Horse Tendon Injury: What To Do in the First 48 Hours

The first mistake owners make is hoping a hot, swollen tendon will “settle overnight.” Sometimes it does. Sometimes that is the moment a small injury becomes a season-ending one.

By Dr Duncan Houston

A tendon injury in a horse often starts quietly.

A little heat down the back of the cannon bone. A tendon that feels slightly thicker than the opposite leg. A small amount of swelling after work. Maybe the horse is only mildly lame, or not obviously lame at all.

That is why tendon injuries are dangerous. They do not always announce themselves with drama at the start. But if the horse keeps working on an injured tendon, the damage can worsen quickly.

The safest first response is simple: stop work, cool the limb, restrict movement, protect the leg, and call your vet. The goal in the first 48 hours is not to “fix” the tendon. It is to prevent further damage, control the acute inflammation, and get the injury assessed properly.

Quick Answer

At the first sign of a suspected tendon injury in a horse, stop work immediately, keep the horse quiet, apply cold therapy, use a correct supportive bandage if you know how to wrap safely, and contact your veterinarian. Acute tendon injuries commonly cause heat, swelling, pain on palpation, and variable lameness, and ultrasonography is the main diagnostic tool used to confirm which tendon is injured and how severe the lesion is. Early treatment usually focuses on stall rest, cold therapy, compression bandaging where appropriate, anti-inflammatory pain relief under veterinary direction, and then a structured rehabilitation plan based on clinical exams and repeat imaging. (MSD Veterinary Manual)

First 48 Hours: What To Do Immediately

Step	What to do	Why it matters
1	Stop work immediately	Prevents further tendon fibre damage
2	Keep the horse quiet	Reduces loading on the injured structure
3	Apply cold therapy	Helps reduce heat, swelling, pain, and inflammation
4	Bandage correctly if trained	Helps control swelling, but poor wrapping can cause harm
5	Call your vet	The injury needs diagnosis, not guessing
6	Arrange ultrasound when appropriate	Confirms the structure involved and guides rehab
7	Do not return to exercise early	Tendons feel better before they are strong

The big rule: do not test the leg repeatedly. Trotting, lunging, turning tightly, or “just seeing if it improves” can make the injury worse.

What Counts as a Tendon Injury?

When horse owners talk about tendon injuries, they are often talking about the flexor tendons at the back of the lower limb.

The most common structures involved include:

• Superficial digital flexor tendon, often called the SDFT

• Deep digital flexor tendon, often called the DDFT

• Check ligament

• Suspensory ligament, technically a ligament but often discussed in the same soft tissue injury group

• Tendon sheath structures when swelling or wounds are involved

The SDFT is a common injury site in horses doing fast work, especially racehorses and performance horses. MSD Veterinary Manual notes that SDFT injuries commonly occur in the forelimb of Thoroughbred racehorses and are typically overstrain injuries in the mid-metacarpal region, often with a central core lesion. Deep digital flexor tendon injuries can be harder to detect externally, especially when they occur in compressed regions such as the fetlock or inside the hoof capsule. (MSD Veterinary Manual)

In practice, tendon injuries are not all the same. A mild strain, a central core lesion, a tendon sheath problem, a deep digital flexor tear inside the foot, and a traumatic tendon laceration are completely different conversations.

That is why the first treatment step is control. The second step is diagnosis.

Early Signs of a Tendon Injury

A tendon injury may show up as:

• Heat down the back of the cannon bone

• Swelling along the tendon

• A tendon that feels thicker than the opposite limb

• Pain when the tendon is palpated

• A bowed appearance

• Mild to severe lameness

• Reduced performance

• Shortened stride

• Reluctance to load the limb

• Filling that returns after exercise

• A dropped or hyperextended fetlock in severe cases

MSD Veterinary Manual describes acute tendon injuries as being characterised by heat, swelling, pain, and varying degrees of lameness depending on severity and location. Severe SDFT injuries may cause fetlock hyperextension, while severe DDFT injuries can alter the way the toe loads. (MSD Veterinary Manual)

A key point: lack of obvious lameness does not rule out a tendon injury.

