Can Infrared Thermography Diagnose Lameness in Horses?

Thermography can show abnormal heat patterns, but it should not replace a proper veterinary lameness exam.

By Dr Duncan Houston

Infrared thermography sounds like the dream lameness tool: point a camera at the horse, look for a bright red area, and suddenly the mystery is solved.

Unfortunately, horses are not that polite.

Thermography can be useful, but it detects skin surface temperature, not the actual structure underneath. It may show heat changes linked to inflammation, altered blood flow, pressure, loading changes, or compensation. What it cannot do by itself is confirm a tendon tear, fracture, joint injury, hoof abscess, neurological disease, or the exact source of lameness.

Used properly, thermography can help a vet decide where to look next. Used badly, it can waste money, delay diagnosis, and turn a colourful image into a very confident wrong answer.

Quick Answer

Infrared thermography can help screen for abnormal heat patterns in horses, but it does not diagnose most causes of lameness by itself. It may support a lameness workup by highlighting areas of altered surface temperature, inflammation, circulation, or pressure, but the findings must be interpreted alongside a veterinary exam, gait assessment, palpation, nerve blocks, radiographs, ultrasound, MRI, CT, scintigraphy, or neurological testing when needed. The American Academy of Thermology states that infrared imaging does not test structure and that suspected structural injuries may still require additional imaging or diagnostic studies.

What Is Infrared Thermography?

Infrared thermography is an imaging method that detects infrared radiation emitted from the body surface and converts it into a visual temperature map.

In simple terms, it shows warmer and cooler areas on the skin.

That matters because heat can be associated with inflammation, increased blood flow, soft tissue irritation, altered loading, pressure points, or circulatory changes. In horses, thermography has been used as an adjunct for assessing musculoskeletal stress, wound healing, post-surgical swelling, peripheral circulation, saddle fit concerns, and rehabilitation monitoring.

The American Academy of Thermology describes veterinary infrared imaging as a tool that can map circulatory changes, enhance the clinical examination, and help document musculoskeletal stress caused by training or treatment effects.

The key word is enhance.

Not replace.

How Does Thermography Work?

A thermographic camera measures thermal emission from the surface of the horse’s body. The software then displays temperature differences using colours or grayscale patterns.

A warmer area may appear red, orange, yellow, or white depending on the palette.

A cooler area may appear blue, green, purple, or darker.

But the colours are not the diagnosis.

A red area does not automatically mean tendon injury.

A cool area does not automatically mean nerve damage.

An uneven scan does not automatically mean the horse is lame from that exact spot.

The American Academy of Thermology notes that infrared imaging measures and maps thermal emission, with skin temperature influenced by the autonomic nervous system and inflammatory processes. It also states that infrared evaluations do not test structure, and that additional diagnostic studies may still be needed when structural injury is suspected.

That is the clinically important point. Thermography shows physiology. It does not show anatomy in the way X-rays, ultrasound, CT, MRI, or scintigraphy can.

What Can Thermography Tell You?

Thermography may help identify:

• Surface temperature asymmetry between left and right limbs

• Areas of increased heat

• Areas of unexpectedly reduced heat

• Possible superficial inflammation

• Changes in peripheral circulation

• Areas of abnormal loading

• Pressure patterns from tack or saddle fit

• Changes during healing or rehabilitation

• Regions that may deserve closer veterinary investigation

MSD Veterinary Manual describes thermography as a noninvasive imaging method that creates a picture of surface temperature and may help detect inflammation contributing to lameness through local heat changes. MSD also places thermography under physiologic imaging, meaning it evaluates circulation or metabolism rather than directly showing structure. (MSD Veterinary Manual)

In practice, thermography is most useful when the question is:

Where should we focus the next part of the exam?

It becomes risky when the question becomes:

Can this image replace the exam?

The answer is no.

What Can Thermography Not Diagnose by Itself?

