The African Clawed frog, Xenopus laevis, is an extremely widely used laboratory animal but comprehensive, consensually developed Best Practice (BP) guidelines for housing and husbandry in this species are lacking. Our work will develop an entirely novel, non-invasive, no-contact biochemical assay for measuring corticosterone (stress hormone) in tank water for X.laevis.
We have recently developed and fully validated these methods for Hymenochirus boettgeri (close relative of X. laevis) and used them to detect significantly higher levels of corticosterone release in a more 'stressful' condition compared to a less 'stressful' one. Development of this technique for use with X. laevis will enable non-invasive physiological stress assessment in this species for the first time. The assay would be used to refine the huge variation in a range of key current X. laevis husbandry recommendations by experimentally investigating tank water depth and volume ranges; water change frequency; water temperature and pH ranges and lighting regime to identify conditions associated with lower corticosterone release.
A fully comprehensive ethogram of X. laevis behaviour (also lacking) will be compiled. The behavioural responses of animals will then be directly quantified for different enrichments (physical, social and their interactions) and these correlated with concomitant corticosterone measurements to evaluate these for husbandry use. From this we will develop a novel, non-invasive Behavioural Stress Score (BSS) for this species by using our data to outline a putative scale of behaviours known to be associated with varying degrees of corticosterone release. Comprehensive discussion with X. laevis users (through invited workshops) will enable us to test the potential of this BSS for wide use as a welfare monitoring tool. This work will enable direct refinement of husbandry/housing for this animal and reduction in animal use through improved welfare monitoring and increased re-use.
Holmes AM et al. (2018). Effects of transportation, transport medium and re-housing on Xenopus laevis (Daudin). General and Comparative Endocrinology 266:21-28. doi: 10.1016/j.ygcen.2018.03.015.
Holmes AM et al. (2016). Impact of tank background on the welfare of the African clawed frog, Xenopus laevis (Daudin). Applied Animal Behaviour Science 185:131-136. doi: 10.1016/j.applanim.2016.09.005