at a location consistent with the faecal material, thus confirming the presence of the pellets at the time of sedation and during intubation. Oral prehension of faecal pellets before anaesthesia represents a previously unreported obstacle to orotracheal intubation in rabbits.

22There is a growing interest in the use of voluntarily displayed ongoing behaviours in laboratory 23 animals to assess the pain experience. In rats, two behavioural pain scales, the Rat Grimace Scale 24 (RGS, a facial expression scale) and a composite behaviour score (CBS, a behavioural ethogram 25 reliant on postural changes), are both promising pain assessment methods. Both scales have been 26 used to assess pain in a laparotomy model, however, they have never been compared directly and 27 the knowledge of how different analgesics may affect these two scales is limited. This study 28 aimed to provide a comparison to discriminate the temporal and analgesic response in a 29 laparotomy model. Female Wistar (n = 26) and Sprague Dawley rats (n = 26) were block 30 randomized to receive saline, meloxicam (2 mg/kg) or buprenorphine (0.05 mg/kg) 30 minutes 31 before a laparotomy model. Rats were video-recorded before surgery (BL) and at 30, 150, 270, 32 and 390 minutes post-operatively. Videos were assessed according to both scales by a trained, 33 blinded observer. Both CBS and RGS scores increased significantly at all post surgical 34 timepoints in the saline group. Post-surgical CBS scores did not increase significantly above 35 baseline levels in the groups given meloxicam or buprenorphine. However, the RGS scores only 36 remained low in the buprenorphine group while scores increased significantly in the meloxicam 37 group, to a similar degree as in the saline group. These findings suggest that the CBS is more 38 sensitive to the analgesic effects of NSAIDs than the RGS. 39 Introduction 40Accurate and reliable pain assessment in laboratory rodents is essential to produce high 41 quality pain research and safeguard animal welfare. The continued dependence on evoked 42 hypersensitivity to assess pain in animals has been proposed as a contributor towards failure of 43 translational research. While measures of evoked hypersensitivity assess hyperalgesia and 44 allodynia, they do not capture ongoing pain which has been suggested to be most relevant in 45 many human pain conditions [1][2][3][4][5]. Ongoing pain is perpetuated by an ongoing inflammatory 46 process rather than an external stimulus. Multiple methods have been proposed to evaluate 47 ongoing pain in animals, however, a lack of evidence describing the strengths and weaknesses of 48 such methods in comparison to one another discourages their use [3]. 49From a welfare perspective, signs associated with pain are common humane endpoints in 50 rodent research, but typical signs such as weight loss may not be specific to pain or sufficiently 51 sensitive to be useful [6]. Traditional nociceptive tests, such as mechanical withdrawal testing, 52 are not used as welfare assessment tools as they are time consuming and labour intensive. 53 Two promising behavioural assessment methods have been developed to better capture 54 the ongoing pain experience of laboratory rodents. These are the Rat Grimace Scale (RGS) [7] 55 and the short form Composite Behaviour Sc...

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