Thermography should not be used alone to diagnose:

• EPM

• Fractures

• Tendon tears

• Ligament tears

• Hoof abscesses

• Joint infections

• Bone infections

• Tumours

• Gastric ulcers

• Navicular disease

• Deep digital flexor tendon injuries inside the hoof

• Suspensory ligament injuries

• Neurological disease

• The exact cause of back pain

• The exact source of lameness

Thermography may show an abnormal thermal pattern near a problem area, but that pattern does not prove the disease.

The American Academy of Thermology states that thermographic findings should guide the treating veterinarian in investigating the possible source of the abnormality, but response to treatment and further examination or testing may still be needed.

That is the safest owner takeaway: a thermal scan can raise a question, but it should not pretend to be the whole answer.

Thermography vs Other Lameness Diagnostics

Tool	What it helps with	Main limitation
Thermography	Surface heat patterns, asymmetry, inflammation clues, circulation changes	Does not directly image bones, joints, tendons, or deep structures
Physical exam	Heat, swelling, pain, range of motion, limb comparison	Subtle or multi-limb lameness can be difficult
Hoof testers	Foot pain localisation	Does not identify every foot problem
Flexion tests	Stressing regions to reveal pain patterns	Can be nonspecific
Nerve blocks	Localising pain to a region	Requires consistent lameness and careful interpretation
X-rays	Bone and joint changes	Limited for many soft tissue injuries
Ultrasound	Tendons, ligaments, fluid, soft tissue	Limited for some deep or hoof capsule structures
MRI	Deep soft tissue, foot pain, bone bruising	More expensive and less available
CT	Detailed bone imaging	Availability and cost vary
Scintigraphy	Bone turnover, multi-region or difficult lameness	Less specific and usually referral based

Merck Veterinary Manual states that diagnostic regional anaesthesia is valuable when the origin of pain remains uncertain after a thorough physical exam, because localising pain helps other diagnostics such as radiography, ultrasound, CT, scintigraphy, and MRI identify the cause more effectively. (Merck Veterinary Manual)

That is how thermography should be viewed: one possible part of the bigger workup, not the final verdict.

When Thermography Can Be Useful

Thermography can be helpful in selected cases, especially when performed under controlled conditions and interpreted by a trained veterinarian.

Subtle Lameness Screening

If a horse has vague poor performance, intermittent lameness, or subtle asymmetry, thermography may help highlight a region that deserves closer examination.

It does not diagnose the cause. It may help direct the next step.

Tendon, Ligament, and Soft Tissue Monitoring

A superficial tendon or ligament injury may produce increased heat over the affected region. Thermography may help monitor whether the heat pattern is improving, spreading, or returning during rehabilitation.

It still cannot show tendon fibre disruption or lesion size. That is where ultrasound or MRI may be needed.

Saddle Fit and Back Pressure

Thermography may show heat asymmetry across the back after ridden work, which can support a saddle fit investigation.

But saddle thermography must be interpreted carefully. Rider position, saddle movement, sweat, coat length, ambient temperature, workload, timing after exercise, and existing back pain can all alter the image.

Rehabilitation Tracking

Thermography may help track thermal trends over time, especially in horses returning from known injury.

The American Academy of Thermology lists monitoring progression and exercise protocols through post-injury rehabilitation as one veterinary use of infrared imaging.

Left to Right Comparison

Side-to-side comparison is often one of the most useful applications, especially when both limbs are imaged under the same conditions.

The catch is that horses are rarely perfect laboratory models. They stand in the sun, roll in mud, grow uneven coats, wear bandages, sweat asymmetrically, and generally behave like expensive chaos with legs.

Why Thermography Can Be Misleading

Thermography is highly sensitive. That is both its strength and its weakness.

A thermal pattern can be changed by:

• Sun exposure

• Wind

• Ambient temperature

• Humidity

• Recent exercise

• Sweat

• Wet hair

• Mud

• Thick coat

• Clipping

• Bandages

• Blankets

• Boots

• Tack contact

• Liniments

• Fly spray

• Topical medications

• Recent cold hosing

• Recent icing

• Heat packs

• Grooming

• Touching the scanned area

• Uneven weight-bearing

• Poor positioning

• Camera quality

• Operator skill

• Incorrect software settings

The American Academy of Thermology states that infrared imaging is highly sensitive to environmental factors and is contraindicated when factors such as sunshine, ambient temperature, drafts, hair coat, topical moisture, liniments, bandages, blankets, or harness contact cannot be controlled.

