Palmar Foot Pain in Horses: Signs, Diagnosis and Shoeing

By Dr Duncan Houston

Palmar foot pain is one of the most common and frustrating causes of front limb lameness in horses.

Owners often hear the word “navicular” and immediately think the navicular bone is the whole problem. Sometimes it is. But very often, the pain comes from a combination of structures in the back of the foot: the navicular bone, navicular bursa, deep digital flexor tendon, collateral sesamoidean ligaments, distal impar ligament, coffin joint, heel structures, frog, sole, digital cushion, and hoof capsule.

That is why modern vets are more careful with language. A horse that blocks to the back of the foot has palmar foot pain. The next job is finding which structure is actually painful.

The wrong shoe, wedge, injection, or drug can make the horse look better for a while while the real problem keeps ticking away quietly in the hoof. Sneaky little hoof gremlin.

Quick Answer

Palmar foot pain means pain coming from the back part of the horse’s foot, often involving the navicular apparatus, deep digital flexor tendon, navicular bursa, ligaments, coffin joint region, heel structures, or hoof balance. It commonly causes short, choppy front limb movement, worse lameness on hard ground or circles, heel sensitivity, stumbling, toe-first landing, or reduced performance. Diagnosis usually requires a lameness exam, diagnostic nerve blocks, radiographs, farrier assessment, and sometimes MRI because radiographs only show bone, not the deep soft tissue structures inside the hoof capsule. (Merck Veterinary Manual)

What Is Palmar Foot Pain?

Palmar foot pain is pain from the back half of the front hoof.

It may involve one structure or several structures at the same time. This is why the older phrase “navicular disease” can be misleading. Merck Veterinary Manual describes navicular syndrome as a degenerative disease complex that can involve the navicular bone, navicular bursa, collateral sesamoid ligaments, distal impar ligament, or deep digital flexor tendon. (Merck Veterinary Manual)

The University of Illinois explains it similarly: navicular disease, navicular syndrome, and caudal heel pain are often used for the same broad problem, but “syndrome” is more accurate because the condition varies between horses and may involve multiple structures. (Veterinary Medicine at Illinois)

So the correct first question is not:

“Does my horse have navicular?”

The better question is:

Which part of the palmar foot is causing the pain?

That answer changes the treatment.

Why “Navicular Disease” Is Too Simple

For years, horses with chronic heel pain were often diagnosed from radiographs alone. If the navicular bone looked abnormal, the horse was labelled with navicular disease.

The problem is that radiographs only show bone.

They do not properly show the deep digital flexor tendon, navicular bursa, distal impar ligament, collateral sesamoidean ligaments, or other soft tissue structures inside the hoof capsule. University of Illinois notes that MRI is considered the gold standard for diagnosing navicular syndrome because it is the only imaging option that thoroughly evaluates both bony and soft tissue structures within the hoof. (Veterinary Medicine at Illinois)

This matters because two horses can both block to the heel region and look similar on the lunge, but have completely different problems:

Horse	Main pain source	Best treatment direction
Horse A	Navicular bone remodelling	Bone-focused treatment, farriery, medication, workload management
Horse B	Deep digital flexor tendon tear	Soft tissue rehabilitation, MRI-guided plan, careful return to work
Horse C	Coffin joint inflammation	Joint-directed treatment and hoof balance
Horse D	Crushed heels and poor breakover	Farrier-led hoof rehabilitation
Horse E	Navicular bursa pain	Bursa-focused treatment, possible advanced imaging or referral

That is why one horse improves with one shoe, while another horse gets worse in the exact same shoe.

The shoe was not magic.

The diagnosis was different.

What Structures Are in the Palmar Foot?

The palmar foot includes several important structures:

• Navicular bone

• Navicular bursa

• Deep digital flexor tendon

• Collateral sesamoidean ligaments

• Distal impar ligament

• Coffin joint region

• Digital cushion

• Frog

• Heel bulbs

• Sole

• Hoof wall and bars

• Laminae and white line

• Palmar hoof capsule

The navicular bone acts as a smooth surface over which the deep digital flexor tendon passes before attaching to the coffin bone. Utah State University describes the navicular bone as helping provide a constant angle of insertion for the deep digital flexor tendon, with considerable forces applied when the foot is weight-bearing. (Utah State University Extension)

When hoof balance, workload, conformation, or internal injury increases stress in this area, pain can develop.

