Equine Lameness Investigation

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Questions and Answers

What is the primary goal of performing diagnostic analgesia in lameness investigation?

To guide further imaging based on pain source (correct)

To assess the efficacy of different local anaesthetics

To desensitize structures distal to the injection site

To completely eliminate pain before treatment

Which local anaesthetic is described as having the fastest onset and can irritate the skin?

Lidocaine (correct)

Bupivicaine

Mepivicaine

Procaine

When evaluating the success of a diagnostic analgesia procedure, what indicates a positive response?

A minimum of 50% improvement in lameness (correct)

Less than 50% improvement in lameness

No visible improvement in lameness

Complete abolition of lameness

Which sequence is recommended for the investigation of lameness using diagnostic analgesia?

Begin distally and work proximally Signup and view all the answers

Which local anaesthetic is noted for being the least irritating to the skin?

Mepivicaine Signup and view all the answers

What is the generally recommended duration for re-examination following a nerve block?

Generally ~10 minutes Signup and view all the answers

What complications may arise from administering local anaesthesia?

Soft tissue swelling and infection Signup and view all the answers

Which method should be used to ensure sterile preparation for intra-synovial analgesia?

Scrubbing with antiseptic for at least 5 minutes Signup and view all the answers

What is a common result of injecting local anaesthetic too soon after placement?

Insufficient time for the block to work Signup and view all the answers

What is a critical consideration when performing perineural analgesia?

Employing clean technique and proper restraint Signup and view all the answers

What indicates a 'head nod' when assessing lameness?

The horse lifts its head when the lame limb is weight bearing Signup and view all the answers

Which of the following describes a common sign of hindlimb lameness?

Asymmetric movement of the pelvis Signup and view all the answers

What occurs during flexion tests for forelimbs?

Carpal flexion or distal limb flexion is checked Signup and view all the answers

In the European Lameness Grading Scale, what does a score of 5 indicate?

Severe lameness Signup and view all the answers

What does a positive flexion test indicate?

Increased pain associated with the joints Signup and view all the answers

What is a key characteristic of bilateral lameness?

Shortened or choppy stride length Signup and view all the answers

How can severe hindlimb lameness be mistaken for forelimb lameness?

Contralateral forelimb assumes more weight Signup and view all the answers

What describes a subtle sign of mild lameness in a horse?

A subtle head nod is observed when the lame forelimb strikes Signup and view all the answers

What is the first step when approaching a lame horse?

Conduct a detailed history evaluation Signup and view all the answers

Which of the following factors should be included in the history taking of a lame horse?

Recent changes in exercise or surface Signup and view all the answers

What does palpation focus on during a lameness evaluation?

Assessing heat, pain, and swelling Signup and view all the answers

During a gait evaluation, which assessment can help determine the lameness severity?

Flexion tests on affected limbs Signup and view all the answers

Why is it important to observe the horse walk in a straight line during a lameness evaluation?

To identify irregularities in limb movement Signup and view all the answers

How does the surface on which the horse is lunged affect the assessment of lameness?

Hard surfaces can worsen bone injuries and foot lameness Signup and view all the answers

In examining the horse, what does a faulty conformation indicate?

Potential risk for future injuries Signup and view all the answers

What is the main purpose of incorporating nerve and joint blocks in a lameness investigation?

To identify the specific area of pain or lameness Signup and view all the answers

What is the appropriate needle size and length for a Tarsometatarsal joint block?

20 gauge 1” Signup and view all the answers

Which of the following is a common reason for performing a Tarsometatarsal joint block?

Diagnosis of OA of the small tarsal joints Signup and view all the answers

What approach is used for a Digital Flexor Tendon Sheath block?

Palmar axial sesamoidean approach Signup and view all the answers

How far should the needle be inserted for the deep branch of the lateral plantar nerve block?

15mm distal to lateral splint bone Signup and view all the answers

What amount of local anesthetic is typically used for the deep branch of the lateral plantar nerve block?

3ml Signup and view all the answers

What is a critical outcome to assess after performing a deep branch of the lateral plantar nerve block?

Resentment to digital palpation Signup and view all the answers

Which joint compartments should be blocked to ensure proper diffusion of local anesthetic into the stifle?

Medial femorotibial, lateral femorotibial, and femoropatellar Signup and view all the answers

Which option describes the technique of performing a Tarsometatarsal joint block?

