CHANGE IN LOCOMOTOR-ACTIVITY PATTERN IN MICE - A MODEL FOR RECOGNITION OF DISTRESS

Recognition and assessment of pain and distress is made by observing c ommon clinical and behavioural signs. Observation usually occurs durin g a limited period of time and results can be biased by interpretation of an individual observer. To improve objective assessment of distres s we studied the locomotor activity pattern of mice during a 24-h inte rval. As a reference compound, Freund's complete adjuvant (FCA) was us ed. Mice were injected intraperitoneally with different doses FCA (0, 0.1, 0.2 and 0.5 mi) and observed for 5 to 7 days. Animals did not app ear to be in pain and seemed to have a normal activity and behaviour p attern at first sight, however FCA induced a dose-dependent decrease o f body weight. Open field activity (total distance run) measured durin g a limited period of time was not altered as a result of FCA. However , nocturnal activity was dose dependently decreased during the first 3 to 4 nights after treatment with FCA. The data presented indicate tha t using locomotor activity patterns over 24 h might be a useful adjunc t and an objective approach to assess distress.