How to Feed a New Horse Without Causing Colic or Laminitis

By Dr Duncan Houston

Bringing a new horse home changes far more than their address.

Hay, concentrate, pasture, water, housing, exercise, feeding times and herd dynamics may all change within a few hours. That combination can place significant stress on the digestive system, even when every individual change seems harmless.

The safest approach is to preserve the horse’s previous diet initially, then introduce each new feed gradually while monitoring appetite, water intake, manure and hoof comfort.

Quick Answer

Ask the previous owner for enough of the horse’s current hay and concentrate to last at least 7 to 14 days. Replace only around 20% to 25% of the old feed every other day, extending the transition if the horse has a history of colic, laminitis, diarrhoea or metabolic disease.

Do not turn a newly arrived horse directly onto lush pasture or give a large grain meal after transport. Sudden changes in hay, concentrate, pasture, housing and water intake are all associated with increased colic risk. (University of Minnesota Extension)

Why Is Moving a Horse a Digestive Risk?

The move itself does not automatically cause colic. The real problem is that several recognised risk factors often happen simultaneously.

A newly arrived horse may experience:

• A different batch or type of hay

• A new concentrate

• Different feeding times

• Sudden pasture access

• Reduced water intake

• Long-distance transport

• Stall confinement

• Reduced movement

• Herd separation

• Social competition

• A completely different daily routine

A systematic review found that recent changes in feeding and housing were among the most consistently identified management-related colic risks. Changes in hay, concentrate and housing within the previous two weeks were repeatedly associated with increased risk. (PMC)

In one case-control study, a change in the batch of hay within the previous two weeks was associated with almost five times the odds of colic. This does not mean every hay change causes colic, but it shows why forage changes deserve the same care as grain changes. (PMC)

The practical rule is simple:

Do not change the horse’s hay, concentrate, pasture and management all at once unless circumstances make it unavoidable.

What Should You Ask Before the Horse Arrives?

Obtain a written feeding history rather than relying on “a scoop morning and night.”

Ask the previous owner or stable for:

• Exact hay type

• Approximate hay weight per day

• Whether hay was fed freely or in meals

• Brand and full name of concentrate

• Weight of concentrate per meal

• Number and timing of meals

• Pasture access and grass type

• Supplements and medications

• Salt and electrolyte use

• Water source

• Treats

• Recent feed changes

• Previous colic

• Previous laminitis

• Insulin dysregulation or EMS

• PPID

• Gastric ulcer history

• Choke history

• Dental problems

• Diarrhoea or abnormal manure

• Current body weight and condition

A scoop is not a meaningful measurement until the feed inside it has been weighed. Feed density varies considerably between grains, pellets and high-fibre products.

Request a photograph of the feed bag and feeding instructions. Ideally, obtain enough of the original hay and concentrate to cover the entire transition period.

Should a New Horse Be Quarantined?

A new horse should ideally be separated from resident horses for approximately two to three weeks, with dedicated buckets, equipment and feeding areas.

This supports biosecurity, but it also makes nutritional monitoring much easier. You can see exactly how much the horse eats, drinks and passes without wondering which horse emptied the bucket or produced the questionable manure pile. AAEP guidance recommends isolation of new arrivals and careful monitoring after transport. (extension.psu.edu)

Record the horse’s rectal temperature daily during the early arrival period. Fever, reduced appetite and diarrhoea should not automatically be blamed on a feed transition because infectious disease may present at the same time. (AAEP)

What Should You Feed During the First 24 Hours?

Provide Familiar Forage

Offer the horse the same hay they were eating before transport whenever possible.

Do not deliberately withhold forage for hours simply because the horse has arrived somewhere new. Familiar forage supports normal gut fill, chewing and routine.

Provide Clean Water Immediately

Offer clean water as soon as the horse is safely settled.

Monitor actual intake rather than merely checking that the bucket contains water. Reduced water intake and lack of water access have both been associated with increased colic risk. (PMC)

Some horses are suspicious of unfamiliar water. A clean bucket that allows intake to be measured is often more useful initially than relying only on an automatic waterer.

Avoid a Large Concentrate Meal

Do not greet a transported horse with a heroic bucket of grain.

