Approach to Equine Lameness Investigation

Question 1

How would you identify lameness on the forelimb?

Answer 1

Head lifts when lame limb is weight bearing

Question 2

How would you identify lameness on the hindlimb?

Answer 2

asymmetric movement of the pelvis, often described as a ‘hip-hike’
* shortened stride length
* fetlock drop

Question 3

What does ipsilateral forelimb lameness in trot look like?

Answer 3

Lame hind leg hits the ground:
* Horse shifts its weight forward to transfer load away from lame limb
* Contralateral forelimb bears weight simultaneously with the lame hind limb
* Head nod coincides
* Thus mimicking lameness in the forelimb ipsilateral to the lame hindlimb.

Question 4

What would you do for diagnostic analgesia?

Answer 4

Encompasses perineural analgesia and intra-synovial analgesia
* Local anaesthetic inhibits nociceptive nerve conduction
* If injected perineurally; desensitizes structures distal to block
* Ideally begin investigation distally and work proximally
* Identify region that is the source of the pain > guide imaging

Question 5

How would you interprate diagnostic analgesia?

Answer 5

• Assess whether the block is positive or negative
• Specific duration of time is recommended for re-examination following the block

Question 6

What are some potential complications with equine lameness?

Answer 6

Soft tissue swelling
* Haematoma/bruising
* Infection
* Skin
* Joint or other synovial structure (emergency)
* Synovitis (aseptic flare)
* Cardiovascular effects if intravascular injection of LA?

Question 7

What are some potential contradindications of lameness?

Answer 7

Suspected fracture
* Skin infection/dermatitis of injection site
* Moderate – severe soft tissue injury
* (Typically signs are obvious enough that DA is not warranted)

Question 8

What is the site of the palmar/ Plantar digital nerve block?

Answer 8

Just proximal to collateral cartilage, abaxial to the edge of the tendon, medial and lateral aspects

Question 9

What is the abaxial sesamoid nerve block site?

Answer 9

immediately palmar to the enurovascular bundle at the abaxial surface of the proximal sesamoid bones
medial and lateral aspects

Question 10

What are the two sites for the low 4 point nerve block?

Answer 10

• Palmar metacarpal nerves
• Palmar nerves

Question 11

What structures are desensitised in the low 4 point nerve block?

Answer 11

• Fetlock joint
• Proximal sesamoid bones
• Distal medial and lateral branches of the suspensory ligament
• Flexor tendons distal to block
• Digital flexor tendon sheath
• Entire distal limb

Question 12

What is the distal interphalangeal (coffin) joint block?

Answer 12

Limb weight-bearing, on dorsal midline, insert the needle immeditaely proximal to the coronary band

Question 13

What structures are desensitised in the DIP joint block?

Answer 13

• DIP joint
• Collateral ligaments
• Navicular bone
• Toe region of the sole
• Diffusion of local anaesthetic between DIP joint and navicular bursa after 15 minutes

Question 14

What is the site of the collateral sesamoidean ligament approach (Fetlock Joint)

Answer 14

• Proximal palmar process of P1
• Dorsal aspect of the proximal sesamoid bone
• Palmar condyle of MCIII

Question 15

What is the tarsometatarsal joint block?

Answer 15

Used to diagnose OA in the small tarsal joints