This is why quick outdoor scans, scans after exercise, scans after liniment, or scans taken in direct sun can be unreliable.

Thermography is not just “point and diagnose.” It is a controlled imaging technique.

Who Should Interpret Equine Thermography?

Thermography should be interpreted by a veterinarian trained in its use, ideally as part of a full veterinary assessment.

The American Academy of Thermology states that diagnostic, treatment, and prognosis questions should be referred to the veterinarian, and that only veterinarians trained in the required techniques should perform and interpret infrared imaging because painful conditions associated with skin temperature asymmetry can have complex causes.

This matters because the camera does not know whether heat is coming from:

• Primary injury

• Compensation from another limb

• Saddle pressure

• Skin disease

• Recent exercise

• Local irritation

• Bandage effect

• Topical product use

• Neurological change

• Vascular change

• Poor imaging conditions

The vet’s job is to decide whether the thermal pattern actually fits the horse.

Red Flags: When Thermography Is Being Oversold

Be cautious if someone claims thermography can:

• Diagnose EPM

• Diagnose fractures without X-rays

• Diagnose tendon tears without ultrasound or MRI

• Replace a lameness exam

• Replace nerve blocks

• Replace a veterinarian

• Confirm a joint infection

• Prove gastric ulcers

• Diagnose tumours

• Give a full treatment plan from the scan alone

• Tell you exactly which injection the horse needs

• Clear a horse for full work after injury without clinical assessment

• Diagnose deep internal disease from a surface heat pattern

• Provide reliable medical results from a phone plug-in thermal camera

The American Academy of Thermology states that industrial or personal thermal cameras that do not meet medical thermology specifications are not intended for medical thermology, and that phone plug-in thermal imagers are not adequate for medical thermology imaging.

That is a very clean owner rule:

Thermography can support a veterinary question. It should not be sold as a veterinary answer.

Can Thermography Diagnose EPM?

No.

Thermography should not be used to diagnose equine protozoal myeloencephalitis, known as EPM.

EPM is a neurological disease. It requires a neurological examination and appropriate laboratory testing. MSD Veterinary Manual states that EPM clinical signs can mimic other neurological diseases and that diagnostic support is obtained using serum to CSF titre ratios from ELISA or indirect fluorescent antibody test results. (MSD Veterinary Manual)

UC Davis describes EPM testing through quantitative antibody titres and serum to CSF ratios when serum and cerebrospinal fluid are submitted together, with laboratory submissions made by veterinarians. (vetmed.ucdavis.edu)

So if someone tries to diagnose EPM from a thermal scan alone, that is not advanced imaging. That is a diagnostic circus with a camera.

How Worried Should You Be About a Hot Spot on a Thermal Scan?

A hot spot is not automatically an emergency. It is a reason to ask better questions.

Low Concern

This is more likely when:

• The horse is sound

• There is no swelling

• There is no pain on palpation

• The thermal change is mild

• The scan was done after work

• The horse had uneven sun, sweat, mud, clipping, tack contact, or topical products

• The finding is not repeatable under controlled conditions

Action: do not panic. Recheck under better conditions and ask your vet whether the finding is clinically meaningful.

Moderate Concern

This is more likely when:

• The horse has mild or intermittent lameness

• There is a repeatable side-to-side temperature difference

• The area matches mild swelling or soreness

• The horse has performance changes

• The scan highlights a region that also reacts on palpation

• The finding persists after rest and controlled imaging

Action: book a veterinary lameness exam. Thermography may help guide where to focus, but further assessment is needed.