Merck advises against grain-based meals larger than 0.25% of body weight within one hour of transport, strenuous exercise or another major stress. Exhausted horses with reduced gut motility should not receive a large concentrate meal. (Merck Veterinary Manual)

Once the horse is settled, drinking, passing manure and behaving normally, offer the usual familiar concentrate in its usual measured amount.

Do Not Introduce Lush Pasture Immediately

A horse may have lived outdoors previously and still be unadapted to the grass on your property.

Pasture species, maturity, fertilisation, climate and season can dramatically change its sugar and energy content. Start with controlled access rather than assuming that “grass is grass.”

Keep the First Day Boring

Unless urgently required, avoid introducing all of the following on arrival day:

• New concentrate

• New supplements

• Rich pasture

• Large quantities of treats

• High-intensity exercise

• Sudden group turnout

• Multiple nonessential procedures

Boring is underrated. The digestive tract generally prefers boring.

A Practical 10 to 14-Day Feed Transition

University of Minnesota guidance recommends replacing only around 20% to 25% of the horse’s current feed every other day. This gives the hindgut microbial population time to adapt. (University of Minnesota Extension)

Transition period	Old feed	New feed
Days 1 to 2	75% to 80%	20% to 25%
Days 3 to 4	50% to 60%	40% to 50%
Days 5 to 6	25% to 40%	60% to 75%
Days 7 to 10	0% to 20%	80% to 100%
Days 10 to 14	0%	100%

This is a practical framework, not a race.

Extend the transition when the horse:

• Has previously had colic

• Has loose manure

• Is elderly

• Has poor dentition

• Has recently travelled a long distance

• Is underweight

• Has EMS or PPID

• Has a laminitis history

• Is moving from dry forage to lush pasture

• Is changing several parts of the ration

If manure softens or appetite declines, stop increasing the new feed. Hold at the current ratio or return to the previous well-tolerated stage while monitoring the horse.

Persistent deterioration needs veterinary assessment rather than an endlessly revised feed spreadsheet.

Change One Major Part of the Diet at a Time

Where practical:

1. Stabilise the horse on familiar hay and concentrate.

2. Transition the hay.

3. Allow appetite and manure to remain normal for several days.

4. Transition the concentrate if it genuinely needs changing.

5. Introduce pasture separately.

6. Add only necessary supplements after the base ration is stable.

This method makes it much easier to identify which change caused a problem.

Changing hay, grain, supplements and pasture together creates a nutritional detective story with far too many suspects.

Hay Changes Matter Just as Much as Grain Changes

Owners often concentrate on changing the bagged feed slowly while replacing the horse’s entire forage ration overnight.

Hay batches can differ in:

• Grass species

• Maturity

• Leaf-to-stem ratio

• Fibre

• Protein

• Digestible energy

• Sugar and starch

• Mineral content

• Dust

• Mould contamination

Even two batches sold under the same name can be nutritionally different.

Recent changes in hay type or batch have repeatedly been associated with increased colic risk. Introduce new hay by weight, mixing it with the familiar hay over at least one week and preferably 10 to 14 days in sensitive horses. (University of Minnesota Extension)

All hay should be:

• Clean

• Properly cured

• Free from visible mould

• Free from musty odour

• Free from toxic plants

• Appropriate for the horse’s metabolic health

• Suitable for the horse’s teeth

Horses are particularly sensitive to spoiled feed, and mouldy roughage should not be used simply because the horse is new and “probably ate worse before.” (Merck Veterinary Manual)

How Much Forage Should a New Horse Receive?

Most healthy horses should receive at least approximately 1.5% of their body weight in forage or other high-fibre dry matter per day. Many horses maintain better body condition and digestive health closer to 2%, depending on workload, metabolic health and forage quality. (Merck Veterinary Manual)

For a 500-kilogram horse:

• 1.5% equals 7.5 kilograms of dry matter

• 2% equals 10 kilograms of dry matter

Hay is usually not 100% dry matter, so the actual weight placed in the hay net will be slightly greater.

