Winter Colic in Horses: How to Prevent Impaction During Cold Weather

By Dr Duncan Houston

Cold weather does not directly cause every case of colic. The real winter danger is what changes around the horse: frozen water, reduced drinking, dry hay replacing moisture-rich pasture, less turnout, altered routines and sudden feed changes.

These changes can gradually dry and compact intestinal contents, increasing the risk of impaction colic. The horse may initially look slightly quiet, eat more slowly or produce smaller, drier manure before showing obvious abdominal pain.

The key is not simply keeping your horse warm. It is keeping water available, forage consistent and the gut moving.

Quick Answer

Winter can increase the risk of impaction colic when horses drink less, lose access to water because of ice, eat more dry forage or experience abrupt changes in diet and activity. However, research has not consistently shown that a sudden temperature change itself directly causes colic.

Provide unlimited clean water, ideally between 45°F and 65°F (7°C to 18°C), monitor actual intake and manure production, make feed changes gradually and maintain safe turnout or movement. Any horse showing abdominal pain should be discussed with a veterinarian promptly. (Horse Report)

When Is Winter Colic an Emergency?

Any suspected colic deserves a call to your veterinarian. Mild signs do not always mean a mild intestinal problem, particularly in older or naturally stoic horses.

Seek urgent veterinary help if your horse has:

• Repeated lying down, rolling or getting up

• Violent rolling or thrashing

• Persistent pawing or flank watching

• Sweating without exercise

• Rapid or worsening abdominal swelling

• Little or no manure production

• Very dry or mucus-covered manure

• Refusal to eat or drink

• Pale, dark red, purple or tacky gums

• Rapid breathing or a markedly increased heart rate

• Pain that continues for more than 15 to 30 minutes

• Pain that returns after medication

• Weakness, collapse or inability to stand

• Suspected grain overload or ingestion of foreign material

The severity of the visible pain does not reliably identify the cause. A horse with a strangulating obstruction may initially show only mild discomfort, while another horse with gas colic may appear extremely dramatic. That is why waiting for the horse to become violently painful is a dangerous strategy. (University of Minnesota Extension)

Does Cold Weather Really Cause Colic?

The answer is more nuanced than “cold weather causes colic.”

Horse owners and veterinarians frequently notice cases around cold snaps, storms and sudden seasonal changes. However, research has not consistently demonstrated that temperature change alone directly causes colic.

The more likely explanation is that cold weather changes management and behaviour:

• Water freezes or becomes unpleasantly cold

• Horses drink less

• Moist pasture is replaced with dry hay

• Turnout decreases

• Horses spend longer periods standing in stalls

• Hay or grain quantities change

• New hay batches are introduced abruptly

• Automatic waterers or pipes stop working

• Older horses struggle to chew coarse winter forage

In other words, the thermometer may start the chain of events, but reduced water intake, diet changes and confinement are the more important clinical concerns. (Horse Report)

What Is Impaction Colic?

Impaction colic occurs when feed material becomes excessively dry, compacted or difficult to move through part of the gastrointestinal tract.

The large colon is a common site, particularly the pelvic flexure, where the bowel narrows and changes direction sharply. Impactions can also affect the small colon, caecum, stomach or small intestine. (Today's Veterinary Practice)

Risk increases with:

• Reduced water intake

• Abrupt changes in water availability

• Coarse or poorly digestible forage

• Poor dental function

• Reduced activity

• Sudden diet changes

• Foreign material or bedding consumption

• Parasite burdens in some horses

• Certain medications or illnesses that reduce intestinal movement

An impaction may begin with mild, intermittent discomfort. The horse might eat less, drink less, pass fewer droppings or produce small, dry manure balls. Pain can become more persistent as the obstruction enlarges and gas accumulates behind it. (Today's Veterinary Practice)

Why Water Is the Biggest Winter Concern

A typical 1,000-pound or 450-kilogram adult horse commonly needs at least 10 to 12 gallons, or approximately 38 to 45 litres, of water each day. Requirements increase with exercise, lactation, salt intake, larger body size and some diets. (University of Minnesota Extension)

Winter can create a double problem.

First, horses may voluntarily drink less when water is extremely cold. Second, winter diets usually contain far less moisture than pasture. Lush grass may contain 60% to 80% water, while hay and grain generally contain less than 15%. A horse moved from pasture onto hay therefore needs to obtain more of its water directly from buckets or troughs. (University of Minnesota Extension)

Poor intake may gradually reduce faecal moisture, allowing intestinal contents to become drier and harder to move. This commonly develops over several days rather than after one missed drink, which is why subtle changes in manure and water intake matter. (University of Minnesota Extension)

What Temperature Should a Horse’s Water Be in Winter?

