Choose a few tests you can repeat identically
A useful mobility record is not a diary of impressions; it is the same small set of checks, done the same way, month after month. Pick four or five things your cat actually does: stepping up one step or onto its steps, getting in and out of the litter tray, reaching a favourite low perch, the stiffness of its first steps after a long sleep, and how long it plays before stopping. Score each simply, for example easily, with effort, with difficulty, or not at all, and always test at a similar time of day, because an old cat is stiffer after rest and looser after moving about. Identical conditions are what make two months comparable; without them you are comparing a morning cat with an evening cat.
Add weight, video, and a few honest lines
Numbers and pictures anchor the record. Weigh your cat monthly on the same scales and write the figure down, since weight loss both signals and worsens mobility problems in old cats. Take one short phone video each month of your cat walking across a room and, if it still does, climbing its step; thirty seconds is enough. Video is unsentimental evidence: owners adapt gradually and forget how the cat moved six months ago, while a dated clip shows the change plainly. Finish each month's entry with two or three honest lines on appetite, grooming reach, and anything new, including improvements. A record that only logs decline will miss the months a change of bed, steps, or treatment genuinely helped, and your vet needs to know what worked.
Keep the record where it will actually be kept
The best system is the one still running in month eight. Store entries in one place, in the same format, with the date first, and set a fixed trigger, like the first Sunday of the month, so the habit does not rely on remembering. Whatever the medium, keep the sequence chronological and resist tidying old entries into what you now think was happening; the raw monthly snapshots are the value. If several people care for the cat, one person owns the monthly check while others can add dated observations between times, each attributed, so the record stays consistent rather than becoming three people's conflicting impressions.
Reading the trend, not the day
Single bad days mean little: old cats have off days after a busy household weekend or a cold night. What matters is direction across three or more entries. A step score sliding from easily to with effort to with difficulty over a season is a finding, even if each individual month looked unremarkable. Watch combinations too: mobility slipping alongside weight loss is a different picture from mobility slipping while weight is stable, and both differ from stiffness that improved when the heated bed arrived. Bring the record to every vet appointment and go through it together; vets make better decisions about pain relief, home changes, and further tests from a six-month trend than from a worried summary in the consulting room.
When the record says act now
Some entries should not wait for the monthly rhythm or the next routine check. If your cat stops managing the litter tray, cannot rise without help, cries when moving, or deteriorates sharply within a single month, that entry is a vet appointment, not a data point. The record also earns its keep at that visit, showing exactly when the change began and how fast it moved. Keeping the log in KinsLe's Pet Passport places your old cat's mobility history beside its blood results and visit notes in one portable packet, so the trend you have carefully built is in the vet's hands, not left at home.