The correct amount depends on:

• Current body condition

• Target body condition

• Workload

• Pasture intake

• Hay analysis

• Age

• Dental function

• Pregnancy or lactation

• Metabolic disease

Do not slash forage simply because the horse is overweight. Severe feed restriction can create additional welfare and metabolic problems. Weight-loss plans should be measured and monitored. (Merck Veterinary Manual)

Does a New Horse Need Concentrate?

Not necessarily.

Many adult horses at maintenance or in light work can meet their energy requirements through appropriate forage plus salt and, where needed, a ration balancer.

Concentrate may be appropriate when the horse:

• Performs significant work

• Cannot maintain weight on suitable forage

• Is growing

• Is pregnant or lactating

• Has poor teeth

• Needs a complete senior feed

• Requires a therapeutic ration

• Has a demonstrated protein, vitamin or mineral gap

Do not automatically start grain because the horse appears thin.

Weight loss may result from:

• Dental disease

• Poor-quality forage

• Inadequate access to feed

• Parasites

• PPID

• Gastric disease

• Chronic pain

• Intestinal disease

• Liver or kidney disease

• Social competition

• Excessive workload

The mistake I see most often is treating “thin” as the diagnosis.

How Large Can a Concentrate Meal Be?

A horse should not receive more than 0.5% of body weight in grain-based concentrate at one feeding.

For a 500-kilogram horse, this is an upper limit of approximately 2.5 kilograms per meal. Smaller portions are generally preferable, especially during a transition. Larger daily amounts should be divided into several meals at least four hours apart. (Merck Veterinary Manual)

This is an upper ceiling, not a target.

A new horse receiving an unfamiliar feed should begin with a substantially smaller amount and increase only if the ration assessment shows that additional concentrate is necessary.

Feed concentrate by weight, not by volume.

Why Can Sudden Grain Changes Cause Problems?

The small intestine has limited capacity to digest starch.

When a large starch meal is fed, some starch may reach the caecum and colon. Rapid fermentation alters the microbial population, increases acid production and lowers hindgut pH.

This may contribute to:

• Gas production

• Abdominal pain

• Loose manure

• Hindgut acidosis

• Colitis

• Endotoxaemia

• Laminitis

High concentrate intake and recent feed changes have repeatedly been associated with increased colic risk. (Merck Veterinary Manual)

The solution is not a supplement sprinkled over an oversized grain meal.

The solution is to keep the meal appropriately small, introduce it gradually and use forage, digestible fibre or fat when safer calorie sources are needed.

How Should Pasture Be Introduced?

A new horse should be treated as pasture-naive unless their recent grazing history is known.

University guidance recommends beginning with around 15 minutes of grazing and increasing access by approximately 15 minutes per day. Reaching five hours of grazing may therefore take several weeks. (University of Minnesota Extension)

A practical schedule is:

Day	Grazing time
1	15 minutes
2	30 minutes
3	45 minutes
4	60 minutes
5 onward	Increase by around 15 minutes daily

This schedule may need to be slower when:

• The grass is lush and rapidly growing

• The horse has been eating only dry hay

• The horse is a pony or easy keeper

• The horse is overweight

• There is previous laminitis

• Insulin status is unknown

• The pasture contains cool-season grasses

• Weather conditions have increased grass sugar

• The horse is arriving during spring or autumn growth

Feeding familiar hay before turnout may reduce the urge to gorge, but it does not make rich pasture safe for an insulin-dysregulated horse.

Why Can New Pasture Cause Laminitis?

Laminitis, often called founder, involves damage and weakening of the tissues suspending the coffin bone inside the hoof.

Rapid access to carbohydrate-rich pasture can create a significant insulin response in susceptible horses. Ponies, easy keepers, horses with EMS and some horses with PPID may develop hyperinsulinaemia severe enough to trigger laminitis. (extension.okstate.edu)

Signs include:

• Hot feet

• Strong or bounding digital pulses

• Short, stiff steps

• Reluctance to turn

• Shifting weight

• Increased lying down

• Refusal to walk

• A rocked-back stance

Do not wait for the classic rocked-back posture. Early laminitis may first look like mild foot soreness or reluctance to turn.

A horse with previous laminitis, obesity or a cresty neck should not be given unrestricted pasture until metabolic risk has been assessed.