Signs of Palmar Foot Pain in Horses

Palmar foot pain may be subtle at first.

Common signs include:

• Short, choppy front limb stride

• Stumbling or tripping

• Toe-first landing

• Reluctance to land heel first

• Worse lameness on hard ground

• Worse lameness on circles

• Reluctance to turn tightly

• Pointing one front foot

• Shorter stride downhill

• Poor performance

• Loss of impulsion

• Sensitivity over the heel or frog with hoof testers

• Improvement after a palmar digital nerve block

• One front limb looking worse, even though both feet may be involved

Merck notes that navicular syndrome is commonly a bilateral forelimb lameness, although one limb often appears worse than the other. Horses may show shortened stride, shuffling gait, overt lameness, or stumbling, and many show heel or frog sensitivity with hoof testers. (Merck Veterinary Manual)

In practice, owners often say:

“My horse feels like they are landing carefully.”

That is a big clue.

Why Horses With Palmar Foot Pain May Look Like They Have Shoulder Pain

A lot of horses with heel pain are described as “short in the shoulder.”

That makes sense visually, because the horse shortens the whole front stride to reduce loading through the painful back of the foot. Merck notes that owners commonly think navicular-type lameness originates from the shoulder. (Merck Veterinary Manual)

The shoulder is often innocent.

The foot is just very good at framing it.

Which Horses Are Most at Risk?

Palmar foot pain can affect many horses, but risk is higher in certain types.

Merck lists American Quarter Horses, Thoroughbreds, and Warmbloods as commonly affected breeds, and notes that horses with small hooves, larger bodies, narrow upright feet, contracted heels, small frogs, long toes, low heels, hoof imbalance, poor hoof management, or inappropriate shoeing are predisposed. (Merck Veterinary Manual)

Risk factors include:

• Long toes

• Low or underrun heels

• Small feet relative to body size

• Contracted heels

• Narrow frogs

• Thin soles

• Broken-back hoof-pastern axis

• Poor breakover

• Sheared heels

• Medial-to-lateral imbalance

• Poor shoe fit

• Repetitive concussion

• Hard ground

• Disciplines with tight turns or repeated loading

• Previous heel pain or hoof imbalance

Commonly affected groups include:

• Quarter Horses

• Thoroughbreds

• Warmbloods

• Barrel horses

• Jumpers

• Eventers

• Ranch horses

• Dressage horses

• Horses with long-toe, low-heel conformation

• Large horses with relatively small feet

Breed matters, but hoof mechanics matter more.

Why Long Toes and Low Heels Matter

Long toes and low heels increase mechanical strain through the back of the foot.

A long toe delays breakover, meaning the foot stays loaded longer before leaving the ground. A low or underrun heel can concentrate stress in the palmar foot and increase deep digital flexor tendon strain. Utah State University notes that low underrun heels and long toes increase load on the deep digital flexor tendon, and that hoof angle changes can influence force through the navicular region. (Utah State University Extension)

Dr Stephen O’Grady’s equine podiatry discussion explains that low hoof angle and long-toe, low-heel conformation can increase strain on the deep digital flexor tendon and stress on the navicular apparatus and other palmar foot structures. It also emphasises that farriery should redistribute load across the bottom of the foot and improve breakover rather than simply make the hoof look taller. (Equipodiatry)

That is the clinical point:

Palmar foot pain is often not just a disease inside the hoof. It is also a loading problem.

Are Heel Wedges Good or Bad?

Heel wedges can help some horses.

They can reduce tension on the deep digital flexor tendon and change forces through the navicular region. Utah State University describes heel elevation and rolled breakover as common recommendations in navicular cases, especially where hoof-pastern alignment needs improvement. (Utah State University Extension)

But wedges are not harmless.

A wedge may temporarily make a horse more comfortable while worsening the underlying heel problem if it is used without a long-term plan. This is especially true in horses with crushed, weak, underrun, or poorly developed heels.

O’Grady’s podiatry discussion is very useful here. It explains that low or underrun heel treatment is difficult, and that the ability to improve palmar soft tissue structures and generate new heel growth may be limited when the digital cushion, frog apparatus, and ungual cartilages are compromised. It also stresses that shoeing must load-share across the palmar foot and be based on the structures present, not just place more load on weak heels. (Equipodiatry)

So the answer is not “wedges are good” or “wedges are bad.”