Needle inserted parallel to the ground in a dorsomedial direction Signup and view all the answers

Which of the following is a contraindication for performing perineural analgesia?

Skin infection of injection site Signup and view all the answers

What is the main nerve blocked in a palmar digital nerve block?

Medial and lateral palmar nerves Signup and view all the answers

What structures are desensitized by the abaxial sesamoid nerve block?

Entire foot and middle phalanx Signup and view all the answers

During a low 4-point nerve block, which anatomical landmarks are primarily used?

Palmar metacarpal nerves Signup and view all the answers

What is the correct needle size for performing an abaxial sesamoid nerve block?

25 gauge 5/8 inch Signup and view all the answers

Which structure may be desensitized if the palmar digital nerve block is effective?

Distal interphalangeal joint Signup and view all the answers

In a distal limb perineural analgesia, which block is used for desensitizing the fetlock joint?

Low 4-point nerve block Signup and view all the answers

What is the volume of local anesthetic typically used for a palmar digital nerve block?

1.5-2 ml Signup and view all the answers

Which location is NOT a site for intra-synovial diagnostic analgesia?

Coxofemoral joint Signup and view all the answers

What is a risk when placing a low 4-point nerve block too high?

Desensitization of proximal structures Signup and view all the answers

Which structure is NOT desensitized during a distal interphalangeal joint block?

Palmar digital nerves Signup and view all the answers

What is the purpose of rechecking the site after administering a palmar digital nerve block?

To assess skin sensitivity and effectiveness Signup and view all the answers

In which block is the needle inserted just proximal to the coronary band?

Distal interphalangeal joint block Signup and view all the answers

Study Notes

Approach to Equine Lameness Investigation

The presentation covers a comprehensive approach to investigating lameness in horses.
Key learning objectives include understanding how to approach a lame horse, describing lameness evaluation, and identifying the use and description of nerve and joint blocks.

History

Signalment (breed, age, sex) is crucial.
The horse's use and competition level provide context.
The perceived problem is vital, as is the onset, duration, and progression of the lameness.
Previous history, trauma, and medication use are relevant factors.
Changes in management and farriery practices are also important details.
The effects of exercise or surface type should be considered.

Clinical Examination

Observation of obvious clinical signs, posture, conformation, and symmetry is important.
Faulty conformation is a warning sign, not an unsoundness.
Palpation, assessing for heat, pain, swelling, effusion, and range of motion, is essential.
A hoof tester examination is a useful diagnostic tool.

Gait Evaluation

Gait evaluation involves observing the horse's walk (straight line), trot (straight line), and lunge (in a circle on both soft and hard surfaces).
Assessing lameness on inside/outside of circle during lunge is important.
Evaluating lameness through flexion tests and a ridden assessment further helps clarify the diagnosis.

Identifying Lameness

Lameness is assessed at the walk and trot, looking for distinguishing signs.
Forelimb lameness might manifest as a head nod or the horse putting less weight on the affected limb.
Hindlimb lameness can sometimes be identified by an asymmetrical movement of the pelvis ('hip hike' or 'hip drop').
Gait evaluation during lunging on both soft and hard surfaces is crucial for a thorough diagnosis.
Flexion tests and a ridden assessment provide more detailed insights into the nature of the lameness.

Identifying Lameness Continued

Assessing lameness during lunging can provide a better understanding of the specific movement causing the issue.
Determining if the lameness is worse on hard or soft surfaces helps differentiate between bone and soft tissue issues.
Flexion tests, identifying pain on specific limb movements, are critical diagnostic procedures.
The ridden assessment is a final diagnostic input.

Referred Lameness

Severe hindlimb lameness can sometimes be mistakenly diagnosed as forelimb lameness.
The horse adapts its weight distribution, mimicking forelimb lameness in its gait.
Differential diagnostics, including diagnostic analgesia, are necessary to correctly determine the source of the lameness.

Grading Lameness

The European Lameness Grading Scale (0-10) provides a standardized method to quantify lameness severity observed during a trot.
Gradations from sound (0) to severe (7-10) based on consistent observation of subtle or marked head/pelvic asymmetry, gait characteristics, and response to specific movements.
An additional alternative Grading Scale (0-5) defines lameness by factors such as difficulty observing lameness during a walk/trot, gait abnormalities, consistency, and marked movements.

Inertial Measurement Units

Inertial Measurement Units (IMUs) are increasingly used in equine lameness assessment, objectively measuring head and pelvic movements to quantify the extent of lameness.
Although helpful, IMUs are not a replacement for a skilled equine practitioner.