Why Water Monitoring Matters

Water intake often changes after transport.

The horse may:

• Dislike unfamiliar water

• Fail to understand a new automatic drinker

• Be too stressed to drink normally

• Lose access because of dominant horses

• Drink less after moving from pasture to dry hay

• Drink less in cold weather

Decreased water intake and absent water access have both been associated with higher colic risk. (PMC)

During the first week:

• Use a bucket or water meter where intake can be estimated.

• Check automatic waterers manually.

• Clean containers daily.

• Provide more than one source if practical.

• Confirm the horse can access water without competition.

• Watch urine output and manure moisture.

Adding water to familiar feed may provide additional fluid, but it does not replace unrestricted drinking water.

Should New Horses Receive Small, Frequent Meals?

Forage should be available frequently and long fasting periods should be avoided.

Concentrate is different. If it is needed, divide the total daily amount into smaller measured meals rather than serving one or two oversized buckets. Meals containing substantial grain should be spaced at least four hours apart. (Merck Veterinary Manual)

Slow feeders can help extend forage intake, but they must be safe and appropriate for the horse.

Check that:

• Openings are not excessively small

• Shoes cannot become trapped

• The horse can still consume enough forage

• The feeder does not cause frustration or damage teeth

• More than one station is available in group housing

The goal is longer, calmer forage intake, not forcing the horse to fight a net for every mouthful.

Do Probiotics Prevent Digestive Upset During a Move?

Do not rely on a probiotic to make rapid diet changes safe.

Some products may affect microbial populations or manure consistency, but equine products vary widely, and evidence for routine clinical benefit remains inconsistent. Merck notes that the ideal probiotic supplementation strategy for horses is still undetermined. (Merck Veterinary Manual)

A supplement cannot compensate for:

• An abrupt hay change

• A large grain meal

• Dehydration

• Lush pasture exposure

• Poor dental function

• Infectious diarrhoea

• Parasite disease

• Surgical colic

Establish the forage, water and feeding schedule first. Add only supplements that have a clear purpose.

What if the New Horse Is Very Thin?

Do not suddenly provide unlimited grain or a rich conditioning ration.

A severely underweight or starved horse is at risk of refeeding syndrome, which can cause life-threatening electrolyte and organ dysfunction. These horses require veterinary assessment and a controlled feeding protocol using small, frequent meals. (Merck Veterinary Manual)

For a horse that is only mildly underweight:

1. Confirm actual weight and body condition.

2. Arrange a dental examination.

3. Review parasite history.

4. Assess forage quality and intake.

5. Check for chronic disease.

6. Increase calories gradually.

7. Monitor weight every one to two weeks.

Healthy weight gain should take weeks to months, not a weekend and half the feed room. (Merck Veterinary Manual)

How Worried Should You Be?

Low Risk

The horse:

• Is bright and eating normally

• Drinks well

• Passes normal manure

• Has no colic or laminitis history

• Is receiving familiar forage

• Is transitioning gradually

• Has no sudden pasture access

What to do: continue the planned transition and record appetite, water and manure each day.

Moderate Risk

The horse has:

• Slightly softer manure

• Mild reduction in water intake

• Slower eating

• A recent unavoidable hay change

• Mild stress after transport

• No fever, pain or foot soreness

What to do: pause the transition. Do not increase the new feed for 24 to 48 hours. Maintain familiar forage, monitor temperature and contact your veterinarian if the horse fails to return to normal promptly.

High Risk

The horse has:

• Reduced appetite

• Recurrent soft manure or diarrhoea

• Fewer or smaller manure piles

• Intermittent flank watching

• Repeated pawing

• Increased hoof heat

• Strong digital pulses

• A history of colic or laminitis

• Sudden access to grain or pasture

What to do: stop further dietary changes and contact your veterinarian the same day.

Critical

The horse has:

• Repeated rolling

• Severe or persistent abdominal pain

• Marked abdominal distension

• Profuse watery diarrhoea

• Feed or saliva from the nostrils

• Inability to swallow

• Severe foot pain

• Weakness or collapse

• Rapid deterioration

What to do: seek emergency veterinary care immediately.

When Is This an Emergency?