Water between 45°F and 65°F, or approximately 7°C to 18°C, is generally recommended during cold weather.

In one controlled pony study, water consumption increased when water within this temperature range was the only available source, compared with water at 38°F or colder. University of Minnesota guidance reports an increase of approximately 40% under those study conditions. (University of Minnesota Extension)

This does not mean every horse refuses cold water. Some horses will choose colder water when offered a choice. The important point is that total intake may fall when the only source is close to freezing.

Practical options include:

• Heated buckets

• Heated troughs

• Stock-tank de-icers

• Insulated buckets

• Adding warm water to a bucket several times daily

• Carrying warm water from the barn during severe freezes

Water should remain available continuously. A brief opening broken into an iced-over trough may refreeze quickly and should not be considered reliable all-day access. (Veterinary Health Center)

Check Heated Waterers for Electrical Problems

A heated bucket or automatic waterer is only useful if the horse is willing to approach it.

Damaged wiring, poor grounding or stray electrical current can cause a horse to avoid a water source even though it appears full and unfrozen. Check cables, plugs and heating elements regularly, use appropriately protected electrical systems and investigate immediately if several horses suddenly stop using a particular trough. (University of Minnesota Extension)

The machine can be working perfectly while the horse has quietly decided it is an electrified portal to the underworld.

Do Not Rely on Snow for Water

Snow should not be treated as a routine replacement for drinking water.

Some cold-adapted horses have met part of their requirements from snow under specific conditions, but this depends on the snow’s water content, the horse’s adaptation and the moisture contained in the rest of the diet. Eating snow is also a much slower way to consume water.

Domestic horses eating dry hay should still have continuous access to clean, liquid water. (University of Minnesota Extension)

How Can You Tell Whether Your Horse Is Drinking Enough?

Do not judge hydration by whether the trough still contains water. A large trough may hide a significant reduction in an individual horse’s intake.

Monitor:

• The amount disappearing from buckets each day

• Whether automatic waterers are functioning

• How often the horse approaches the water

• Appetite

• Number and size of manure piles

• Manure moisture

• Gum moisture and colour

• Urine quantity and concentration

• Behaviour and energy level

Marking buckets, measuring refills or using a water meter can provide much better information than guessing.

Dry or tacky gums, sunken eyes, reduced skin elasticity and concentrated urine may indicate dehydration, but these signs can appear only after the deficit is already meaningful. Changes in drinking, appetite and manure production are often earlier practical clues. (ANSCI)

Should You Add Salt to Encourage Drinking?

Horses require sodium and chloride, and a free-choice salt source should normally be available. Loose salt may be easier for some horses to consume in winter than a very cold, hard salt block. (University of Minnesota Extension)

Some horses may benefit from a measured amount of salt added to feed, but the correct amount depends on body size, total ration, work, sweat loss and health status. Discuss deliberate supplementation with your veterinarian or equine nutritionist.

Important safety rules include:

• Ensure unlimited water is available

• Do not force concentrated electrolytes into a dehydrated horse without veterinary advice

• Do not assume a winter horse automatically needs performance electrolytes

• If electrolytes or salt are placed in drinking water, provide a separate bucket of plain water

Electrolyte-flavoured water can actually reduce intake if the horse dislikes the taste. (Merck Veterinary Manual)

Can You Flavour the Water?

Some horses will drink flavoured water more readily, especially when travelling or encountering unfamiliar water.

Apple flavouring, a small amount of the horse’s regular feed mixed into water or another familiar flavour may help an individual poor drinker. Introduce the flavour at home before depending on it during travel or a cold-weather event.

Always provide plain water as well. Flavouring is a tool for a particular horse, not a replacement for proper water access. (extension.okstate.edu)

Should You Wet Feed or Soak Hay?

Adding water to a horse’s usual feed can deliver additional fluid and may be useful for older horses, poor drinkers or horses requiring soaked pellets, hay cubes or beet pulp.

However, wet feed should not be treated as proof that the horse is adequately hydrated. The horse must still have unrestricted access to drinking water, and actual bucket or trough intake should still be monitored.

