Navicular Syndrome in Horses: Heel Pain, Diagnosis and Treatment

By Dr Duncan Houston

Navicular lameness is one of the classic causes of chronic front foot pain in horses, but the old phrase “navicular disease” can make the problem sound too simple.

The pain may involve the navicular bone, but it can also involve the navicular bursa, deep digital flexor tendon, collateral sesamoidean ligaments, distal impar ligament, coffin joint region, heel structures, hoof capsule, frog, digital cushion, and overall hoof balance.

That is why many vets now think in terms of palmar foot pain or navicular syndrome, not just “navicular disease.”

The most important step is not choosing Osphos, Tildren, a wedge shoe, or an injection. The most important step is working out which structure is actually painful. Without that, treatment becomes expensive guessing with a horseshoe attached.

Quick Answer

Navicular syndrome is a common cause of chronic front limb heel pain in horses, but it is not always limited to the navicular bone. It can involve bone, tendon, ligaments, the navicular bursa, coffin joint region, and hoof balance. Diagnosis usually needs a lameness exam, hoof testers, diagnostic nerve blocks, radiographs, farrier assessment, and sometimes MRI because radiographs do not show the deep soft tissues inside the hoof. Osphos and Tildren are FDA-approved bisphosphonates for controlling clinical signs associated with navicular syndrome in horses 4 years and older, but they are most logical when bone-related disease is part of the case, not when the main problem is soft tissue injury. (Merck Veterinary Manual)

What Is Navicular Syndrome?

Navicular syndrome is a chronic pain syndrome involving the back of the horse’s foot.

It was historically called navicular disease because vets focused heavily on visible changes in the navicular bone. Modern imaging has changed that view. The navicular apparatus includes multiple structures, and any of them may contribute to heel pain.

Important structures include:

• Navicular bone

• Navicular bursa

• Deep digital flexor tendon

• Collateral sesamoidean ligaments

• Distal impar ligament

• Coffin joint region

• Digital cushion

• Frog and heel structures

• Palmar hoof capsule

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. That is why the term “syndrome” is more accurate than treating every case as a single bone disease. (Merck Veterinary Manual)

Signs of Navicular or Heel Pain in Horses

Navicular-type heel pain often develops gradually.

Common signs include:

• Short, choppy front limb stride

• Stumbling or tripping

• Toe-first landing

• Worse lameness on hard ground

• Worse lameness on circles

• Reluctance to turn tightly

• Pointing one front foot

• Shortened stride downhill

• Heel or frog sensitivity with hoof testers

• Reduced performance

• Lameness that seems to shift between front feet

• Improvement after palmar digital nerve blocks

Many horses are bilaterally affected, meaning both front feet are painful, but one side often looks worse. That can make the lameness look confusing because blocking or treating one foot may reveal pain in the other. (Merck Veterinary Manual)

A common owner description is: “He feels short in the shoulders.”

In practice, the shoulder is often innocent. The horse is shortening the front stride to avoid loading the painful back of the foot.

Why Radiographs Are Not Always Enough

Radiographs are important, but they are not the whole story.

X-rays can show:

• Navicular bone shape

• Enlarged synovial fossae

• Sclerosis

• Cyst-like lesions

• Distal border fragments

• Flexor cortex irregularity

• Coffin bone alignment

• Sole depth

• Palmar angle

• Hoof balance

But X-rays do not properly show the deep digital flexor tendon, navicular bursa, collateral sesamoidean ligaments, or distal impar ligament inside the hoof capsule.

The University of Illinois explains that MRI is considered the gold standard for navicular syndrome because it can evaluate both the bony and soft tissue structures inside the hoof. A horse may have heel pain with minimal radiographic change if the main lesion is soft tissue. (Veterinary Medicine at Illinois)

That matters because a horse with navicular bone remodelling may be a reasonable bisphosphonate candidate. A horse with a deep digital flexor tendon tear may need a very different plan.

Why Diagnosis Comes Before Osphos or Tildren

Osphos and Tildren are bisphosphonate drugs. They affect bone turnover by inhibiting osteoclast activity, which is the activity of cells that break down bone. The FDA notes that bisphosphonates bind strongly to calcium and can remain in bone for long periods. (U.S. Food and Drug Administration)

That mechanism makes most sense when bone remodelling or bone pain is part of the diagnosis.