Colic

Call urgently if the horse has:

• Repeated pawing

• Persistent flank watching

• Repeated lying down or rolling

• Sweating without exercise

• Refusal to eat

• Little or no manure

• Abdominal enlargement

• Pain that worsens over a few hours

• Pain that returns after medication

• Weakness or collapse

Do not give another feed or mash to “get the gut moving.” Do not administer medication or mineral oil unless directed by the veterinarian.

Grain Overload

Treat unrestricted access to a feed room, grain bin or concentrate bag as an emergency even if the horse still looks normal.

Remove access, estimate the amount eaten, save the feed label and call your veterinarian immediately. Digestive and hoof complications can develop after the horse initially appears comfortable.

Laminitis

Call immediately if the horse develops:

• Hot feet

• Bounding digital pulses

• Short, pottery steps

• Reluctance to turn

• Weight shifting

• Rocking back onto the hindlimbs

• Refusal to move

Laminitis can progress to rotation or sinking of the coffin bone. Early treatment matters. (Merck Veterinary Manual)

Choke

Feed or saliva coming from the nostrils, repeated coughing, neck stretching and inability to swallow suggest oesophageal obstruction.

Remove all food and water and call your veterinarian. Do not pour oil or water into the mouth. (Merck Veterinary Manual)

Severe Diarrhoea

Profuse watery diarrhoea, especially with fever, depression or reduced appetite, is an emergency and may be infectious.

Adult horses can lose large quantities of fluid rapidly. Isolate the horse from others and contact your veterinarian. (Merck Veterinary Manual)

What Else Can Cause Digestive Signs After a Move?

Not every problem following a feed change is caused by the feed.

Important alternatives include:

• Transport stress

• Infectious diarrhoea

• Equine coronavirus

• Salmonellosis

• Parasite disease

• Sand ingestion

• Gastric ulcers

• Dental disease

• Choke

• Poor water intake

• Toxin exposure

• NSAID-associated colitis

• A surgical intestinal obstruction

• Social stress and feed competition

A new horse with fever, diarrhoea or respiratory signs should be treated as a possible infectious-disease case rather than simply being placed on a new gut supplement. AAEP guidelines list recent travel, feed changes and other illnesses on the property among the key history points in horses with acute diarrhoea. (AAEP)

What Should You Do if Appetite or Manure Changes?

If the Horse Is Bright With Mildly Soft Manure

• Pause the feed transition.

• Stay at the last well-tolerated ratio.

• Check temperature.

• Confirm water intake.

• Remove unnecessary treats and supplements.

• Monitor manure over the next 12 to 24 hours.

• Call your veterinarian if the change persists, recurs or worsens.

If the Horse Stops Eating

Do not assume stress is the only cause.

Check for:

• Colic

• Fever

• Choke

• Dental pain

• Respiratory illness

• Foot pain

• Diarrhoea

• Abnormal manure production

A marked or persistent appetite reduction after transport warrants veterinary advice.

If the Horse Shows Colic

• Remove feed.

• Place the horse in a safe area.

• Call your veterinarian.

• Record heart rate, temperature and gum colour if safe.

• Do not walk the horse to exhaustion.

• Do not give oral remedies unless directed.

• Prepare for referral if advised.

If the Feet Become Sore

• Stop pasture and concentrate access.

• Keep movement to a minimum.

• Place the horse on deep, soft footing.

• Call your veterinarian.

• Do not force the horse to walk.

• Arrange farriery support as directed.

Common Mistakes When Feeding a New Horse

Changing to a “Better” Feed Immediately

A nutritionally superior product can still cause trouble when introduced abruptly.

Forgetting That Hay Is a Feed Change

A different cutting, batch or species of hay can alter fibre, calories and fermentation.

Turning the Horse Straight Onto Grass

A horse that lived outside may still be unadapted to your pasture.

Feeding a Large Meal After Transport

Stress, fatigue, reduced water intake and poor gut motility make this an especially poor time for a large grain meal.

Feeding by Scoop

Different feeds can vary enormously in weight and energy per scoop.

Trying to Fatten a Thin Horse Quickly

Thin horses need investigation and gradual nutritional rehabilitation, not uncontrolled grain.