Use the horse’s normal ration rather than suddenly introducing a large “winter mash.” Any wet feed should be prepared hygienically, fed promptly and discarded if it freezes, ferments or becomes spoiled. Some feeds, including beet pulp and certain cubes or pellets, must be prepared according to the manufacturer’s directions. (Merck Veterinary Manual)

Soaking hay may help with dust or dietary sugar management, but it is not the central answer to winter colic prevention. It can also alter nutrient content, create heavy frozen nets and become a hygiene problem if left sitting around.

Does Bran Mash Prevent Winter Colic?

No. Wheat bran is not a laxative.

The sudden appearance of softer manure after a bran mash is more likely to reflect an abrupt dietary change than a beneficial bowel-cleansing effect. Periodically feeding a large bran mash on cold nights may disturb the hindgut rather than protect it.

When bran is used, it should be incorporated consistently into a properly balanced ration rather than offered randomly as a once-a-week “colic prevention” treatment. (Merck Veterinary Manual)

The traditional Sunday bran mash has excellent branding. The evidence department was less impressed.

Increase Forage, Not Suddenly Grain

Horses often require more dietary energy during genuinely cold conditions, particularly if they are unclipped, wet, exposed to wind, underweight, young, old or without adequate shelter.

Forage is usually the best first source of additional winter energy because microbial fermentation of fibre produces heat. Increasing grain suddenly does not generate the same fermentation heat and can increase the risk of digestive disturbance. (University of Minnesota Extension)

That does not mean every horse needs unlimited hay or that grain is always inappropriate. Obese horses, ponies and horses with insulin dysregulation still require carefully controlled diets. The ration should match body condition, workload, forage quality and metabolic health.

Change Hay and Feed Gradually

A new hay delivery may look similar to the previous batch but can differ significantly in grass species, maturity, fibre, sugar, protein and digestibility.

Replace approximately 20% to 25% of the old feed with the new feed every other day, allowing at least a week for a complete transition. More sensitive horses may need longer. This gives the hindgut microbial population time to adapt. (University of Minnesota Extension)

Avoid making several changes at once, such as:

• Starting a new hay batch

• Increasing grain

• Adding beet pulp

• Introducing a new supplement

• Reducing turnout

• Moving stalls

When everything changes simultaneously, the gut objects and the detective work becomes fairly useless.

Why Hay Quality and Dental Care Matter

Coarse, stemmy or poorly digestible forage is harder to chew and process. This becomes more important in older horses, horses with missing teeth and horses with dental pain.

Poorly chewed fibres can increase the risk of obstruction, while dental discomfort may also reduce overall feed and water intake. Regular dental examinations and an appropriate alternative forage plan are especially important for senior horses during winter. (Today's Veterinary Practice)

Good-quality hay should be:

• Clean

• Free from visible mould

• Free from excessive dust

• Appropriate for the horse’s metabolic needs

• Palatable

• Chewable for that individual horse

“Green” is not automatically the same as nutritionally appropriate, and a very coarse hay is not transformed into good hay merely because the horse eventually manages to swallow it.

Keep Horses Moving Safely

Turnout is associated with a lower risk of colic, while recent stall confinement and reduced activity are recognised risk factors for impaction.

Movement supports normal gastrointestinal motility, maintains routine and usually gives horses more opportunities to drink and forage naturally. (Horse Report)

During winter:

• Maintain turnout when footing is safe

• Avoid unnecessary all-day stall confinement

• Hand-walk stalled horses if their veterinarian permits it

• Provide movement breaks during shows or travel

• Keep exercise changes gradual

• Do not turn a horse loose on dangerous ice merely for the sake of “gut movement”

For a horse on medical stall rest, the underlying injury takes priority. Discuss safe hand-walking or other movement with the treating veterinarian.

Which Horses Are at Greater Risk?

Extra monitoring is sensible for:

• Horses with a previous history of impaction

• Senior horses

• Horses with poor or missing teeth

• Horses on stall rest

• Horses that normally drink poorly

• Horses recently moved from pasture to hay

• Horses changing hay batches

• Horses eating coarse forage

• Horses with reduced manure production

• Horses after transport

• Horses with recent changes in exercise or routine

• Horses recovering from illness, anaesthesia or surgery

• Horses with known intestinal disease

• Young horses with significant parasite burdens

These horses may benefit from individually measured water, closer manure monitoring and a winter feeding plan established before temperatures fall. (Today's Veterinary Practice)

How Worried Should You Be?

Low Immediate Concern

The horse is:

• Bright and eating normally

• Drinking its usual amount

• Passing normal manure

• Comfortable

• Breathing normally

• Showing no abdominal pain

What to do: continue prevention, check water systems several times daily during freezing weather and monitor intake rather than assuming everything is fine.