It makes much less sense when the main pain source is:

• Deep digital flexor tendon injury

• Navicular bursa inflammation

• Distal impar ligament injury

• Collateral sesamoidean ligament injury

• Coffin joint pain

• Thin soles

• Hoof abscess

• Laminitis

• Poor hoof balance without confirmed bone pathology

The clinical rule is simple:

A palmar digital nerve block tells you the pain is in the back of the foot. It does not tell you whether Osphos or Tildren is the right treatment.

Osphos and Tildren: What Are They?

Osphos and Tildren are both bisphosphonate medications approved for horses with clinical signs associated with navicular syndrome.

Drug	Active ingredient	Route	Main use
Osphos	Clodronate disodium	Intramuscular injection	Control of clinical signs associated with navicular syndrome in horses 4 years and older
Tildren	Tiludronate disodium	Intravenous infusion	Control of clinical signs associated with navicular syndrome in horses 4 years and older

Osphos is given intramuscularly, while Tildren is given intravenously as a slow infusion. Both are prescription drugs and must be used under veterinary direction. (U.S. Food and Drug Administration)

Does Osphos Work?

Osphos can help some horses with navicular syndrome, especially when the case fits bone-associated disease.

The official DailyMed label reports that in clinical field data, 74.7% of Osphos-treated horses were treatment successes at Day 56 compared with 3.3% of saline-treated horses. At Day 180, the estimated overall success rate for Osphos was 65.4%. (DailyMed)

That is useful, but it is not a guarantee.

It means Osphos can be a valuable tool in selected cases, not that every horse with sore heels should receive it.

The most important question is still: does this horse’s pain source match the drug?

Does Tildren Work?

Tildren may also improve clinical signs in selected navicular syndrome cases. It is given by slow intravenous infusion and works through a similar bone-resorption pathway.

The FDA groups Tildren and Osphos together as bisphosphonates approved for navicular syndrome, but they have different administration routes and safety considerations. (U.S. Food and Drug Administration)

Tildren is not an instant treatment. Its maximum effect may take weeks to months, and it should be part of a full plan involving farriery, diagnosis, and workload management.

Safety Concerns With Bisphosphonates

Bisphosphonates are not harmless “navicular injections.”

Important risks and cautions include:

• Colic signs

• Abdominal discomfort or agitation

• Changes in intestinal motility

• Kidney stress or renal injury

• Electrolyte and mineral shifts

• Calcium, magnesium, and potassium changes

• Caution in HYPP horses

• Caution in horses with cardiac disease

• Caution in horses with kidney disease

• Avoidance in horses under 4 years old

• Avoidance in pregnant or lactating mares

• Avoidance in breeding horses where safety has not been evaluated

The FDA states that bisphosphonates can cause colic signs, may affect calcium, magnesium, and potassium concentrations, and should be used cautiously in horses with conditions affecting mineral or electrolyte balance, such as HYPP or hypocalcemia. The FDA also states safe use has not been evaluated in horses under 4 years old, breeding horses, pregnant mares, or lactating mares. (U.S. Food and Drug Administration)

Osphos product information also warns against use in horses with impaired renal function or a history of renal disease. (Dechra)

NSAID Warning: Bute and Banamine Matter

This is a major safety point.

NSAIDs such as phenylbutazone, flunixin, and other anti-inflammatories can stress the kidneys. The FDA warns that concurrent use of NSAIDs with Tildren or Osphos may increase the risk of renal toxicity and acute renal failure. It also states that the 48 hours before and 48 hours after bisphosphonate treatment may be an especially risky window, although no exact safe window has been established. (U.S. Food and Drug Administration)

So do not assume a horse should automatically get Banamine before or after Osphos or Tildren.

A vet should review:

• Recent NSAID use

• Hydration status

• Kidney values

• Current colic risk

• Other medications

• Whether safer supportive options are needed

How Worried Should You Be?

Low Concern

This is more likely when:

• The horse is only mildly short-strided.

• The horse is sound at walk.

• There is no strong digital pulse.

• The lameness is intermittent and mild.

• Hoof balance issues are mild.

• The horse improves with rest, farriery changes, or softer footing.

