When to rug a horse, and how to tell if your horse is actually cold

Rug a horse when that particular horse needs help keeping warm: it is clipped, old, thin, unwell or fine-coated, or it faces cold wind and rain without shelter. A healthy horse with a full winter coat, plenty of forage and somewhere to shelter often needs no rug at all, even in October.

That is not how most of us decide. The first cold morning arrives, we pull on a second jumper, and the medium-weight comes out of the rug room. It is a kind instinct, and the evidence suggests it often points the wrong way.

This post covers why horses feel cold differently from us, how to check your own horse properly, the signs of over-rugging, and the factors that genuinely change the answer.

When should you rug a horse?

When the horse in front of you needs it, which depends far more on the horse and the weather than on the date. The British Horse Society’s rugging guidance puts it plainly: horses typically stay comfortable without a rug until the temperature drops below about 5°C, and many horses, especially natives and cobs, manage winter without one when they are healthy, have enough forage and can get out of the weather.

So the question is never really “is it cold today?”. It is three questions:

1. Is this horse less able to keep itself warm? Clipped, elderly, underweight, unwell or fine-coated horses are.
2. Is the weather wet and windy, not just cold? That matters more than the number on the thermometer.
3. Has it got forage and shelter? Hay, haylage or grass is a heater, and a hedge or a field shelter takes the edge off the wind.

If the answer to all three is no, the horse probably doesn’t need a rug yet. If one is yes, a rug may help, and the next question is how much.

Do horses feel the cold the way we do?

No, and this is the root of most over-rugging. Every animal has a range of outside temperatures in which it keeps its body warm without spending extra energy, called the thermoneutral zone. Redwings puts a horse’s at between 5 and 25°C, against roughly 18 to 30°C for people. World Horse Welfare gives the same 5 to 25°C range. So the day that sends you for a coat is often well within your horse’s comfortable range.

The lower end is not fixed, either. A 2022 review and survey in the Australian Veterinary Journal notes that the point at which a horse starts needing extra energy to stay warm can be below 5°C in horses not used to a cold winter, and as low as minus 15°C in mature horses living outdoors through a Canadian winter. A horse that has grown its coat and adapted over the autumn copes with far more than one that has been rugged since September.

Horses have their own heating system, too:

• The coat. Redwings describes how the hair lifts and even rotates to trap warm air against the skin like a duvet. Snow sitting unmelted on a horse’s back is a sign the coat is insulating well, not that the horse is freezing.
• Digestion. Breaking down fibre in the hindgut produces heat, which is why forage matters more on a cold night than an extra layer.
• Movement and shelter. A horse that can move around and choose where to stand looks after itself well.

That same Australian survey of more than 2,600 horses found 84.8% were rugged, yet 69.5% of owners weren’t sure their horse needed a rug at all, and 21.4% of horses were still rugged above 20°C. It was a self-selected online survey from a warmer country, so treat the exact figures with care. The pattern of rugging for our own comfort rather than the horse’s is familiar on British yards too.

How can you tell if your horse is actually cold?

Feel the horse, not the air. The BHS suggests sliding a flat hand under the rug behind the withers: the horse should feel comfortably warm and dry, not cold and not sweaty. On an unrugged horse, feel the body over the shoulder and along the neck under the mane.

Don’t judge by the ears or legs alone. They are the extremities, the parts a horse lets cool first while it keeps its core warm, so cold ears on a frosty morning are not, on their own, a horse asking for a heavier rug.

Signs a horse is genuinely cold include:

• Shivering, especially if it lasts for minutes at a time
• Tail clamped tightly against the hindquarters
• A tucked-up stance, back hunched and legs drawn under
• Actively seeking shelter, or standing with its back to the weather
• Pacing or restlessness in the field
• Gradual weight loss over the weeks, which is the slow version of the same message

One check tells you very little. A horse that shivers briefly in a squall and then gets on with grazing is coping. A horse that is tucked up and shivering at the gate every time you arrive is telling you something.

How do you know if your horse is over-rugged?

Over-rugging is the more common mistake and the easier one to miss, because the horse looks snug. The BHS lists these signs:

• Sweating under the rug, or warm, damp skin and a damp coat when you feel underneath
• Faster or heavier breathing than usual at rest
• Rubbing, or a horse that is restless and itchy under its rug
• Lethargy or irritability

A sweating horse needs a lighter rug or none, never a heavier one. A damp coat under a rug loses its insulation and chills as soon as the weather changes or the rug comes off. If you know your horse’s normal temperature, pulse and breathing, they are a useful cross-check here: a horse cooking under too heavy a rug on a mild day can run warm, which our guide to normal horse TPR covers.

