How to Prepare Your Horse for the Colder Months

As the grass stops growing, the horse’s diet moves from pasture to hay or haylage, and that is a larger change to the digestive system than it looks from the yard. The hindgut runs on a big population of fibre-fermenting microbes, and that population is tuned to whatever the horse has been eating for the last few weeks. Swap fresh grass for dry conserved forage abruptly and the microbes have to re-sort themselves. In the gap, the horse is more prone to loose droppings and to colic. Work on ponies moved suddenly between grass and hay shows the gut flora starts shifting within a day or two and re-stabilises within a few more, but “re-stabilises” is not the same as “no disruption,” and colic risk is known to rise with any sudden change of feed.

So make it gradual, over two to three weeks. If the horse is stabled at night, start putting hay out in the field while there is still grass, so the ratio tips slowly. If it lives out, bring hay into the paddock early and let the horse choose between that and the dwindling grazing, which has the side benefit of taking pressure off a field that is about to stop recovering.

Forage is also the horse’s own central heating. Fermenting hay in the hindgut throws off a steady flow of heat, far more than the same number of calories fed as hard feed, which is why a horse with hay in front of it around the clock rides out a frost so much better than one on a restricted ration. How much extra to feed in a cold snap, and why an extra section of hay often beats an extra rug, is covered in the rug guide.

It is easy to relax about grazing once the field looks tired, shorter, less green, obviously past its summer best. The sugar content tells a different story. When nights turn cold enough to slow or halt growth while the days are still bright, the plant keeps photosynthesising but cannot spend what it makes, so it stockpiles non-structural carbohydrate, fructan and simple sugars, in the base of the stem. A frost sharpens the effect further: frosted grass can hold a spike of sugar for a day or more, and the level is often highest on a cold, sunny morning.

For a horse or pony that is laminitis-prone, overweight, or has EMS or PPID, that makes a bright frosty autumn one of the higher-risk grazing stretches of the year rather than a lull. The rule of thumb from equine nutritionists is to be cautious about turning such horses onto pasture when nights are dropping below roughly 5 °C and the days are sunny, especially first thing, after a frost. A grazing muzzle, a bare fenced-off “sacrifice” area, or simply turning out later in the day once sugars have fallen are the usual ways to manage it.

Cold, dry, still weather is easy on a horse. Wet is not. Skin that stays soaked for hours softens and loses its barrier, and once that barrier is broken, opportunist organisms (Dermatophilus congolensis among them), move in and produce the scabbing and soreness of mud fever, more properly called pastern dermatitis. Feathered legs, pink-skinned white legs, and any leg that spends its day in a churned gateway are the first to go.

The management is about the water, not the mud. Cut the hours the horse stands in it: rotate the gateway, put hardcore or matting on the worst-worn ground, use a drier sacrifice area through the wettest spells. When legs do get plastered, either let the mud dry and brush it out, or hose it off and then dry the leg thoroughly, a leg left damp under a boot or a layer of barrier cream is worse off than a leg left muddy. Washing every single day keeps the skin permanently soft and makes the problem more likely, not less.

Feet change in the wet too. Permanently damp horn is softer: it holds shoes less well, chips and flares more, and the frog is more prone to thrush. Keep the farrier or trimmer cycle going right through winter instead of stretching it, pick the feet out daily to catch thrush early, and get any hoof-balance problem sorted before the going turns deep, a marginal foot copes far worse in mud. We go into hoof care properly in a separate guide.

One worming job is genuinely tied to the calendar. Small redworm (cyathostomin) larvae burrow into the gut wall in late autumn and lie dormant there through the winter, where a faecal egg count cannot see them. If large numbers emerge together in late winter or early spring, they can do severe damage, sudden weight loss, diarrhoea, colic, occasionally death. The standard response is a single dose of moxidectin in late autumn or early winter, the only licensed single-dose treatment for the encysted stage, timed for when temperatures are consistently falling. Guidance often points to daytime temperatures staying below about 6 °C.

Because this is a treatment a worm-egg count cannot inform, it has traditionally been given on the calendar rather than on a test, though a blood test for small redworm is now available, and a low-risk horse in a well-managed, closed group with a history of low counts may not need dosing at all. Autumn is also the usual point for a tapeworm treatment (praziquantel, or a double dose of pyrantel), ideally guided by a saliva or blood test.