The answer is:

Wedges can be useful short-term tools in selected horses, but they should not replace a hoof rehabilitation plan.

What Smart Shoeing Should Aim To Do

Good shoeing for palmar foot pain should be built around the horse’s diagnosis and hoof capsule.

The goals may include:

• Shorten or ease breakover

• Improve hoof-pastern alignment

• Reduce excessive deep digital flexor tendon strain

• Support the palmar foot

• Improve heel loading where possible

• Protect thin soles

• Reduce focal pressure

• Encourage a more comfortable landing

• Avoid crushing already weak heels

• Match shoeing to the horse’s job and surface

Merck lists rolling or rockering the toe, or setting the shoe more palmarly to reduce breakover distance, as common first-line shoeing changes in navicular syndrome. (Merck Veterinary Manual)

Options may include:

• Rolled toe

• Rockered toe

• Shorter breakover

• Wider web shoes

• Bar shoes

• Straight bar shoes

• Egg bar shoes in selected cases

• Pads or pour-in support

• Frog support where tolerated

• Heel support

• Wedges in selected short-term cases

• Hoof boots for some barefoot transitions

• Shorter shoeing cycles

• Radiograph-guided trimming

The exact shoe depends on the horse. The fact that one horse improved in a particular shoe does not mean your horse needs the same one.

Why One Shoe Does Not Fit Every Navicular Horse

University of Illinois makes this point beautifully: some owners request a shoe because it helped another horse, but that other horse may have had different soft tissue injuries, different conformation, and a different job. Treatment should be selected based on the injuries identified, the horse’s use, and the horse’s conformation. (Veterinary Medicine at Illinois)

That is the difference between farriery and guessing.

A barrel horse, dressage horse, western pleasure horse, jumper, retired pasture horse, and racehorse may all need different mechanical solutions.

The best farrier plan usually comes from three things working together:

• Lameness localisation

• Imaging

• Vet-farrier communication

Not vibes. Not Facebook. Not “this worked on my mate’s horse.”

How Worried Should You Be?

Low Concern

This is more likely when:

• The horse is only slightly short-strided.

• The horse is sound at walk.

• There is no digital pulse increase.

• There is no sudden severe lameness.

• The horse is mildly worse on hard ground but improves with rest.

• Hoof balance issues are mild and manageable.

Action: reduce hard work, check hoof balance, avoid hard or rocky surfaces, and arrange a vet-farrier review if signs persist beyond a few rides.

Moderate Concern

This is more likely when:

• Lameness is visible at trot.

• The horse is short and choppy in front.

• The horse is worse on circles.

• Hoof testers cause heel or frog pain.

• The horse is landing toe first.

• Long toes, low heels, or crushed heels are present.

• Performance is declining.

Action: book a veterinary lameness exam. The horse may need diagnostic blocks, radiographs, and a farrier plan based on imaging.

High Concern

This is more likely when:

• The horse is repeatedly lame.

• Lameness improves with palmar digital nerve blocks.

• Radiographs show navicular bone changes.

• MRI shows deep digital flexor tendon, bursa, ligament, or navicular bone lesions.

• The horse has chronic crushed heels or poor hoof capsule distortion.

• The horse relapses when work increases.

• Previous shoeing changes have failed.

Action: a full treatment plan is needed. This may involve MRI, therapeutic farriery, injections, medication, rest, workload change, or referral-level care.

Critical

Treat this as urgent if:

• The horse is suddenly severely lame.

• The horse is non-weight-bearing.

• There is a hot hoof and strong digital pulse.

• Laminitis is possible.

• A hoof abscess is possible.

• A puncture wound is present.

• The horse has swelling extending above the hoof.

• The horse cannot turn or walk comfortably.

Action: call your vet promptly. Sudden severe foot pain is not a routine palmar foot pain management issue.

When Is Palmar Foot Pain an Emergency?

Chronic palmar foot pain is usually not a same-hour emergency, but some causes of foot pain are urgent.

