Table 4.

Example of an enhanced monitoring sheet

Date	Weight (measure fortnightly unless on a downward trajectory)	Note the % weight loss from 15-month starting point	Note all observations: Weight Coat condition General appearance/colour Mobility/movement/hunching General behaviour (e.g. interaction with cage mates/use of bedding/nest making) Genitals External and internal lumps/masses Eye defects Respiration Stools (Check Table 3 for advice to follow)	Note action taken

NB. Commence enhanced health check, score and weigh ageing animals (unless there is information to suggest otherwise) from 15 months of age on a fortnightly basis. This frequency should be increased if the animal gives any cause for concern. Moreover, there is some evidence to suggest that weekly monitoring after the animals' reach 20 months of age is recommended – at least in some strains – as there can be a steep downward trend in their health. After 30 months of age, it is likely that fewer animals will remain alive and that they may require daily enhanced monitoring. The above monitoring frequencies are only a broad recommendation. As you gather more information on your mouse strains, frequencies may be altered to suit your local needs. Monitoring frequency can be influenced by many factors including – but not limited to – the animals’ immediate housing environment (e.g., cage type), strain and genetic background of mice, gender, disease model and study needs. Table 3 lists a number of changes that can be associated with the ageing process, together with suggestions as to how to monitor and/or act upon them. As observed changes accumulate or increase in ‘intensity’, so the frequency of monitoring increases in proportion. It is important to emphasize that there is no perfect tabulated list of clinical signs that can cover all the various possible pathological conditions that animals may develop as they age. In addition, local practices and experience, together with any limitations that may be described in associated project authorization and study design, will necessarily affect the way these conditions are assessed and acted upon.