“…Moreover, physical restraint is often required to obtain these measures leading to a general stress response, further confusing interpretation of the data (see Mormède et al, (2007) for review). Poor nutrition (Ingvartsen and Moyes, 2013;Lean et al, 2013), lack of physical and mental stimulation (Matur et al, 2016;McCreary and Metz, 2016), and disease (Raaperi et al, 2012;Šavc et al, 2016) are also possible causes of changes in general body function making these measures unreliable for pain assessment. Although longer term changes in behaviour can be objectively measured, they reflect the changes between two time-point observations rather than what the animal is experiencing at any particular time (Weary et al, 2006).…”