Call your vet urgently if your horse has:

• Sudden severe lameness

• Non-weight-bearing lameness

• Strong digital pulse

• Hot painful hoof

• Reluctance to move

• Pain in more than one foot

• Rocked-back stance

• A nail, screw, wire, or sharp object in the foot

• A draining tract with severe pain

• Swelling above the hoof

• Fever or depression

• Severe worsening after shoeing

Do not assume sudden heel pain is navicular. Hoof abscess, laminitis, puncture wound, fracture, or deep infection may look similar early.

If the horse is suddenly very lame, treat the foot as urgent until proven otherwise.

How Vets Diagnose Palmar Foot Pain

A good diagnosis is stepwise.

1. History

Your vet will ask:

• How long has the horse been lame?

• Is one foot worse than the other?

• Is lameness worse on hard ground?

• Is it worse on circles?

• Is it worse after shoeing?

• Does the horse stumble?

• Does the horse land toe first?

• Has hoof balance changed?

• Has workload or footing changed?

• What treatments have already been tried?

A clinical evaluation article from AAEP proceedings emphasises that history, exercise schedule, duration of lameness, shoeing changes, surfaces, previous diagnostics, and treatment response are critical in palmar foot pain cases. (Equipodiatry)

2. Hoof and Limb Examination

The vet will assess:

• Hoof shape

• Toe length

• Heel height

• Frog size

• Digital cushion development

• Sole depth

• White line

• Heel contraction

• Sheared heels

• Hoof-pastern axis

• Digital pulses

• Hoof tester response

• Landing pattern

• Limb conformation

3. Gait Assessment

The horse may be assessed:

• At walk

• At trot

• On hard ground

• On soft ground

• On circles

• On straight lines

• Under saddle if signs are subtle or performance-related

4. Diagnostic Nerve Blocks

Palmar digital nerve blocks are commonly used to localise pain to the back of the foot.

Merck notes that many horses with navicular syndrome show marked improvement after a palmar digital nerve block, and lameness in the opposite limb may then become apparent because the disease is often bilateral. (Merck Veterinary Manual)

But a nerve block does not tell you which structure is painful. It tells you the region.

That is why imaging matters.

5. Radiographs

Radiographs assess:

• Navicular bone shape

• Vascular channels

• Sclerosis

• Flexor cortex changes

• Distal border fragments

• Cyst-like lesions

• Coffin bone alignment

• Sole depth

• Palmar angle

• Hoof balance

Radiographs are essential, but they have limits. Merck notes that horses without notable radiographic changes may still have soft tissue injuries associated with the navicular apparatus. (Merck Veterinary Manual)

6. MRI

MRI is the most useful tool when the diagnosis remains unclear or soft tissue injury is suspected.

MRI can identify:

• Deep digital flexor tendon tears

• Navicular bone oedema or sclerosis

• Navicular bursa pathology

• Distal impar ligament injury

• Collateral sesamoidean ligament injury

• Coffin joint changes

• Bone and soft tissue involvement together

Merck states that MRI delineates lesions within all structures of the podotrochlear apparatus and provides a comprehensive definition of each case. (Merck Veterinary Manual)

What Else Can Look Like Palmar Foot Pain?

Many problems can mimic palmar foot pain.

Important rule-outs include:

Hoof Abscess

Often sudden and severe. May cause strong digital pulse, heat, and marked lameness.

Laminitis

Can cause bilateral foot pain, strong pulses, heat, reluctance to move, and abnormal stance.

Coffin Joint Pain

May block similarly and can overlap with heel pain.

Deep Digital Flexor Tendon Injury

Often invisible on radiographs and may require MRI.

Navicular Bursa Pain

May require bursal imaging or targeted treatment.

Distal Impar Ligament Injury

Can cause pain close to the navicular bone and coffin bone.

Thin Soles or Bruising

Often worse on hard or rocky ground.

White Line Disease

Can cause hoof instability, cracks, abscesses, and chronic pain.

Poor Hoof Balance

Long toes, low heels, sheared heels, and medial-to-lateral imbalance can create or worsen palmar foot pain.

Shoulder or Higher Limb Pain

Less common than owners think, but still possible.

Neurological or Back-Related Gait Changes

Poor coordination, back pain, or neck pain can change front limb movement.

The foot is common. The foot is not always the only problem.

Treatment Options for Palmar Foot Pain

Treatment depends on the exact diagnosis.

Therapeutic Trimming and Shoeing

This is often the foundation.