Concerning

The horse has:

• Slightly reduced appetite

• Smaller or drier manure

• Reduced water intake

• Mild intermittent flank watching

• One brief episode of pawing

• A recent major change in hay, turnout or weather management

What to do: contact your veterinarian for guidance, stop exercise, measure vital signs if safe and monitor closely. Do not wait for dramatic rolling before taking the signs seriously.

Urgent

The horse has:

• Recurrent pawing or lying down

• Persistent flank watching

• Little or no manure

• Refusal to eat

• Increasing heart or respiratory rate

• Sweating

• Reduced or absent gut sounds

• Pain continuing beyond 15 to 30 minutes

• Pain that repeatedly returns

What to do: call your veterinarian urgently. Remove feed and prepare for an examination or referral.

Critical

The horse has:

• Violent or uncontrollable pain

• Repeated forceful rolling

• Collapse or weakness

• Marked abdominal distension

• Abnormal gum colour

• Persistent pain despite veterinary medication

• Rapid deterioration

• Signs of shock

• Inability to stand safely

What to do: this is an emergency. Arrange immediate veterinary care and prepare for transport to a referral hospital if advised.

These categories guide urgency only. They cannot identify the cause, and mild-looking signs can still occur with serious disease. (Horse Report)

Not Every Winter Colic Is an Impaction

Cold-weather abdominal pain can also be caused by:

• Gas or spasmodic colic

• Large-colon displacement

• Large-colon volvulus

• Small-intestinal obstruction

• Sand accumulation

• Enteroliths

• Parasite-associated disease

• Enteritis or colitis

• Gastric disease

• Ingestion of bedding or foreign material

• Grain overload

• Toxic plants

• Reproductive disease in mares

• Urinary disease

• Musculoskeletal pain that resembles colic

Impaction, gas and displacement are among the commonly encountered gastrointestinal causes, but owners cannot reliably distinguish them from behaviour alone. (Today's Veterinary Practice)

How Do Vets Diagnose Colic?

A colic assessment commonly includes:

• History of feed, water, manure and recent changes

• Temperature, heart rate and respiratory rate

• Gum colour and capillary refill time

• Abdominal auscultation

• Nasogastric intubation

• Rectal examination

• Blood testing

• Abdominal ultrasound

• Abdominal-fluid analysis in selected cases

• Radiographs in selected horses or facilities

These tests help determine whether the horse has a medical impaction, gas accumulation, displacement, inflammatory disease or a lesion that may require surgery. (Horse Report)

Impactions are commonly treated with pain relief, enteral fluids administered through a nasogastric tube, intravenous fluids and veterinarian-selected laxatives. Surgery may be required if the obstruction does not resolve or if the problem is actually a displacement, twist or other mechanical obstruction. (Today's Veterinary Practice)

What Should You Do Right Now if Your Horse Shows Colic Signs?

1. Call your veterinarian.
   Describe the signs, their duration, manure production, water intake and recent feeding or management changes.

2. Remove feed.
   Do not allow the horse to continue eating hay or grain until your veterinarian advises that feeding is safe.

3. Follow your veterinarian’s water instructions.
   UC Davis guidance recommends access to small amounts while waiting, but the recommendation may change depending on the horse’s condition.

4. Move the horse to a safe area.
   Prevent injury from fences, walls, feeders or icy footing.

5. Walk briefly only when safe.
   Gentle walking may support motility, but do not walk the horse to exhaustion. A quiet horse can be allowed to lie down if it is not thrashing.

6. Record vital signs if you can do so safely.
   Note heart rate, breathing rate, temperature, gum appearance and gut sounds.

7. Do not give medication unless directed.
   Pain relief may mask deterioration, and the drug or dose may be inappropriate.

8. Do not administer mineral oil, water or other fluids by mouth.
   Owners should never attempt to stomach-tube a horse. Incorrect administration can cause fatal aspiration.

9. Prepare transport.
   Have the trailer, referral-hospital details, insurance information and medical history ready.

10. Monitor the pattern.
    Note whether pain is continuous, intermittent, worsening or returning after treatment. (Horse Report)

Common Winter Colic Mistakes

Waiting Until the Horse Is Rolling Violently

Reduced appetite, dry manure and mild flank watching may be the early stage of a significant impaction.

Assuming a Cold Snap Directly Caused the Colic

The useful question is what changed with the weather: water access, hay, activity, feeding times or equipment.

Relying on Snow

Snow does not provide reliable or efficient hydration for a domestic horse eating dry forage.