High Concern

This is more likely when:

• The horse is clearly lame

• There is heat, swelling, pain, or joint effusion

• The thermal abnormality matches a painful structure

• The horse has a tendon, ligament, joint, or hoof concern

• The horse is worsening over days

• The horse is unsafe under saddle

• A previous injury appears active again

Action: stop work and arrange veterinary assessment. Targeted imaging such as ultrasound or radiographs may be needed.

Critical

Treat this as urgent if:

• The horse is non-weight-bearing

• There is sudden severe lameness

• There is a wound near a joint, tendon sheath, or deep structure

• There is marked swelling up the limb

• The horse has fever or depression

• There are neurological signs

• A fracture is possible

• The horse has severe back pain after trauma

• The horse becomes weak, ataxic, or unsafe to move

Action: call your vet immediately. Do not rely on thermography to decide whether this is serious.

When Is Lameness an Emergency?

Call a vet urgently if your horse has:

• Sudden severe lameness

• Non-weight-bearing lameness

• A wound near a joint, tendon, tendon sheath, or hoof

• Rapid swelling

• Severe heat and pain

• A hot, swollen tendon

• A suspected fracture

• A nail or puncture wound in the foot

• Fever, depression, or reduced appetite

• Neurological signs such as weakness, stumbling, ataxia, or abnormal proprioception

• Collapse or inability to walk safely

• Severe pain after a fall, kick, or collision

Merck Veterinary Manual warns that if lameness has an acute onset, is severe, and fracture is suspected, exercise should not be performed because catastrophic breakdown may result. (Merck Veterinary Manual)

The main job in an emergency is not to get a prettier scan. It is to protect the horse and get the right veterinary care quickly.

What Should a Proper Thermography Appointment Include?

A useful thermography assessment should involve more than taking colourful pictures.

It should include:

• Clear reason for the scan

• Relevant history

• Current medications and treatments

• Recent exercise history

• Previous imaging or lameness results

• Controlled environment

• Clean, dry coat

• Removal of bandages, blankets, tack, boots, and wraps before imaging

• Avoidance of liniments, sprays, topical products, sweat, and wet hair

• Symmetrical positioning

• Left and right comparison

• Proper camera equipment

• Recorded temperature scale

• Veterinary interpretation

• Clear explanation of what the scan can and cannot say

• Recommendation for further diagnostics where needed

The American Academy of Thermology guidelines state that the patient should be clean, groomed, dry, and free from topical products, and that bandages, blankets, wraps, or other contact items should be removed before the thermal exam.

That is not fussy. That is how you avoid paying for a scan that mostly diagnoses “this horse had a rug on.”

What Should You Do If a Thermal Scan Shows an Abnormal Area?

Use the scan as a starting point, not the finish line.

1. Ask Whether the Finding Matches the Horse

Does the abnormal area match:

• Lameness?

• Swelling?

• Heat by hand?

• Pain on palpation?

• Reduced performance?

• A saddle fit concern?

• A known old injury?

• A recent change in workload?

If not, it may be incidental or environmental.

2. Repeat Under Controlled Conditions If Needed

If the scan was done after exercise, in sunlight, in wind, after liniment, with wet hair, or after bandage removal, results may be unreliable.

3. Stop Work If the Horse Is Lame or Painful

Do not keep riding because “it is only a thermal finding.” If the horse is lame or sore, reduce risk while the cause is investigated.

4. Book a Veterinary Lameness Exam

A proper exam may include palpation, gait assessment, hoof testers, flexion tests, nerve blocks, and targeted imaging.

Merck Veterinary Manual describes a lameness exam as including standing assessment, exercise evaluation, flexion testing, and diagnostic regional anaesthesia where needed, with neurological examination included when an obvious painful or mechanical cause is not found. (Merck Veterinary Manual)

5. Use Imaging That Matches the Suspected Problem

If the concern is bone, X-rays or CT may be needed.

If the concern is tendon or ligament, ultrasound or MRI may be needed.

If the concern is deep, complex, or multi-site, scintigraphy, MRI, or CT may be considered.

If the concern is neurological, a neurological exam and appropriate testing matter more than a thermal image.

What Else Can Cause Abnormal Heat Patterns?

An abnormal thermal pattern may be real, but not primary.