Watch the forecast as well as the horse. A rug that is right for a frosty night is often far too much by lunchtime on a sunny October day, and Redwings notes there is no need to keep a horse rugged continuously through winter.

Which horses are more likely to need a rug?

These are the factors the BHS, Redwings and World Horse Welfare all point to. There are no temperatures in this table on purpose: published rug-weight charts are commercial rules of thumb, not science, and the factors below change the answer far more than one number can.

A horse can sit in both columns at once. A clipped cob that is also a good doer needs a rug to replace the coat you took away, but probably a lighter one than you would reach for on instinct.

Why do wind and rain matter more than the temperature?

Because the coat works by trapping air, and rain and wind both stop it doing that. Rain flattens and soaks the hair so it can no longer hold warm air against the skin. Wind strips heat from the surface faster. The BHS notes that wind chill and prolonged rain are a greater risk than dry cold.

Research points the same way. A Norwegian study of 22 horses given free choice between staying outdoors and using a heated or unheated shelter, published in the Equine Veterinary Journal in 2016, found the horses spent most time outside on dry days below 0°C and sought shelter most on days with rain or sleet. Shivering was only seen on mild days with rain or sleet, not on the cold, dry ones.

So a 9°C day of driving rain can be harder on an unclipped horse than a still, frosty morning at minus 2°C. That is the day a waterproof rug, or a shelter, earns its keep.

Prolonged wet also matters for the skin. Redwings lists sores across the shoulders, back and rump, which can be rain scald, as one of the signs a horse isn’t coping with the weather. The legs have their equivalent in winter mud, which our post on mud fever prevention and treatment covers.

Why can over-rugging be a problem for good doers?

Because for a horse carrying plenty of condition, losing a little weight over winter is part of the natural yearly cycle, and often a helpful one. Keeping warm costs energy. A horse that is rugged so it never spends any keeping itself warm holds on to the weight it would otherwise have lost, and goes into spring grass heavier than it should be.

World Horse Welfare lists your horse’s fat score and weight management needs first among the things to consider before rugging, and the BHS warns that over-rugging overweight horses increases the risk of laminitis. For a native pony, a cob or any horse with a history of laminitis, a winter that is a bit leaner is part of the management, not a failure of it. Our guide to the early signs of laminitis covers what to watch for.

Fat scoring by hand, every couple of weeks through winter, is the honest way to know which way your horse is heading. A rug can hide a horse that is dropping weight just as well as it can stop one losing weight it needed to lose.

When should you call the vet about a horse in cold weather?

Most rugging decisions are judgement calls you can adjust day by day. These are not. Ring your vet if your horse has:

• Persistent shivering, lasting minutes at a time, that doesn’t settle with shelter, forage or a rug
• Rapid weight loss, noticeable over days or a couple of weeks rather than a gentle winter trend
• Sores, scabs or tufted hair across the shoulders, back or rump
• A change in demeanour: dull, withdrawn, not interested in its surroundings
• Gone off its food or water, or shows any sign of colic
• Sweating heavily with no obvious cause, rugged or not

Call sooner for an elderly horse, a horse with poor teeth or a known medical condition, or one that has been clipped and turned out without enough protection. If you are unsure, that is a reason to call.

Not every shivering, stiff horse in an autumn field is cold. Muscle trembling, stiffness and brown or dark red urine in a horse at grass are signs of atypical myopathy, which is caused by sycamore seeds and is an emergency. A rug is not the answer to that one: ring the vet straight away.

Where the technology fits

Honestly, not much. Deciding whether to rug is your hand under a rug, a look at the forecast and knowing your horse. Stride has no rug planner, no weather feed and no alert telling you to change rugs, and nothing in it decides whether your horse is cold.

What it can do is help with the slow part of the question: whether your horse’s condition is moving the right way over winter.

• The Body & Condition scan takes a side-on photo and gives an estimated body condition score out of nine, kept as a trend alongside earlier scans. It is an estimate from a picture, so treat it as a prompt to fat score by hand, not a replacement for it.
• Observations let you log sweating, off food and other things you notice, with a mild, moderate or marked severity and the date, so a run of sweaty mornings under the medium-weight shows up as a pattern rather than a vague memory.
• Notes and vet records keep the rest together, so a weight check or a vet visit about rain scald sits on the same timeline as everything else.

It is a record, not an adviser. The decision stays with you and, when it matters, your vet.

If you take one thing from this: before the rug goes on this week, put your hand under the old one, or on the horse, and feel what it is actually telling you.