Treatment may include:

• Shortening breakover

• Rolling or rockering the toe

• Correcting hoof-pastern axis

• Supporting the palmar foot

• Protecting thin soles

• Improving heel load-sharing

• Addressing sheared or underrun heels

• Using radiographs to guide trimming

• Shorter shoeing cycles

Merck lists trimming and shoeing changes as common first-line treatment, including rolling or rockering the toe and setting the shoe more palmarly to decrease breakover distance. (Merck Veterinary Manual)

Rest and Workload Modification

Some horses need reduced work while inflammation settles or while hoof mechanics are corrected.

This may include:

• Avoiding hard ground

• Avoiding tight circles

• Reducing jumping or speed work

• Using softer, consistent footing

• Gradual return once comfortable

NSAIDs

NSAIDs such as phenylbutazone or firocoxib may help pain and inflammation, but they do not correct hoof mechanics or structural injury. Merck lists systemic NSAIDs as part of conservative management. (Merck Veterinary Manual)

Coffin Joint or Navicular Bursa Injections

If inflammation is localised to the coffin joint or navicular bursa, targeted medication may help.

Merck lists distal interphalangeal joint or navicular bursa injections with corticosteroids, sometimes with hyaluronic acid, as treatment options. (Merck Veterinary Manual)

Bisphosphonates

Tiludronate or clodronate may be considered when navicular bone-related pathology is part of the diagnosis. These are not general treatments for every heel pain case.

Biologics

PRP, IRAP, stem cells, or other biologic treatments may be considered for selected soft tissue lesions. Merck notes that biologics have been used in some cases with soft tissue lesions in the navicular region. (Merck Veterinary Manual)

Surgery

Surgical options may include navicular bursoscopy or palmar digital neurectomy in selected severe cases.

Neurectomy must be approached carefully. Merck warns that if the deep digital flexor tendon has appreciable injury, palmar digital neurectomy can allow overuse and potential DDFT rupture, so MRI is preferred before neurectomy. (Merck Veterinary Manual)

Smart Shoeing: The Practical Goals

A good vet-farrier plan should answer:

• Is the toe too long?

• Is breakover delayed?

• Are the heels underrun or crushed?

• Is the frog functional?

• Is the digital cushion compromised?

• Is sole depth adequate?

• Is the horse landing toe first, flat, or heel first?

• Does imaging show bone or soft tissue disease?

• Does the horse need support, elevation, protection, or a combination?

• Is the current shoe helping the diagnosis or just hiding pain?

A good shoeing plan should improve mechanics without sacrificing the long-term health of the back of the foot.

That is the line to walk.

What Should You Do Right Now?

If you suspect palmar foot pain:

1. Reduce Hard Work

Avoid hard ground, tight circles, jumping, sharp turns, speed work, and deep footing until the horse is assessed.

2. Watch the Landing

Look at whether the horse lands heel first, flat, or toe first. Toe-first landing is a useful warning sign.

3. Check Digital Pulses and Hoof Heat

Strong pulses or hot feet make laminitis or abscess more concerning.

4. Take Photos of the Feet

Take side, front, sole, heel, and standing-square views. Good photos help vets and farriers assess toe length, heel structure, and hoof-pastern axis.

5. Book a Vet Lameness Exam

Ask for proper localisation, not just a shoeing change.

6. Discuss Radiographs

Radiographs are useful for navicular bone assessment and hoof balance, including sole depth and palmar angle.

7. Consider MRI if the Diagnosis Does Not Add Up

If the horse blocks to the foot but radiographs do not explain the lameness, MRI may be needed.

8. Involve Your Farrier Early

The farrier plan should be based on the vet’s findings, not copied from another horse.

Common Mistakes Owners Make

Calling Every Heel Pain Case Navicular

Palmar foot pain can involve bone, tendon, bursa, ligament, joint, hoof capsule, or sole.

Changing Shoes Without a Diagnosis

A shoeing change may help, but it should match the painful structure and hoof mechanics.

Overusing Wedges

Wedges can provide short-term relief in selected cases, but they can be harmful if they overload weak or crushed heels without a long-term plan.

Ignoring the Frog and Digital Cushion

The palmar foot needs load-sharing and structural support, not just heel elevation.

Relying on Radiographs Alone

Radiographs are important, but soft tissue injuries inside the hoof often require MRI.

