Development of incident severity classification for laboratory animals.

An incident reporting system (IRS) prevents possible adverse events by collecting and analyzing incidents that occur. However, few studies are available regarding IRSs in the laboratory animal field. This study aimed to develop an incident severity classification for laboratory animals (ISCLA) to evaluate the usefulness of the IRS in laboratory animal facilities. Twenty-three incidents reported from March 2019 to February 2020 on our IRS were retrospectively reviewed. Three of the 23 incidents failed to obtain some experimental data. Two of these incidents were harmless to animals, but the other caused the animals moderate distress. In addition, two of the three incidents made animals unsuitable for experiments. Since the inconsistent impact of incidents on animals and experiments prevented the comparison of the severity of individual incidents, we developed the ISCLA. According to the ISCLA, the above three incidents were classified into Category 3b and 4a. The others were classified into Category 0 (n=5), 1 (n=6), 2 (n=3), and 3a (n=6) in ascending order of severity. No incident was classified into Category 4b and 5. Furthermore, incidents occurring in the animal housing area were more severe than those occurring in the supporting area (P=0.002). This study showed that incident occurrences had characteristics that were not visible from individual incidents alone. Moreover, the ISCLA was considered useful when conducting the IRS and taking improvement measures in laboratory animal facilities.