Some horses are surprisingly stoic. Others show swelling before they show much lameness. The tendon can be damaged internally before the outside of the leg looks dramatic.

Why the First 48 Hours Matter

The first 48 hours are about damage control.

During the acute phase, the goals are to:

• Stop further fibre disruption

• Reduce excessive inflammation

• Reduce swelling

• Reduce pain

• Prevent lesion progression

• Keep the horse from loading the tendon aggressively

• Prepare for accurate veterinary assessment

MSD Veterinary Manual states that tendinitis in horses is best treated in the early acute stage, with stall rest and aggressive treatment of swelling and inflammation using cold packs and systemic anti-inflammatory agents. It also lists cold hydrotherapy, compression bandaging, corrective shoeing, and controlled exercise as key components of conservative management. (MSD Veterinary Manual)

The danger is thinking the first 48 hours are just about making the leg look prettier. They are not. They are about protecting the tendon before the full extent of injury is known.

Step 1: Stop Work Immediately

If you feel heat, swelling, pain, or thickening along a tendon, stop work immediately.

Do not:

• Finish the lesson

• Trot one more circle

• Jump one more fence

• Lunge to “see if it improves”

• Turn the horse out in a large paddock

• Walk for miles to “cool it out”

• Put the horse back into normal work the next day because the swelling looks smaller

This is the moment where boring decisions save future months of rehab. Boring is good. Boring is cheap. Boring does not involve six months of hand walking and your horse inventing new ways to be spicy on a lead rope.

Step 2: Keep the Horse Quiet

Move the horse calmly to a safe, clean, contained area.

Depending on severity, this may mean:

• Stable rest

• Small yard confinement

• Controlled hand walking only if advised

• No large paddock turnout

• No ridden work

• No lunging

• No forced trotting

If the horse is very lame, unstable, or has a dropped fetlock, minimise movement and call your vet urgently.

A fresh tendon injury is not a fitness problem. It is a load management problem. Every unnecessary step can matter if the tendon lesion is significant.

Step 3: Use Cold Therapy

Cold therapy is usually the safest first response for a fresh, hot, swollen tendon.

Cold therapy may help:

• Reduce pain

• Reduce swelling

• Reduce local blood flow

• Reduce excessive inflammatory activity

• Reduce heat in the tissues

• Limit further irritation in the acute phase

An AAEP Proceedings paper on thermal therapy in the equine metacarpal region notes that cold therapy applied within the first 24 to 48 hours after injury can decrease pain, swelling, local blood flow, and inflammatory mediator activity. The same paper found that ice water immersion produced the greatest tissue temperature changes compared with several other thermal methods tested. (IVIS)

Practical options include:

• Cold hosing

• Ice boots

• Ice water immersion

• Cold compression systems

• Cold packs designed for equine limbs

Many practical protocols use cold therapy for around 15 to 20 minutes at a time, repeated during the acute phase, but the best protocol depends on the horse, limb, injury severity, equipment, skin tolerance, and veterinary advice.

The goal is controlled cooling. The goal is not freezing the skin into a regret pancake.

Step 4: Bandage Correctly

Bandaging can help control swelling and protect the limb, but it must be done correctly.

A safe stable bandage usually requires:

• Clean, dry limb

• Full-thickness padding

• Even pressure

• No wrinkles

• No tight edges

• Correct height and overlap

• Matching support on the opposite limb when appropriate

• Regular checks for slipping, swelling, heat, or pressure sores

A badly applied bandage can cause pressure injury, tendon pressure, restricted circulation, or skin damage. If you are not confident wrapping, wait for your vet or an experienced handler.

There is also an important evidence point here. A Veterinary Evidence review found a lack of scientific evidence that bandaging alone promotes tendon healing after superficial digital flexor tendinopathy, although rigid bandaging or short-term immobilisation may help limit lesion propagation in selected cases during the early inflammatory phase. (Veterinary Evidence)

So bandaging is supportive. It is not magic.

Step 5: Be Careful With NSAIDs

NSAIDs such as phenylbutazone or flunixin may be recommended by your vet for pain and inflammation, but they should not be used casually before the horse is assessed.

