Krall, C., Glass, S., Dancourt, G. et al. 2019. Behavioural anxiety predisposes rabbits to intra-operative apnoea and cardiorespiratory instability. Applied Animal Behaviour Science 221, 104875.

Rabbits are prone to complications from both anaesthesia and anxiety. Given that anxiety can often impact quality of anaesthesia, we developed a novel cage-side anxiety assessment, and sought to determine whether it correlated to pre- and intra-operative cardiorespiratory changes. We examined 31 singly-housed, female New Zealand white rabbits scheduled for a brief experimental ophthalmic surgery using the anxiety assessment, which consisted of behavioural observations, a modified human intruder test, and a novel object test, all performed in the home cage; however, the novel object test was dismissed mid-study when the first group of rabbits tested (n = 14) approached the object in almost equal time. On the day of surgery, in addition to monitoring standard cardiorespiratory parameters, we ranked the ease of intubation, and recorded the frequency of pre- and intra-operative apnoea. Our anxiety assessment produced almost perfect inter-observer agreement (κ = 1.00) and acceptable internal consistency of its tests (α = 0.75). We found that 9 rabbits were behaviourally anxious, and 22 were non-anxious. Anxious rabbits exhibited an increased frequency of intra-operative apnoea (F = 7.03, p = 0.01), and trended towards showing a wider maximum (F = 4.05, p = 0.06) and range of heart rate (F = 3.74, p = 0.07) as compared with the non-anxious group. Additionally, irrespective of anxiety, rabbits that experienced pre-operative apnoea were more difficult to intubate (U = 7.50, p = 0.001). Based upon these results, our anxiety assessment successfully differentiated a sub-population of rabbits that were behaviourally anxious and exhibited cardiorespiratory instability during surgery. This practical cage-side tool can be used as a pre-anaesthetic screen to identify rabbits that may be prone to complications and enable pre-operative intervention. Given that cages are comparatively barren to the natural environment, home-cage novel object tests may be less useful in laboratory species, as the excitement of a new enrichment overcomes potential neophobia. In summary, employing the anxiety assessment as an adjunct to individually planned anaesthesia regimens serves as a refinement to the welfare of rabbits.

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