Possible explanations include:

Active Inflammation

Tendon, ligament, joint, muscle, hoof, skin, or wound inflammation may increase local surface temperature.

Compensatory Loading

A horse may overload one limb because another limb hurts. The hot region may be the compensation, not the original injury.

Saddle or Tack Pressure

Pressure, friction, and altered blood flow can create thermal asymmetry across the back.

Skin Disease

Dermatitis, rubbing, infection, allergy, or local irritation can create heat.

Recent Exercise

Work increases circulation and heat. Timing after exercise matters.

Bandage or Boot Effects

A wrapped limb may have altered temperature simply because it has been covered.

Topical Products

Liniments, poultices, sprays, cold therapy, heat therapy, and topical medications can alter readings.

Neurological or Vascular Changes

Some conditions may create reduced or altered blood flow rather than obvious heat.

Environmental Artefact

Sun, wind, humidity, clipping, wet hair, and uneven coat thickness can all distort results.

This is why the scan must be interpreted with the horse in front of you, not in isolation.

Common Mistakes Owners Make

Treating the Scan as the Diagnosis

A hot area is not the same as a diagnosis. It is a clue.

Skipping the Vet Exam

Thermography should not replace palpation, gait assessment, hoof testers, flexion testing, nerve blocks, or imaging when needed.

Scanning in Poor Conditions

Sun, wind, wet hair, sweat, recent exercise, blankets, bandages, and topical products can all distort results.

Letting a Non-Vet Create a Treatment Plan

A scan may capture a heat pattern, but diagnosis, prognosis, and treatment planning belong with a veterinarian.

Using Thermography for Conditions It Cannot Diagnose

EPM, fractures, internal disease, deep tendon lesions, joint infections, and many neurological conditions need appropriate diagnostics.

Chasing Every Colour Change

Not every colour change matters. The clinical pattern matters.

Waiting Too Long Because the Scan “Did Not Look Bad”

A normal or mild thermographic image does not rule out serious lameness, especially if the pain is deep, structural, or neurological.

How To Use Thermography Properly in a Lameness Workup

Thermography is most useful when it answers a focused question.

Better questions include:

• Is there a repeatable thermal asymmetry?

• Does this region match the horse’s pain response?

• Has the heat pattern improved during rehabilitation?

• Is the saddle creating uneven heat patterns?

• Is a known injury becoming active again?

• Does this help decide where to image next?

Poor questions include:

• Does my horse have EPM?

• Which injection does my horse need?

• Is this horse safe to compete tomorrow?

• Can I skip X-rays?

• Can I skip ultrasound?

• Can this replace nerve blocks?

• Is this definitely the cause of the lameness?

In a good workup, thermography may help narrow the search. It should not close the case before the case has actually been investigated.

Can Thermography Help With Saddle Fit?

It can help, but it is not the whole answer.

Thermography may show asymmetrical heat patterns across the back after the horse has been ridden. That can raise concern for uneven pressure, rider imbalance, saddle movement, or muscular response.

But saddle fit assessment still needs:

• Static saddle assessment

• Dynamic ridden assessment

• Back palpation

• Muscle symmetry assessment

• Girth and pad review

• Rider position review

• Lameness assessment if pain is present

Thermography may support the saddle fit conversation. It should not be the only evidence used to condemn a saddle, rider, or horse.

Example of Appropriate Use

An 11-year-old barrel racing mare has intermittent right hind performance issues. She is not dramatically lame on a straight line, but she feels weaker in turns and is less willing to push out of the hind end.

Thermography shows repeatable increased heat around the right hock region when scanned under controlled conditions.

That does not diagnose the problem.

What it does is help guide the next step.

A vet then performs a full lameness exam, palpation, flexion testing, gait assessment on straight lines and circles, and targeted imaging. If ultrasound or radiographs confirm a specific hock, suspensory, or soft tissue problem, treatment and rehabilitation can be planned properly.

That is good use of thermography.

The scan raised a useful question. The veterinary workup answered it.

How Can Owners Avoid Wasted Money?