Reasons to speak to your vet first include:

• The horse may need a lameness exam

• Pain relief can mask worsening signs

• NSAIDs have kidney, gut, and right dorsal colitis risks

• Dose and duration matter

• Dehydration or concurrent illness changes risk

• Some horses are already on medications that change the plan

MSD Veterinary Manual includes systemic anti-inflammatory agents as part of acute tendon injury management, but this should be vet-directed rather than owner-guesswork. (MSD Veterinary Manual)

The principle is simple: pain relief is often appropriate, but the diagnosis should not disappear under a layer of bute and optimism.

Step 6: Call Your Vet

Call your vet promptly if there is:

• Heat

• Swelling

• Pain on palpation

• Lameness

• A bowed tendon appearance

• Sudden performance loss

• Dropped fetlock posture

• A wound over or near the tendon

• Rapid swelling up the limb

• A history of previous tendon injury

• Any uncertainty about severity

A tendon injury is not something you diagnose by vibes, group chat opinions, or someone at the yard saying, “Mine had that and was fine.”

Sometimes they are fine. Sometimes they are not. The expensive part is guessing wrong.

Does a Horse Need Ultrasound Straight Away?

Ultrasound is one of the most important tools for diagnosing tendon injuries, but the timing is case-dependent.

MSD Veterinary Manual describes ultrasonography with high-frequency linear probes as the most commonly used and available diagnostic tool for documenting tendon injury in horses. It can show tendon enlargement, hypoechoic lesions, fibre disruption, and remodelling. MRI may be useful for deep digital flexor tendon lesions within the hoof capsule or more difficult regions. (MSD Veterinary Manual)

A vet may recommend:

• An early ultrasound to establish the affected structure and severity

• A repeat ultrasound after several days if swelling or lesion definition changes

• Follow-up scans during rehabilitation

• MRI if the suspected injury is inside the hoof capsule or not well explained by ultrasound

This is why the phrase “ultrasound within 48 to 72 hours” should be used carefully. Early assessment is critical, but the ideal scan timing depends on the injury. In some cases, a scan in the first few days is very useful. In others, repeating the scan later gives a clearer picture of the lesion.

The most important point is not one magical scan time. It is this: do not start rehab without knowing what structure is injured and how severe the damage is.

What Ultrasound Helps Decide

Ultrasound helps your vet assess:

• Which tendon or ligament is injured

• Whether there is a core lesion

• Cross-sectional area

• Fibre alignment

• Degree of disruption

• Swelling around the tendon

• Whether the lesion is improving

• Whether rehab can safely progress

• Whether treatment options such as PRP or stem cell therapy are worth discussing

EquiManagement’s report on SDFT treatment notes that rehab should be tailored rather than one-size-fits-all, and that ultrasound monitoring is used to assess echogenicity, fibre alignment, lesion cross-sectional area, and inflammation markers as exercise increases. (EquiManagement)

This matters because a tendon can look better on the outside before it is stronger on the inside.

That is the trap.

How Worried Should You Be?

Lower Risk

This is more likely when:

• There is mild warmth only

• No obvious swelling is present

• The horse is sound at walk

• The tendon feels the same as the opposite limb

• Heat settles quickly with rest and cold therapy

• There is no pain on palpation

• There is no bowed appearance

Action: stop work, cool the limb, monitor closely, and speak to your vet if heat returns, swelling develops, or the horse is not completely normal.

Moderate Risk

This is more likely when:

• There is mild swelling

• The tendon feels thicker than the opposite leg

• The horse is slightly lame

• Heat persists beyond 12 to 24 hours

• The horse reacts to tendon palpation

• Swelling increases after work

• Performance has dropped without another obvious cause

Action: stop work, restrict movement, apply cold therapy, bandage if safe, and book a veterinary assessment. Ultrasound may be needed.

High Risk

This is more likely when:

• The tendon is visibly bowed

• The horse is clearly lame

• The tendon is hot and painful

• Swelling appeared suddenly during or after exercise

• The injury involves a high-performance horse

• The horse has a previous tendon injury

• The fetlock looks lower than normal

• There is marked swelling down the back of the cannon region

Action: call your vet the same day. Do not ride, lunge, trot, or turn the horse out in a large area.

