Record the Same Few Things Every Day
A useful diary is boringly consistent. Each day, note what was offered at each meal and roughly how much of it she ate, whether she drank and used the litter tray as usual, and a one-line read on her behaviour: bright, quiet, hiding, clingy, restless at night. Add anything out of the ordinary with the time it happened, such as a vomit, a missed tray, a bout of over-grooming, or a sudden dislike of being touched somewhere. Two honest lines written daily beat a page of impressions reconstructed the night before the appointment, because the vet is looking for sequence and frequency, not prose.
Add the Context That Explains the Entries
Cats react to their environment, and a diary without context sends the vet chasing ghosts. Note the household events alongside the cat's data: visitors staying, a new pet, building noise, a change of food or litter, your own absence for a weekend. When the appetite dip lines up exactly with the builders' visit and resolves when they leave, the diary has done diagnostic work before the vet says a word. Equally, a change with no matching event, building steadily over weeks, is itself important information, and it reads clearly only because the ordinary days around it were recorded too.
Write Observations, Not Conclusions
Describe what you saw rather than what you think it means: 'ate half of breakfast, left the rest, slept under the bed until evening' is usable evidence, while 'seemed depressed' is a guess the vet cannot build on. Quantify where you reasonably can, in meals finished, trays used, and hours hidden, and photograph or briefly film anything hard to describe, such as an odd gait, a scratching pattern, or the sound of a new cough, with the date attached. If you weigh her at home on a regular rhythm, add that too, since gradual weight change is one of the clearest signals a diary can surface.
Know When the Diary Becomes an Urgent Call
Diaries are for patterns, not emergencies, and some entries should trigger a same-day call rather than another day's notes: a cat who stops eating altogether, strains in the tray without producing anything, vomits repeatedly, breathes with effort, or hides suddenly and completely when she is normally social. When you do book in, send or bring the diary itself, flag the entries that worry you, and be ready to say when she was last completely her normal self, because that anchor point helps the vet judge how fast things are moving.
Turn the Diary Into Questions for the Appointment
In the day or two before the visit, read the diary through and convert its patterns into a short list of questions and observations to raise: when the change began, what it coincided with, what has already improved or worsened, and what you most need the vet to rule in or out. Put that list at the front of the diary so the appointment starts with your evidence rather than a scramble to remember. Afterwards, note the vet's findings and any agreed next steps in the same diary, so the following weeks of entries can be read against a professional baseline instead of floating free.
Filing each week's notes into KinsLe's Pet Passport puts your home observations in the same packet you hand across the consulting-room table.