Start from the passport, not from memory
The vaccination record in your horse's passport is the source of truth: it shows what was given and when the next booster falls due, and competition and yard rules judge by that page, not by your recollection of the vet's visit. Build the reminder from the due date written there, set a month ahead to leave room for booking, and add a second prompt a week out if the horse competes — a booster given a day late can reset a whole course under strict rules, which is the most expensive diary error in horse keeping.
Teeth run on the horse's age
Dental checks follow the mouth, not the calendar alone. Young horses changing teeth, and older horses whose teeth wear unevenly, usually need checking twice a year; a settled adult in easy work may be fine on an annual visit. Set the reminder by your horse's pattern, and add what the last visit found — hooks beginning on the upper molars, a wave mouth forming — because the finding decides the interval, and the next practitioner will work better knowing it. Note eating changes between checks, such as dropped feed or slow weight loss, as they can pull the next visit forward.
The saddle check follows shape, not dates
A saddle fitted to a horse in spring condition may pinch the same horse by autumn, and a horse returning from rest wears a different back from the one that was competing. Book the saddle check on the annual round, but treat shape changes as triggers in their own right: muscle built over a summer of work, condition lost over a hard winter, a young horse filling out. Reminders keyed to when the rugs change weight or before the season's first long ride catch what a bare annual date misses.
One page per horse, three jobs visible
Keep the three reminders together on the horse's own record rather than scattered through a general diary: booster due, dental due, saddle check due, each with the last-done date beside it. On a multi-horse yard this page-per-horse habit is what stops one horse's jobs being done on another's schedule, and it gives the vet, dentist, and saddle fitter the same history to work from at each visit. Cross off and re-date each job as it is done, so the page always shows the future, not the past.
Stack the visits where you can
The three jobs belong to three different professionals, but the diary can still be kind: a dental visit booked in the same week as the booster saves a second yard trip in many areas, and the saddle check reads best on a horse in current work, so pair it with the start of a training block rather than a rest week. Note in the reminder itself what it should be combined with, so the efficiency is planned rather than stumbled into. Each reminder fires against real dates only if the records sit behind it, and KinsLe's Pet Passport keeps your horse's vaccination, dental, and visit history in one packet so every due date is checked against the facts.