Principles of a Lameness Investigation

The investigation process, including consistent lameness assessment, diagnostic analgesia, diagnosis, and treatment are interwoven.
Performing these combined factors is crucial for an effective and thorough equine lameness assessment.

Diagnostic Analgesia

Local anesthetics, including lidocaine, mepivacaine, and bupivacaine, are used to desensitize nerves and block pain signals to pinpoint the painful area.
The process begins distally and moves proximally through affected areas to accurately identify the source of the pain and aid in imaging directions by the examiner.

Interpreting Diagnostic Analgesia

Determining if the block worked. Assessing skin sensation, and observing the horse's gait for signs of lameness relief are essential. Assessing any degree of lameness reduction following the block, from 50% to over 75%, is crucial.
Specific time duration for re-evaluation after a lameness block is important.
The re-evaluation criteria assist in a more accurate diagnosis.

Preparation for Diagnostic Analgesia

Thorough preparation is necessary. Adequate restraint, operator safety measures (equipment, like hard hats and sedation tools, short-acting sedation), and clean technique are essential.

Complications and Contraindications

Potential complications include soft tissue swelling, hematomas, and infections that could be caused by the procedure itself.
The presence of skin infections, suspected fractures, and moderate-severe tissue injuries are contraindications to diagnostic analgesia.

Perineural Analgesia

Several specific nerve blocks, including palmar digital, pastern ring, abaxial sesamoid, and low 4-point, are used in the forelimb and hindlimb.

Intra-Synovial Diagnostic Analgesia

Distal limb, involving joints like the distal interphalangeal, navicular bursa, and metacarpophalangeal, are treated with this technique.
Upper forelimb and hindlimb areas are similar targets.

Palmar/Plantar Digital Nerve Block

The site of this block is just proximal to the collateral cartilage, abaxially to the tendon.
The palpation and injection technique include detailed steps and precautions.

Abaxial Sesamoid Nerve Block

The site of this block is immediately palmar to the neurovascular bundle at the proximal sesamoid bones.
Specific techniques for vein artery nerve identification and injection volume are outlined.

Low 4-Point Nerve Block

The site is distal to the splint bone between the suspensory ligament and the deep digital flexor tendon.
The procedure, detailed technique, and care for placement near the deep digital flexor tendon sheath are discussed.

Distal Limb Perineural Analgesia Summary

Overview of the three procedures: Abaxial sesamoid nerve block, low 4-point nerve block, and palmar digital nerve block.

Distal Interphalangeal (Coffin) Joint Block

Procedure involves injection of local anesthetic targeting the collateral ligaments of the DIP (distal interphalangeal) joint.
It emphasizes the appropriate placement of the needle.

Navicular Bursa Block

Correct radiographic alignment of the needle is crucial for effective treatment of navicular spurs.
Specific steps and considerations during this procedure are emphasized.

MCP/MTP (Fetlock) Joint Block

Three described approaches are available for the fetlock joint block.
Specific steps and considerations are emphasized.

Fetlock Joint Block: Collateral Sesamoidean Ligament Approach

Detailed descriptions of anatomical boundaries, targeting the proximal palmar process of P1, are given.
Specific directions for inserting the needle along the dorsal aspect and parallel to the ground are outlined.

Tarsometatarsal (TMT) Joint Block

Considerations for diagnosing Osteoarthritis (OA) of the tarsal joints are discussed.
Potential communication with the distal intertarsal joint is a factor in some cases.

Digital Flexor Tendon Sheath Block

Different approaches are described, including approaches targeting the proximal and distal sections of the tendon sheath, and variations in placement.

Deep Branch of the Lateral Plantar Nerve Block

The lateral approach technique, needle insertion technique, and appropriate volume of local anesthetic are detailed.

Stifle

The diffusion of local anesthetic between the three joint compartments is emphasized.
The necessity of specific blocking the three joint compartments is highlighted because diffusion is variable.
The method of blocking the three compartments is also noted.

Useful Resources and Further Reading

A list of relevant, credible resources in the field is presented (books, websites).

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Description

This quiz focuses on a systematic approach to investigating lameness in horses. It covers essential aspects such as signalment, clinical examination, and the use of nerve and joint blocks in evaluation. Participants will learn how to effectively assess and understand different factors influencing equine lameness.