Action: reduce hard work, avoid hard ground and tight circles, and organise a vet-farrier review if signs persist.

Moderate Concern

This is more likely when:

• Lameness is visible at trot.

• The horse is worse on circles or hard ground.

• The horse lands toe first.

• Hoof testers show heel or frog pain.

• The horse has long toes, low heels, crushed heels, or poor breakover.

• Performance is declining.

Action: book a veterinary lameness exam. Radiographs and diagnostic blocks are usually needed before deciding on treatment.

High Concern

This is more likely when:

• Lameness is recurrent or persistent.

• Palmar digital nerve blocks improve the lameness.

• Radiographs show navicular bone changes.

• MRI shows bone, tendon, bursa, or ligament lesions.

• Previous farrier changes have failed.

• The horse keeps relapsing when work increases.

Action: a full treatment plan is needed. This may include therapeutic farriery, MRI, targeted injections, bisphosphonates, rest, workload changes, or referral-level treatment.

Critical

Treat this as urgent if:

• The horse is suddenly severely lame.

• The horse is non-weight-bearing.

• The hoof is hot with a strong digital pulse.

• Laminitis is possible.

• A hoof abscess is possible.

• A nail or puncture wound is present.

• The horse is lame in multiple feet.

• The horse cannot turn or walk comfortably.

Action: call your vet promptly. Sudden severe foot pain is not routine navicular management.

When Is This an Emergency?

Chronic navicular syndrome is usually not a same-hour emergency.

Sudden or severe foot pain can be.

Call your vet urgently if your horse has:

• Sudden severe lameness

• Non-weight-bearing lameness

• Strong or bounding digital pulses

• Hot painful feet

• Reluctance to move

• Rocked-back stance

• Pain in more than one foot

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

• Swelling above the hoof

• Fever or depression

• Severe worsening after shoeing

• Severe colic signs after Osphos or Tildren

• Weakness, trembling, collapse, or abnormal behaviour after bisphosphonate treatment

Do not assume sudden heel pain is navicular. Hoof abscess, laminitis, puncture wounds, fractures, and deep infections can look similar early.

What Else Can Look Like Navicular Lameness?

Before treating a horse for navicular syndrome, your vet may need to rule out:

Hoof Abscess

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

Laminitis

Can cause bilateral front foot pain, bounding pulses, reluctance to move, and a rocked-back stance.

Deep Digital Flexor Tendon Injury

Often invisible on radiographs and may require MRI.

Navicular Bursa Pain

Can create heel pain and may require bursal medication or referral care.

Coffin Joint Pain

May overlap with palmar foot pain and may respond to different 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.

Poor Hoof Balance

Long toes, low heels, crushed heels, sheared heels, and delayed breakover can create or worsen heel pain.

White Line Disease or Hoof Wall Instability

Can contribute to chronic foot pain, cracks, and abscesses.

Neck, Shoulder, or Higher Limb Pain

Less common than foot pain, but worth considering if foot blocks and imaging do not explain the case.

How Vets Diagnose Navicular Syndrome

A good diagnosis is stepwise.

1. History

Your vet will ask:

• How long has the horse been lame?

• Is it worse on hard ground?

• Is it worse on circles?

• Does the horse stumble?

• Does the horse land toe first?

• Has shoeing changed?

• Does rest help?

• Has the horse had previous heel pain?

• What treatments have already been tried?

2. Hoof and Limb Examination

This includes:

• Hoof testers

• Digital pulse assessment

• Hoof shape review

• Toe length

• Heel height

• Frog and digital cushion assessment

• White line and sole depth assessment

• Landing pattern

• Limb conformation

3. Gait Assessment

The horse may be assessed:

• In walk

• In trot

• On hard ground

• On soft ground

• On circles

• On straight lines

• Under saddle if the problem is subtle or performance-related

4. Diagnostic Nerve Blocks

Palmar digital nerve blocks are commonly used to localise pain to the back of the foot. But they do not identify the exact injured structure.

That is where imaging comes in.

5. Radiographs

Radiographs assess the navicular bone and hoof balance.

They are essential, but they cannot fully assess soft tissue inside the hoof.

