Losing Weight Over Winter: What to Check When Hay Alone Isn't Enough

Winter weight loss is one of those problems that creeps. The rugs go on in November, the coat thickens, and by February you run a hand along his side and find more ribs than you remember. He's had hay all along. So what happened?

Usually it's one of five things, and often two of them at once: not enough forage, higher energy demand from cold, a mouth that can't chew properly, a parasite burden, or an underlying illness. Work through them in that order and you'll find most cases.

A winter coat is an excellent liar. Hands and a weigh tape tell the truth.

Start with the maths, not the haynet

"He's getting hay" is not a quantity. Most horses need roughly 2 to 2.5 per cent of their bodyweight in forage dry matter each day, and a horse who is already losing condition needs to be at the top of that, or above it. For a 500kg horse that's around 10–12.5kg of dry matter — and because hay is only about 85–90 per cent dry matter, that means weighing out more like 11–14kg of actual hay.

Buy a cheap luggage scale and weigh a few nets. Owners almost always overestimate. Then account for what never reaches his stomach:

• Hay trodden into mud or blown across the field doesn't count as fed.
• Soaked hay loses some soluble nutrients — useful for a laminitis-prone pony, unhelpful for one who is dropping weight.
• Very small-holed nets can slow a slow eater below the intake he actually needs. Great for the good-doer, counterproductive here.

Quality matters as much as quantity. Late-cut, stalky, bleached hay can carry far less digestible energy than soft, leafy, early-cut hay, even though the bales look identical on the trailer. If you can, get a forage analysis; if not, compare how fast he clears it and how much he leaves. And remember that hay is not grass. Even good hay generally has less energy than spring and summer grazing, so a horse who holds his weight beautifully in June can slide once the field stops growing.

Cold genuinely costs calories

Below a certain temperature — the lower critical temperature, which varies with coat, clipping, condition and acclimatisation — a horse starts burning extra energy simply to stay warm. Wind and driving rain push that threshold higher, because a wet, flattened coat insulates badly.

Fibre is the best heater you have. Fermentation in the hindgut produces warmth over hours, which is why ad-lib hay in a cold snap beats an extra scoop of hard feed. Beyond that, look at the practical side: is he clipped and under-rugged? Is his rug soaked through or rubbing? Is there any shelter from the prevailing wind, natural or built? A thin horse has less fat insulation, so he gets cold faster, so he loses more — it compounds quickly.

Look in his mouth

Hay demands far more chewing than grass, so dental problems show up in winter. Sharp enamel points, loose or missing teeth, diastemas packing with food, or the worn-down molars of an older horse all make long-stem hay hard work.

Signs to watch for: balls of half-chewed hay dropped on the floor (quidding), slow eating, head-tilting, hay packed in the cheeks, a sudden preference for the softest part of the bale, or droppings full of long fibre lengths. A horse can also have a painful mouth and show almost none of this, which is why an annual check by a vet or qualified equine dental technician matters — twice yearly for veterans.

If his teeth can't manage hay, swap some of it for a soaked short-chop replacement: unmolassed beet pulp, soaked grass nuts, hay cubes or a senior mash, fed in several meals a day to replace the forage he can no longer chew.

Water, worms and herd politics

Horses drink less when water is icy, and a horse who drinks less eats less dry forage — which costs condition and raises impaction colic risk. Break ice at least twice daily, and offer warmed water if you can; many horses will take noticeably more.

Then parasites. A faecal worm egg count won't detect encysted small redworm or tapeworm, so talk to your vet or an SQP about a targeted winter plan including a tapeworm test or treatment and, where appropriate, a larvicidal treatment. A heavy burden can cause weight loss, poor coat and intermittent diarrhoea even in a horse who looks bright.

Finally, watch who actually eats. Stand at the field for twenty minutes at feeding time. The quiet one gets moved off the pile again and again, and if there are three horses and three piles, the bottom horse never settles. Put out more piles than horses, spread them well apart, and consider feeding him separately.

When weight loss is a symptom, not a sum

If forage, teeth, worming and herd dynamics all check out — or if he's losing weight fast — think illness. Common culprits include PPID (equine Cushing's disease), especially in horses over fifteen, often alongside a long curly coat, delayed shedding or laminitis; gastric ulcers, with picky eating, girthiness or a dull coat; chronic pain, which quietly suppresses appetite; and liver, kidney or malabsorptive disease. In older horses, weight loss can be the first visible sign of something serious.

Putting it back on, sensibly

Forage first, always: more of it, and better quality, before you reach for a bucket. Then build calories gradually over one to two weeks — sudden changes upset the hindgut.

1. Add a conditioning feed or soaked beet pulp fed at the manufacturer's recommended rate, split into two or more small meals.
2. Consider alfalfa for extra calories and natural buffering, unless your vet has advised against it.
3. Oil is energy-dense; introduce it slowly and in modest amounts, and check it suits his overall diet.
4. Make sure a balancer or broad-spectrum supplement is covering vitamins and minerals, which winter forage often lacks.

Measure, don't eyeball. Weigh tape on the same day each fortnight, at the same time relative to feeding, and body condition score with your hands under the hair. Write it down. Progress on a thin winter horse is slow and undramatic, and a notebook is the only thing that will tell you whether what you've changed is working.

Aim for steady, not spectacular. A horse who comes out of winter half a condition score down but bright, worm-tested, with sound teeth and a plan is in far better shape than one who was force-fattened in March.