Habituating pigs for in-pen, non-invasive biophysical skin analysis

The purpose of this study was to develop a method for habituating pigs (Sus scrofa domestica, middle white strain) to enable non-invasive, biophysical measurements of dorsal skin to be obtained on a daily basis over a 7-week period, thus eliminating the need for anaesthesia or restraint. This was accomplished by associating measurements of transepidermal water loss (TEWL) and skin reflectance spectroscopy (SRS) with feeding times, and with positive reinforcement by allowing exercise outside the home pen. During the pig habituation period, a well-defined series of behavioural changes were observed that included dominant/ submissive leadership changes. Values of TEWL (6.29 +/- 1.25g.m(-2) x h(-1)) were in agreement with previous studies (7.56+/-2.90g.m 2 x h(-1)) obtained from unrestrained Yucatan hairless micro-pigs (Gabard et al. 1995). The coefficient of variance of TEWL and SRS measurements were comparable with those reported previously using anaesthetized pigs (Chilcott et al. 2000). These data imply that biophysical skin measurements obtained from unrestrained, conscious animals are comparable to those obtained from anaesthetized pigs and therefore, support the use of unrestrained pigs for non-invasive biophysical skin measurements. Habituating animals for in-pen, non-invasive, biophysical measurements has substantial implications for reducing and refining laboratory animal experiments in dermatological research without compromising animal welfare.