Critical

Treat this as urgent if:

• The horse is severely lame

• The horse is reluctant to bear weight

• The fetlock drops or appears unstable

• A tendon laceration is possible

• There is a wound over or near the tendon

• The limb swells rapidly

• The horse has fever or depression

• The horse is very painful

• A fracture, tendon sheath infection, cellulitis, or joint infection is possible

Action: call your vet immediately and keep the horse still.

When Is a Tendon Injury an Emergency?

A tendon injury is an emergency if there is any sign of major structural damage, severe pain, infection risk, or instability.

Call a vet urgently if your horse has:

• Sudden severe lameness

• Non-weight-bearing lameness

• Dropped fetlock posture

• A wound over the tendon

• A wound near a tendon sheath

• Rapid swelling up the limb

• Severe pain on palpation

• Heat and swelling worsening over hours

• Fever, depression, or reduced appetite

• Suspected tendon laceration

• Swelling after trauma, kick, fall, or collision

• Any concern for fracture or joint infection

Do not walk the horse around to “see how bad it is” if the limb looks unstable or the horse is severely lame.

What Else Can Look Like a Tendon Injury?

Not every swollen leg is a tendon injury, and not every tendon injury looks obvious.

Important rule-outs include:

Suspensory Ligament Injury

Suspensory injuries can cause lameness, swelling, poor performance, and pain on palpation. They often need ultrasound and a different rehabilitation plan.

Check Ligament Injury

Check ligament injuries can create swelling and thickening near the back of the cannon region and can be confused with tendon injury.

Deep Digital Flexor Tendon Injury

Deep digital flexor tendon injuries may be difficult to detect externally, especially when they occur within the hoof capsule. MSD Veterinary Manual notes that MRI can be beneficial for DDFT lesions in the hoof capsule and certain proximal limb regions. (MSD Veterinary Manual)

Tendon Sheath Inflammation or Infection

Swelling involving a tendon sheath can be serious, especially if there is a nearby wound.

Cellulitis

Cellulitis can cause a hot, swollen limb and lameness, often with more diffuse swelling than a tendon lesion.

Hoof Abscess

A hoof abscess can cause sudden lameness and may lead to limb swelling, but the primary pain source is the foot.

Splint Bone Injury

Splint pain or fracture can cause localised swelling and lameness around the cannon bone.

Joint Injury

Fetlock, knee, hock, or coffin joint pain can alter loading and create secondary soft tissue strain.

Fracture

Sudden severe lameness after fast work or trauma should keep fracture on the list until ruled out.

The point is not to make owners panic. The point is to avoid treating every hot leg as “just a strain.”

What To Do Right Now

If you suspect a tendon injury, follow this plan.

1. Stop Work

Dismount or stop exercise immediately. Do not continue because the horse is “only slightly off.”

2. Move the Horse Calmly

Take the horse to a stable, small yard, or safe contained area. Avoid unnecessary walking.

3. Compare Both Limbs

Check both front legs or both hind legs side by side.

Look and feel for:

• Heat

• Swelling

• Thickening

• Pain

• Bowed tendon shape

• Digital pulse changes

• Fetlock position

• Wounds

• Difference from the opposite limb

4. Apply Cold Therapy

Cool the affected area using cold hosing, ice boots, or ice water immersion if safe and practical.

5. Bandage Only If You Can Do It Properly

Use full padding and even pressure. Do not apply a tight, thin, uneven wrap.

6. Call Your Vet

Describe what you found, when it started, what the horse was doing, whether there is lameness, and whether there is a wound.

7. Restrict Movement

Keep the horse quiet until your vet gives a plan.

8. Do Not Restart Exercise Early

A tendon injury is not cleared because swelling has gone down for one morning.

What Not To Do

Avoid these mistakes:

• Do not ride through it

• Do not lunge the horse to check

• Do not turn out in a large paddock

• Do not apply heat to a fresh hot tendon

• Do not use tight bandages

• Do not rely on stable boots to fix it

• Do not start NSAIDs without speaking to your vet

• Do not inject anything into or around the tendon without a diagnosis

• Do not assume no lameness means no tendon lesion

• Do not start rehab based only on how the leg looks

MSD Veterinary Manual specifically states that intratendinous corticosteroid injections are contraindicated in tendinitis because they inhibit repair mechanisms. (MSD Veterinary Manual)

That one deserves to be blunt: tendon injuries are not the place for random injections and crossed fingers.