6. MRI

MRI is often the most useful tool when the horse blocks to the foot but radiographs do not explain the lameness. MRI can identify deep digital flexor tendon lesions, navicular bone oedema, navicular bursa pathology, ligament injuries, and multiple combined lesions. (Veterinary Medicine at Illinois)

Treatment Options for Navicular or Heel Pain

Treatment depends on the structure involved.

Therapeutic Trimming and Shoeing

This is often the foundation.

Goals may include:

• Shortening breakover

• Improving hoof-pastern alignment

• Supporting the palmar foot

• Protecting thin soles

• Supporting weak heels

• Improving heel-first or flatter landing

• Reducing deep digital flexor tendon strain

• Reducing excessive concussion

Common options include:

• Rolled toe

• Rockered toe

• Bar shoes

• Egg bar shoes in selected cases

• Pads

• Pour-in support

• Frog support

• Heel support

• Wedges in selected cases

• Shorter shoeing cycles

• Radiograph-guided trimming

The shoe should match the diagnosis. One horse’s navicular shoe is not automatically another horse’s answer.

Bisphosphonates: Osphos and Tildren

Bisphosphonates may be considered when navicular bone pathology is part of the case.

They are not a substitute for hoof balance, farrier work, or diagnosis.

Good candidates are more likely to have:

• Confirmed navicular syndrome

• Bone-related changes on radiographs or MRI

• Appropriate age and safety profile

• No kidney disease

• No recent high-risk NSAID use

• No breeding, pregnancy, or lactation concern

• A long-term hoof and workload plan

Poor candidates include horses with:

• Soft tissue-only injury

• Active kidney disease

• Age under 4 years

• Pregnancy or lactation

• HYPP risk without discussion

• Undiagnosed sudden severe foot pain

• A case where farriery has not been addressed

Coffin Joint or Navicular Bursa Injections

If pain is localised to the coffin joint or navicular bursa, targeted injections may help.

These may include corticosteroids, hyaluronic acid, or other medications depending on the diagnosis.

Regenerative Therapies

PRP, IRAP, stem cells, or other biologic therapies may be considered in selected soft tissue cases, especially when MRI identifies tendon or ligament injury.

NSAIDs

NSAIDs may help pain and inflammation in some cases, but they do not fix hoof mechanics or structural injury.

They also require caution around bisphosphonate treatment because of kidney risk. (U.S. Food and Drug Administration)

Workload and Footing Changes

Many horses need:

• Reduced work during flare-ups

• Less hard ground

• Less tight circling

• Less jumping or speed work temporarily

• More controlled return to work

• Better footing consistency

Surgery

Surgical options are reserved for selected cases and may include navicular bursoscopy or palmar digital neurectomy.

Neurectomy should be approached carefully, especially if the deep digital flexor tendon is damaged, because removing sensation can allow overuse and serious injury.

Common Mistakes Owners Make

Calling Every Heel Pain Case Navicular Bone Disease

Heel pain can come from bone, tendon, bursa, ligament, joint, sole, or hoof balance.

Treating Before Diagnosing

Osphos, Tildren, wedges, and injections should fit the diagnosis, not replace it.

Relying on Radiographs Alone

Radiographs matter, but normal X-rays do not rule out soft tissue injury.

Overusing Wedges

Wedges can help some horses short term, but they can worsen weak, crushed, or underrun heels if used without a long-term hoof plan.

Ignoring Farriery

No medication can outwork bad hoof mechanics forever.

Using NSAIDs Around Bisphosphonates Without Planning

Bute and Banamine around Osphos or Tildren can increase kidney risk. This needs veterinary planning. (U.S. Food and Drug Administration)

Expecting Osphos To Fix Soft Tissue Injury

If MRI shows the main lesion is tendon, bursa, or ligament related, a bone-targeted drug may not be the main answer.

What Should You Do Right Now?

If your horse has suspected navicular or heel pain:

1. Reduce Hard Work

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

2. Watch the Landing

Toe-first landing is a major clue that the horse may be avoiding heel loading.

3. Check Hoof Heat and Digital Pulses

Strong digital pulses or hot feet raise concern for laminitis, abscess, or acute inflammation.

4. Take Hoof Photos

Take side, front, sole, and heel photos. These help assess toe length, heel structure, frog size, and hoof-pastern axis.