Assuming a Palmar Digital Nerve Block Means Navicular Bone Disease

The block localises the region, not the exact structure.

Waiting Until the Horse Is Very Lame

Early palmar foot pain is often easier to manage than chronic hoof capsule distortion and long-standing tendon or bursal injury.

Prevention and Long-Term Management

You cannot prevent every case, but you can reduce risk.

Practical steps include:

• Maintain regular farrier care

• Avoid long toes

• Improve breakover

• Monitor heel quality

• Avoid allowing heels to run forward

• Treat sheared heels early

• Use radiographs for chronic hoof imbalance

• Protect thin soles

• Avoid excessive concussion

• Avoid repeated hard work on poor footing

• Keep body weight sensible

• Address early stumbling or toe-first landing

• Investigate mild recurring foot soreness

• Match shoeing to discipline and surface

• Reassess shoeing every cycle, not once per year

The best prevention is not one shoe. It is consistent hoof balance and early attention when the horse starts changing how they land.

Myth vs Reality

Myth	Reality
Palmar foot pain always means navicular bone disease.	It can involve bone, tendon, bursa, ligaments, joint structures, hoof balance, or several at once.
Normal radiographs rule it out.	Soft tissue injuries can be present even when radiographs look normal.
Wedges are always the answer.	Wedges can help selected horses but may worsen weak or crushed heels without a long-term plan.
One shoe works for all navicular horses.	Treatment should match the structure injured, hoof shape, use, and imaging findings.
A palmar digital nerve block identifies navicular disease.	It identifies the pain region, not the exact structure.
Shoeing alone fixes every case.	Shoeing is often essential, but some horses also need medication, injections, rest, MRI, or workload changes.

FAQs About Palmar Foot Pain in Horses

Is palmar foot pain the same as navicular disease?

Not exactly. Palmar foot pain describes pain from the back of the foot. Navicular syndrome is one major cause, but the pain may come from the navicular bone, bursa, deep digital flexor tendon, ligaments, coffin joint, or hoof mechanics. (Merck Veterinary Manual)

How do vets diagnose palmar foot pain?

Vets usually use a lameness exam, hoof testers, gait assessment, diagnostic nerve blocks, radiographs, farrier assessment, and sometimes MRI. MRI is especially useful when soft tissue injury is suspected or radiographs do not explain the lameness. (Veterinary Medicine at Illinois)

Are wedges good for navicular horses?

Sometimes. Wedges can reduce deep digital flexor tendon tension and improve hoof-pastern alignment in selected horses, but they can also create problems if used on weak or crushed heels without palmar support and a long-term hoof plan. (Equipodiatry)

Can a horse recover from palmar foot pain?

Many horses improve with correct diagnosis, therapeutic farriery, workload changes, and targeted treatment. Chronic or advanced cases may need long-term management, and some horses relapse as the condition progresses. Merck notes that navicular syndrome often requires lifelong treatment. (Merck Veterinary Manual)

When should I call a vet?

Call a vet if your horse is repeatedly short-strided, lame on circles, worse on hard ground, toe-first landing, stumbling, sensitive over the heels, or not improving after farrier changes. Call urgently for sudden severe lameness, strong digital pulses, hot feet, non-weight-bearing lameness, or suspected puncture wound.

The Bottom Line

Palmar foot pain is not one disease.

It is a region of pain.

That region may involve the navicular bone, deep digital flexor tendon, navicular bursa, ligaments, coffin joint, heel structures, hoof capsule, or poor hoof mechanics. The horse may look like a classic navicular case, but the treatment only makes sense once the painful structure is identified.

The safest approach is:

• Localise the pain.

• Image the foot.

• Assess the hoof capsule.

• Involve the farrier early.

• Avoid copying another horse’s shoeing plan.

• Use wedges carefully.

• Improve breakover and palmar support.

• Use MRI when radiographs do not explain the pain.

• Treat bone, tendon, bursa, ligament, or joint disease differently.

• Manage the horse long term, not just until the next show.

A sore heel is not a diagnosis.

A good diagnosis is what turns heel pain from guesswork into a plan.

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If your horse has heel pain, short choppy movement, toe-first landing, suspected navicular syndrome, or repeated farrier changes that are not helping, ASK A VET™ can help you organise hoof photos, lameness videos, radiographs, MRI findings, and questions to discuss with your treating vet and farrier.