How Rehabilitation Usually Progresses

Tendon rehabilitation must be structured and adjusted to the individual horse.

A very general framework looks like this:

Phase	Main goal	Typical focus
First 48 hours	Control acute injury	Rest, cold therapy, swelling control, vet assessment
First 1 to 2 weeks	Define injury and prevent worsening	Restricted movement, imaging, careful bandaging, pain control
Weeks 2 to 8	Begin early repair support	Controlled exercise only if advised
2 to 4 months	Build controlled loading	Gradual hand walking or controlled walking plan
4 to 6 months	Progress loading carefully	Trot may be introduced in selected cases if imaging supports it
6 to 12 months	Remodel and return gradually	Progressive conditioning and repeat ultrasound checks

This is not a prescription. It is a framework. The actual plan depends on the tendon, lesion size, horse discipline, ultrasound findings, lameness, age, previous injury history, and response to treatment.

EquiManagement summarises Roger Smith’s guidance that physical rehabilitation is critical in the subacute or chronic phase of SDFT injuries to promote scar organisation, remodelling, and reduce re-injury risk. It also reports that walking is gradually increased, trot may be introduced after around 4 to 5 months in selected cases, and ultrasound monitoring every three months or after exercise-level changes can guide progression. (EquiManagement)

Why You Should Not Rush the Return to Work

Tendons heal slowly because the repaired tissue is not identical to normal tendon.

A 2024 Equine Veterinary Education review explains that tendon repair often involves fibrous scar tissue that is structurally and functionally different from normal tendon, creating stiffness and higher strain around the repaired area. That helps explain why re-injury is such a major problem. (WEVA)

The same review reports SDFT re-injury rates of 40 to 50 percent in sport horses and 50 to 60 percent in National Hunt racehorses, with very poor return-to-racing outcomes reported in some flat racing populations. (WEVA)

So the issue is not just getting the horse sound.

The issue is getting the tendon strong enough, organised enough, and loaded gradually enough that the horse does not return to work just in time to break it again.

That is the cruel little tendon goblin. It makes them look better before they are actually ready.

Treatment Options After the Initial Phase

Once the injury is diagnosed, treatment may include:

• Continued rest

• Cold therapy in the acute phase

• Compression bandaging where appropriate

• Controlled exercise

• Corrective farriery

• NSAIDs under veterinary guidance

• Repeat ultrasound

• Shockwave therapy in selected cases

• PRP in selected cases

• Stem cell therapy in selected cases

• Splinting or immobilisation in severe cases

• Surgery in selected cases

• MRI for deep or difficult lesions

• Long-term rehabilitation planning

MSD Veterinary Manual notes that shockwave therapy and intralesional treatments such as stem cell or platelet-rich plasma products are now common forms of treatment, although evidence varies and treatment choice should depend on the case. (MSD Veterinary Manual)

The 2024 Equine Veterinary Education review also emphasises that many proposed tendon therapies have a weak evidence base, and that treatment should be chosen based on the type, location, and stage of the injury. (WEVA)

Translation: modern treatments can help, but there is no magic tendon button.

Common Mistakes Owners Make

Waiting to See If It Settles

Some mild filling does settle. But heat, pain, tendon thickening, or lameness deserves respect. Waiting too long can allow the lesion to worsen.

Continuing Work Because the Horse Is Not Very Lame

Some tendon injuries are not dramatically lame at the start. The tendon can still be damaged.

Using Heat Too Early

Heat is not appropriate for a fresh, hot, swollen tendon. Cold is usually the safer early option.

Wrapping Too Tightly

A bad bandage can create a second injury. Full padding and even pressure matter.

Skipping Ultrasound

You cannot accurately rehab a tendon injury if you do not know the lesion size, location, and fibre pattern.

Turning Out Too Soon

Large turnout plus a fresh tendon injury plus one dramatic spook is how owners accidentally extend the rehab plan.