5. Book a Vet Lameness Exam

Do not jump straight to Osphos, wedges, or injections.

6. Ask About Radiographs

Radiographs help assess the navicular bone, coffin bone, sole depth, hoof-pastern alignment, and farrier planning.

7. Consider MRI if the Case Does Not Add Up

If the horse blocks to the foot but radiographs do not explain the pain, MRI can be the difference between guessing and knowing.

8. Involve Your Farrier Early

This is a vet-farrier case. The best treatment plans are usually collaborative.

Prevention and Long-Term Management

Not every case can be prevented, but risk can be reduced.

Practical prevention includes:

• Regular farrier care

• Avoid long toes

• Maintain appropriate breakover

• Support the heels correctly

• Treat crushed or underrun heels early

• Use radiographs for chronic hoof imbalance

• Avoid excessive concussion on hard ground

• Build fitness gradually

• Avoid sudden workload spikes

• Keep body weight sensible

• Investigate stumbling or toe-first landing early

• Do not keep working through repeated heel soreness

• Match shoeing to the horse’s conformation and discipline

• Review shoeing every cycle, not once per year

Myth vs Reality

Myth	Reality
Navicular disease always means the navicular bone is the problem.	The pain may come from bone, tendon, bursa, ligament, joint, or hoof mechanics.
Normal radiographs rule out navicular-type pain.	Soft tissue injuries inside the hoof may require MRI.
Osphos works for every sore heel.	It is most logical when bone involvement is part of the diagnosis.
Wedges are always the answer.	Wedges may help selected horses, but can worsen weak heels without a long-term plan.
A palmar digital nerve block diagnoses navicular disease.	It localises pain to the back of the foot, but does not identify the exact structure.
Shoeing alone fixes every case.	Shoeing is essential, but some horses need medication, injections, MRI, rest, or workload changes.

FAQs About Navicular Lameness and Heel Pain

Is navicular syndrome the same as heel pain?

Not exactly. Heel pain describes the region. Navicular syndrome is one important cause of palmar foot pain, but the painful structure may be the navicular bone, bursa, deep digital flexor tendon, ligaments, coffin joint, or hoof capsule.

Does Osphos cure navicular disease?

No. Osphos controls clinical signs associated with navicular syndrome in some horses. It does not cure every case and does not replace diagnosis, hoof balance, farriery, or workload management. (DailyMed)

Is MRI necessary for navicular lameness?

Not always, but it is very useful when radiographs do not explain the pain, when soft tissue injury is suspected, or when treatment decisions depend on knowing whether bone, tendon, bursa, or ligament is involved. (Veterinary Medicine at Illinois)

Can a horse return to work with navicular syndrome?

Many horses can return to comfortable work with the right diagnosis, shoeing, medication, and workload changes. Chronic cases often need long-term management rather than a one-time fix.

When should I call a vet?

Call a vet if your horse is repeatedly short-strided, landing toe first, worse on circles, sore on hard ground, stumbling, or sensitive in the heel. Call urgently for sudden severe lameness, strong digital pulses, hot feet, or a suspected puncture wound.

The Bottom Line

Navicular lameness is not one simple disease.

It is a heel pain syndrome that may involve bone, tendon, ligament, bursa, joint, hoof balance, or several structures at once.

Osphos and Tildren can help selected horses, especially when navicular bone-related disease is part of the case. But they are not general-purpose heel pain treatments, and they carry real safety considerations, especially around kidney function, NSAID use, age, breeding status, pregnancy, lactation, HYPP risk, and electrolyte changes.

The best approach is:

• Localise the lameness.

• Image the foot.

• Identify the painful structure.

• Build the farrier plan around the diagnosis.

• Use bisphosphonates only when the case fits.

• Do not ignore soft tissue injury.

• Manage the horse long term.

A horse with sore heels does not need guesswork.

They need a proper diagnosis, a smart farrier plan, and treatment chosen for the structure that is actually hurting.

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If your horse has heel pain, suspected navicular syndrome, toe-first landing, chronic front limb lameness, or you are unsure whether Osphos or Tildren is appropriate, ASK A VET™ can help you organise hoof photos, lameness videos, radiographs, MRI findings, and the right questions to discuss with your treating veterinarian and farrier.