Worm control in horses has moved from worming by the calendar to worming by evidence, and the evidence is the worm egg count. A simple log — sample dates, count results, treatments given, pasture notes — is what turns a drawer of scattered lab reports into a worming programme you can actually defend and adjust.
What the count measures
A worm egg count is done on a fresh dung sample sent to a laboratory or your vet practice, which counts the eggs present and reports a result for that individual horse. It shows which horses are shedding eggs onto the pasture, and horses differ enormously in this: a few individuals typically shed far more than the rest of the herd put together. The count does not reveal every type or every life stage of worm, which is why it informs a programme rather than replacing veterinary advice. What it does superbly is tell you which horses need treatment and which are carrying very little, so treatments go where they will work.
The fields each entry needs
Give every test its own dated entry: the horse, the date the sample was taken, the result exactly as reported, and what was decided on the back of it. Beside the counts, log worming dates in the same record — what was given, as advised by your vet, and to which horses — so treatment and evidence can be read side by side. Add the grazing group and the field, because a count belongs to a horse on a particular pasture with particular companions, and the same horse can return a very different result after a move. Six months later, deciding the next round, that context is the difference between reading a result and guessing at one.
Let the results steer, with your vet
The pattern most yards now follow is targeted: test at intervals through the grazing season, treat the horses whose counts call for it, and test again after treatment where the vet wants to confirm the treatment did its job. A run of low counts for a horse is a finding worth having, because it argues for leaving that horse untreated rather than dosing from habit. Interpretation belongs to the vet, not the log: counts vary with season, age and pasture, and young horses and new arrivals often need a different approach from the established herd. Bring the log to that conversation and it becomes short and specific.
Pasture management belongs in the same log
Egg counts only make sense alongside what you are doing about the pasture itself. Note droppings removal rounds, field rests and rotations, harrowing done in dry weather, and any new horse joining the group, all of which change the egg pressure the next count will meet. When a count surprises you, the pasture notes usually hold the explanation: a rested field comes back cleaner, while a field grazed hard all season does not. Across years, the combined log shows which fields and which routines keep the counts low — and keeping counts low, rather than repeatedly treating high ones, is the real goal.
KinsLe's Pet Passport keeps health records like these together in one portable packet, so counts, treatments and pasture notes are in one place when you sit down with your vet to plan the season's worming.