Before paying for thermography, ask:

• Who is performing the scan?

• Who is interpreting it?

• Is a veterinarian involved?

• What training does the person have?

• What camera is being used?

• Are the conditions controlled?

• Will the horse be clean, dry, and free of topical products?

• Will both sides be compared?

• Will the report clearly separate thermal findings from clinical diagnosis?

• What happens if the scan is abnormal?

• What diagnostics may still be needed?

A good provider should be comfortable saying:

Thermography may help, but it does not replace a vet exam.

That sentence is not a weakness. It is the sign of someone who understands the tool.

Prevention and Monitoring: Where Thermography May Fit

Thermography may be useful as part of a broader monitoring plan for performance horses, but it should not be the only monitoring tool.

A sensible monitoring plan may include:

• Regular veterinary checks

• Farrier care

• Hoof balance monitoring

• Saddle fit checks

• Training load records

• Recovery tracking

• Limb palpation after work

• Early investigation of heat, swelling, or lameness

• Gait video comparison over time

• Ultrasound follow-up for known soft tissue injuries

• Thermography as an adjunct where appropriate

The strongest prevention tool is still daily observation by someone who knows the horse.

A scan is useful. A good horse person noticing that the left hind fills after harder work is also useful. Ideally, you use both.

Myth vs Reality

Myth	Reality
Thermography diagnoses lameness.	It detects surface temperature patterns that may guide further investigation.
A red area means injury.	Heat can come from inflammation, pressure, exercise, environment, or artefact.
A normal scan rules out disease.	Deep, structural, or neurological problems may not show clearly on thermography.
Anyone with a thermal camera can diagnose a horse.	Interpretation should involve a trained veterinarian and proper clinical context.
Thermography can diagnose EPM.	EPM requires neurological examination, appropriate testing, and ruling out other neurological diseases.
Phone thermal cameras are good enough.	AAT guidelines state phone add-on thermal imagers are not adequate for medical thermology imaging.

FAQs About Infrared Thermography in Horses

Is thermography safe for horses?

Yes. Thermography is noninvasive and does not use ionising radiation. The horse is imaged from the outside, and sedation is not usually needed just for the scan. The safety issue is not the camera. The safety issue is misinterpretation.

Can thermography find a tendon injury?

It may show increased surface heat over a region associated with tendon inflammation, especially if the injury is superficial. It cannot confirm tendon fibre damage or lesion size. Ultrasound or MRI is usually needed to assess tendon structure.

Can thermography diagnose back pain?

It can show heat asymmetry or thermal patterns over the back that may support further investigation. It cannot prove the exact cause of back pain by itself. Saddle fit, ridden assessment, palpation, lameness workup, radiographs, ultrasound, or other diagnostics may be needed.

Can thermography diagnose EPM?

No. EPM is a neurological disease. Diagnosis requires neurological examination, serum and/or cerebrospinal fluid antibody testing, and ruling out other neurological conditions. (MSD Veterinary Manual)

Should I get thermography before a lameness exam?

Usually, the best first step is a veterinary lameness exam. Thermography may be useful as an adjunct, especially in subtle or complex cases, but it should not delay proper hands-on assessment when the horse is lame, painful, swollen, or unsafe.

The Bottom Line

Infrared thermography can be useful in equine lameness cases, but only when it is used honestly.

It can show abnormal heat patterns.

It can help compare left and right sides.

It can support saddle fit, rehabilitation, soft tissue, and performance investigations.

It can help guide the next diagnostic step.

But it cannot diagnose most lameness causes by itself. It cannot replace a veterinary exam. It cannot prove EPM, fractures, tendon tears, joint infection, or deep structural disease.

The best use of thermography is not as a shortcut. It is as one more piece of clinical evidence in a proper lameness workup.

A colourful image can be helpful. A correct diagnosis is better.

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If your horse is lame, sore, or has an abnormal thermography result and you are unsure what it means, ASK A VET™ can help you organise the signs, understand the urgency, and decide when hands-on veterinary assessment is needed.