Decide what a good life still looks like for him
The heart of the plan is a definition, agreed while he is well: what does a good life look like for this horse, and what changes would mean it is no longer good? Sit down with your vet — ideally on a routine visit, not in a crisis — and talk it through in his terms. For most horses the honest markers are variations on a short list: he can get down to rest and up again without a struggle; he can eat enough to hold condition; his pain is controlled at a level where he still grazes, moves and takes an interest; and he still seeks out his herd and his routines. Write your markers down. They will not make the decision for you, but on the hardest day they answer the cruellest question — am I doing this too early, or too late? — with words you chose in a calm season, not in a stable at midnight. Decide, too, who makes the final call if you cannot be reached, and make sure that person knows.
The practical arrangements to settle early
A horse's size makes his end of life a logistics problem as well as an emotional one, and logistics go badly when arranged in grief and haste. Talk to your vet practice about how euthanasia is handled for your horse — where it would happen, who attends, and what they advise for him — so the day holds no surprises beyond the ones it must. Then settle what happens afterwards, because collection and disposal cannot wait: find out which services collect fallen stock or offer cremation locally, what they need from you, and whether burial on your own land is permitted under local rules, which vary. If you keep him at livery, tell the yard owner the plan; they will know about access, timing and what has worked on the yard, and nobody should be learning your wishes while a lorry waits. Keep the phone numbers and his paperwork in one known place, not in the memory of the one person who may be in pieces.
Money, people and the other horses
End-of-life care for a horse is not cheap, and guessing at the day is worse than knowing in advance: ask the questions early, get honest figures from your vet and the collection or cremation services chosen, and set money aside, or confirm what any insurance you hold covers. Money decided in advance is one whole layer of distress removed from the day. People need planning too. Tell the family, the friend who shares him, the staff who muck him out, what the plan is and what your markers are — the kindest yards are the ones where everyone hears the news from you rather than through the gate. And plan for the horses left behind: his companion will grieve in his own way, and many owners find that letting the companion see and smell him afterwards settles the herd faster than a horse who simply vanishes. Arrange his companion's company and routine for the days after, so no animal on the yard faces an unexplained absence alone.
Afterwards: grief on a yard and keeping his story
Give thought now to the small things that are unbearable to improvise: whether you will keep a lock of his tail, his shoes, his nameplate; whether his stable stands empty a while or is filled quickly; what happens to his tack and rugs. There are no correct answers, only kinder ones chosen in advance. The empty stable door and the head over it that is not there will hurt regardless; what planning removes is the administrative cruelty of forms, payments and phone calls competing with that hurt. Keep his story as deliberately as you kept his records: the photographs gathered, and the tale of how he came to you written down while the tellers still remember the details. KinsLe Memorial Accounts give that story a permanent home — his photos and his history held in a profile the family and the yard can visit — so the horse you planned so carefully for is remembered with the same care, long after his nameplate comes down.