Start with the frame of the visit
Write the note before you turn your horse out or mix the evening feeds, while the conversation is still echoing. Open with the date, the practice and the individual vet who came, the reason for the call-out, and who held the horse during the examination. Note whether this was a routine visit, a vaccination booster, a lameness work-up or an emergency, because six months from now the single line "vet came Tuesday" will tell you nothing about why she was there or what she was looking for.
Record the findings, not just the outcome
Work through the horse from nose to tail and write down what was actually checked: heart and lungs listened to, teeth rasped or found sharp, eyes examined, limbs palpated and trotted up, back palpated, digital pulses taken. Record the normal findings as carefully as the abnormal ones. "Heart sounded clear, both hind fetlocks cool and tight, trot-up sound on hard ground" is gold at the next visit, because it proves what has changed and what was always there. If a weight tape reading or a condition score was given, write the number beside the date so condition trends show up across the year rather than living in your memory.
Log everything that was given, done or sent away
Note each vaccination and which diseases it covered, any worming treatment administered, and anything else given during the visit, with a word on what it was for. If blood was taken, droppings collected or a swab sent to a laboratory, write what was sent, where it went and when results are expected, so a result that never arrives gets chased instead of quietly forgotten. If equipment was used — a twitch, sedation for the dentist, hoof testers on a suspect foot — record that too, because the next vet will want to know what this horse needed last time to be examined safely.
Capture the plan in the vet's own terms
Plans dissolve fastest, so write the follow-up instructions while you can still hear them: how many days of box rest or small-paddock turnout were advised, when normal work can resume, what the vet wants rechecked and at what point, and which specific signs mean you should call sooner rather than wait. If the vet used a phrase like "come back if the swelling fills again overnight," write exactly that, not your tidier summary of it. This is also the place to note anything you promised to monitor — appetite, droppings, water intake, the warmth in a particular foot — so the monitoring actually happens.
File it where the horse's story lives
Keep the invoice stapled to the note, and add the small things you mentioned in passing during the visit: that he has been quidding his hay, that the new field companion arrived last week, that his coat has been slow to change. Those details look trivial today and can be the clue that makes sense of a problem later. Storing each visit note in your horse's KinsLe Pet Passport keeps his records together in one portable packet, so a covering vet, a new yard manager or a future owner can pick up his story without a single gap.