Adding Several Supplements at Once

This increases cost, complicates the ration and makes adverse reactions harder to identify.

Ignoring Water Intake

A full trough does not prove that the horse is drinking.

Assuming Soft Manure Is Just Stress

Mild transient softening can occur, but fever, profuse diarrhoea, depression or continued deterioration require veterinary assessment.

How Can Colic and Laminitis Risk Be Reduced?

• Obtain the previous feeding history.

• Bring familiar hay and concentrate.

• Transition feeds over at least 7 to 14 days.

• Replace no more than 20% to 25% every other day.

• Change one major feed component at a time.

• Keep forage as the foundation.

• Weigh hay and concentrate.

• Keep grain meals well below 0.5% of body weight.

• Avoid large concentrate meals after transport.

• Introduce pasture in 15-minute increments.

• Restrict pasture in metabolically at-risk horses.

• Provide continuous clean water.

• Monitor actual drinking.

• Use separate feeding stations.

• Maintain consistent feeding times.

• Watch appetite and manure twice daily.

• Check digital pulses during pasture introduction.

• Investigate dental disease and unexplained weight loss.

• Secure all feed rooms and grain bins.

The safest transition is not the fastest one the horse appears to tolerate.

It is the slowest practical transition that keeps the horse eating, drinking, passing normal manure and remaining comfortable.

New Horse Feeding Checklist

Before Arrival

• Obtain the exact feeding history.

• Purchase or collect old hay and feed.

• Weigh the previous scoop.

• Prepare separate buckets and equipment.

• Inspect quarantine housing.

• Check fencing, water and pasture.

• Arrange a veterinary examination.

Arrival Day

• Offer familiar forage.

• Offer clean water.

• Avoid a large concentrate meal.

• Keep the horse separate.

• Record temperature.

• Monitor manure and urine.

• Do not turn onto lush pasture.

First Week

• Begin the gradual feed transition.

• Weigh every ration.

• Monitor appetite twice daily.

• Record manure changes.

• Check water intake.

• Introduce pasture cautiously.

• Avoid unnecessary supplements.

Second Week

• Complete the transition only if the horse remains normal.

• Reassess body weight and condition.

• Review concentrate need.

• Confirm dental and parasite plans.

• Adjust exercise gradually.

• Continue monitoring for laminitis and digestive signs.

FAQs About Feeding a New Horse

How long should a horse feed transition take?

Allow at least 7 to 14 days. Replace approximately 20% to 25% of the old feed every other day. Sensitive horses may need a slower transition. (University of Minnesota Extension)

Can I change hay immediately if it is the same type?

It is better not to. Different batches of the same hay type can vary considerably, and recent hay-batch changes have been associated with increased colic risk.

How quickly can a new horse go onto pasture?

Start with approximately 15 minutes and increase by around 15 minutes per day. Use a slower or more restrictive plan for ponies, easy keepers and horses with metabolic or laminitis risk. (University of Minnesota Extension)

My new horse is thin. Should I start more grain immediately?

No. First investigate forage intake, dental health, parasites, PPID, ulcers, pain and other disease. Increase calories gradually once the reason for poor condition is understood.

How soon after transport can a horse eat?

Familiar forage and water can usually be offered once the horse is safely settled. Avoid a large grain-based meal within the first hour after transport or while the horse is exhausted or not drinking normally. (Merck Veterinary Manual)

Final Thoughts

The digestive system does not know that you bought better hay, a more expensive feed or access to a beautiful pasture.

It only knows that the diet changed.

When a horse moves properties, the safest plan is to protect continuity first and improve the ration second.

Bring familiar forage. Measure the existing feed. Monitor water. Transition each component gradually. Introduce pasture in minutes rather than hours. Watch manure, appetite and digital pulses closely during the first two weeks.

Most new horses settle without digestive problems when the transition is deliberate.

The danger comes from enthusiasm: new feed, new field, new supplements and a large welcome dinner all arriving before the hindgut has unpacked its bags.

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ASK A VET™ can help you organise your new horse’s previous diet, body condition, pasture exposure and transition schedule while your local veterinarian assesses any colic, diarrhoea, laminitis or weight-loss concerns.