Start with the injuries yards actually see
Most yard first aid is not dramatic. It is a cut from a flint in the field, a scraped heel from an overreach in the school, a knocked splint bone, or a shoe pulled half off on a hack. So a horse first aid kit should be built around cleaning and covering wounds and protecting a damaged hoof, not around exotic equipment. The core is wound care: sterile non-stick dressings in a couple of sizes, gamgee or padding, rolls of bandage, cohesive wrap that sticks to itself, and tape to finish the job. Add a large syringe and clean water or saline so you can flush grit out of a cut before you dress it, because a bandage over a dirty wound traps the problem in.
Bandaging, temperature and the basics
Bandaging supplies run out faster than owners expect, so hold more than one of everything: two full leg bandage sets, spare stable bandages, and dressings for awkward spots like heels and knees. A digital thermometer is essential kit, since a raised temperature is one of the first objective signs that a horse is unwell, and a stethoscope is worth having if you know how to take a pulse and listen for gut sounds. Disposable gloves, blunt-ended scissors for cutting bandage away safely, a head torch for dark mornings, and a notebook and pencil round out the working kit. Write the vet's number and the yard address inside the lid, because in a panic nobody remembers a postcode.
The hoof section people forget
Hooves generate a large share of yard emergencies, so give them their own corner of the box. A hoof pick, a rasp if you are confident tidying a ragged edge, and above all a hoof boot or a roll of strong tape and padding to protect a foot that has lost a shoe will save a horse from bruising on hard ground while the farrier is booked. Poultice dressings belong here too, for the classic hot, sore foot that needs drawing and covering overnight. If a horse is hopping lame with heat and a bounding pulse in the foot, that is not a wait-and-see case: protect the foot, keep him on a deep bed, and call the vet the same day.
Where it lives and how it stays ready
A kit only works if everyone on the yard can find it half asleep at dawn. Keep it in a clean, dry, clearly marked box in the tack room or feed room, never buried under rugs, and tell anyone who helps with the horses where it is. Every time something is used, replace it before the next weekend; dressings that ran out during the last emergency are how small cuts become big vet bills. Check the box at the start of each season for perished wrap, flat torch batteries and missing scissors, and restock in one go.
Emergencies are also when a vet starts asking questions — vaccination status, current medication, recent procedures — while you are holding a torch and a lead rope. Keeping each horse's Pet Passport in KinsLe, with those records gathered in one portable packet, means the answers are on your phone instead of in a feed-room folder you cannot find.