Trusting an Automatic Waterer Without Checking It

Frozen pipes, mechanical failure, contamination or electrical current can stop a horse drinking.

Giving a Sudden Bran Mash

Bran is not a proven laxative, and abrupt diet changes can themselves upset the hindgut.

Increasing Grain Instead of Forage

Suddenly adding concentrate can increase digestive risk. Additional good-quality forage is usually the better first source of winter energy.

Forcing the Horse to Walk Continuously

Walking can be useful, but exhaustion helps nobody. A quiet horse may rest safely while waiting for the veterinarian.

Giving Electrolytes Without Adequate Water

Salt and electrolyte supplementation must always be accompanied by reliable access to plain water.

Changing Hay Overnight

The colour may look the same. The hindgut microbes may strongly disagree.

Winter Colic Prevention Checklist

Every Day

• Confirm every water source is flowing and unfrozen

• Measure or estimate actual intake

• Keep water around 45°F to 65°F where possible

• Check appetite and manure production

• Provide appropriate forage

• Maintain safe movement or turnout

• Provide access to plain salt

• Watch high-risk horses individually

Before a Freeze

• Test trough heaters and automatic waterers

• Inspect plugs, cables and grounding

• Prepare spare buckets and an alternative water supply

• Ensure enough familiar hay is available

• Avoid starting a new ration during the weather change

• Confirm your trailer and emergency plan are usable

Throughout Winter

• Introduce hay changes gradually

• Check body condition beneath the coat

• Maintain dental care

• Use parasite control based on veterinary guidance

• Review the plan for horses on stall rest

• Keep emergency veterinary numbers visible

• Know the route to the nearest referral hospital

Will a Horse With Winter Impaction Colic Be Okay?

Many uncomplicated large-colon impactions respond to medical treatment with fluids, pain management and laxatives.

The outlook is generally better when:

• Signs are recognised early

• The horse is examined promptly

• Hydration is corrected

• Pain is controllable

• The impaction begins to soften and move

• Manure production resumes

• No displacement, twist or intestinal damage is present

The outlook becomes more guarded when:

• Pain persists or worsens

• The horse develops marked abdominal distension

• Heart rate remains elevated

• Significant gastric reflux is present

• The intestine is displaced or twisted

• Treatment is delayed

• Surgery is required after intestinal damage has developed

The biggest danger is assuming every winter colic is “just a dry impaction.” A veterinary examination is what separates a medically manageable blockage from a time-critical surgical problem. (Today's Veterinary Practice)

FAQs About Winter Colic in Horses

Does cold weather itself cause colic?

Not necessarily. Evidence has not consistently shown a direct relationship between temperature change and colic. Cold weather can indirectly increase risk by reducing water intake, freezing water sources, changing forage and decreasing turnout. (Horse Report)

How much water should a horse drink during winter?

A typical 1,000-pound horse commonly needs at least 10 to 12 gallons, or approximately 38 to 45 litres, daily. Larger horses, lactating mares and working horses may require more. (University of Minnesota Extension)

What is the best water temperature for horses in winter?

Water between approximately 45°F and 65°F, or 7°C and 18°C, generally encourages good cold-weather intake. (ANSCI)

Does bran mash prevent impaction colic?

No. Wheat bran is not a laxative, and suddenly feeding a large mash may cause digestive upset. Wetting the horse’s normal, balanced ration is usually more sensible than introducing an occasional bran meal. (Merck Veterinary Manual)

Should you walk a horse with colic?

Brief walking can be helpful if it is safe, but the horse should not be walked to exhaustion. A quiet horse can be allowed to lie down, provided it is not thrashing or putting itself and handlers at risk. (Horse Report)

Final Thoughts

Winter colic prevention is less about defeating the cold and more about preventing the management changes that come with it.

The most important steps are:

• Keep water continuously available

• Offer water at a drinkable temperature

• Monitor what the horse actually consumes

• Prioritise consistent, good-quality forage

• Introduce diet changes gradually

• Maintain safe movement

• Pay extra attention to senior horses and poor drinkers

• Act early when appetite, manure or behaviour changes

A horse does not need to be violently rolling before colic becomes important. Small, dry manure and a half-finished bucket may be the first clues that the gut is heading in the wrong direction.

The best winter colic plan starts before the horse is looking at its flank.

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If your horse’s drinking, manure or behaviour changes during cold weather and you are unsure how urgent it is, ASK A VET™ can help you review the pattern and prepare the right information for your local veterinarian.