Returning to Work When the Leg Looks Normal

Swelling can improve before tendon strength returns. Clinical appearance is not the same as internal healing.

Believing One Treatment Will Fix Everything

PRP, stem cells, shockwave, shoes, bandages, and medications all sit inside a bigger plan. The rehab is still the main event.

How To Reduce the Risk of Tendon Injuries

Not all tendon injuries can be prevented, but risk can be reduced.

Practical prevention includes:

• Build fitness gradually

• Avoid sudden jumps in workload

• Avoid fast work on tired horses

• Avoid deep, uneven, slippery, or inconsistent footing

• Maintain regular farrier care

• Correct hoof imbalance early

• Avoid persistent training when heat or swelling is already present

• Warm up properly

• Cool down properly

• Monitor legs after hard work

• Manage body weight

• Vary training surfaces when possible

• Allow recovery days

• Investigate subtle lameness early

• Use repeat imaging for previous tendon injuries

• Return to work slowly after any soft tissue injury

MSD Veterinary Manual lists overextension, poor conditioning, fatigue, poor racetrack conditions, persistent training when inflammatory tendon problems already exist, improper shoeing, poor conformation, and poor training as predisposing factors for SDFT tendinitis. (MSD Veterinary Manual)

The prevention mindset is simple: tendons hate sudden load, fatigue, bad footing, poor preparation, and wishful thinking.

Myth vs Reality

Myth	Reality
“If the horse is not very lame, it cannot be serious.”	Tendon injuries can be significant even when lameness is mild.
“Cold therapy fixes tendon injuries.”	Cold helps the acute phase. Diagnosis and rehab determine outcome.
“Bandages heal tendons.”	Bandages may help swelling or protection, but they do not rebuild tendon fibres.
“Ultrasound only matters if the horse is very lame.”	Ultrasound helps define the lesion and guide safe rehab.
“Once swelling is gone, the tendon is healed.”	Tendon remodelling takes months. External appearance can be misleading.
“A treatment injection means rehab can be faster.”	Regenerative therapies do not remove the need for controlled loading and monitoring.

FAQs About Initial Treatment of Tendon Injuries in Horses

Should I cold hose a suspected tendon injury?

Yes, cold therapy is usually appropriate for a fresh, hot, swollen tendon injury while you organise veterinary advice. Cold hosing or ice therapy can help reduce heat, swelling, and pain in the acute phase. (IVIS)

Should I wrap a tendon injury?

A correct supportive stable bandage may help control swelling, but poor bandaging can cause harm. Use full padding and even pressure, and do not wrap tightly. If you are unsure, wait for your vet or an experienced handler.

When should ultrasound be done?

Ultrasound timing depends on the case. Some horses benefit from early ultrasound, while others need repeat scans after the lesion becomes clearer or as rehab progresses. The key is that ultrasound should guide the diagnosis and return-to-work plan. (MSD Veterinary Manual)

Can I give bute for a tendon injury?

Only after speaking with your vet. NSAIDs may be useful for pain and inflammation, but dose, duration, diagnosis, kidney risk, gut risk, and masking of clinical signs all matter.

How long does a tendon injury take to heal?

Mild injuries may recover faster, but meaningful tendon lesions often require months of controlled rehabilitation. Some horses need 6 to 12 months before full return to work, depending on lesion severity, discipline, ultrasound findings, and response to rehab.

The Bottom Line

At the first sign of a suspected tendon injury, your job is not to diagnose the exact lesion from the outside of the leg.

Your job is to protect the tendon.

Stop work. Keep the horse quiet. Apply cold therapy. Bandage correctly if you know how. Call your vet. Use ultrasound to understand what is actually injured. Then follow a controlled rehabilitation plan based on the horse’s progress, not just how the leg looks on a good morning.

Tendon injuries reward early caution and punish wishful thinking. A quiet first 48 hours can save months of frustration later.

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If your horse has heat, swelling, pain, or a possible tendon injury and you are unsure how urgent it is, ASK A VET™ can help you organise the signs, understand what matters, and decide when hands-on veterinary assessment is needed.