Lecture 2: Equine Lameness Examination

What needs to be asked during the history section of an equine lameness exam?

• signalment, use of horse

• duration of lameness, worse or improved w/ time or circumstance, which leg

• gradual vs acute onset, hx of trauma, management changes

• medications

• past lameness hx

• when last trimmed or shod by farrier

What is usually performed during a PE for a lameness exam?

• quick TPR

• observe: conformation, swellings, how horse is standing, hoof care, muscle symmetry

• limb palpation: joints for effusion and ROM, tendons/ligaments, digital pulses

What are you palpating for on a limb during a lameness exam?

• effusion

• edema

• bony proliferation

What two joints are being indicated here?

arrow: femoropatellar

circle: medial femorotibial joint

What is the arrow showing?

pitting

What are you palpating for on tendons and ligaments?

• enlargement

• thickening

• pain

True or false: every horse should have digital pulses.

true: every horse should have a faint digital pulse → increase in ability to palpate are significant

What is the most appropriate conclusion to make from palpating increased digital pulses?

the horse has inflammation in the foot

Back pain can be a primary source of pain, but is often secondary to what other injury?

hock pain / hind limb lameness

What diagnostic test must be done BEFORE blocking the horse during a lameness exam?

hoof testing

What are the movements for a horse during a basic lameness exam?

• walking in a straight line

• trotting in a straight line

• trotting in a circle (both directions) - hard and soft surface

What are the movements for a horse during a advanced lameness exam?

• canter

• under saddle

Describe the gait evaluation during a walk.

• 4 beat gait - each foot hits the ground separately

• evaluate stride length

• tracking up? (hind foot lands in same spot front foot left)

Describe the gait evaluation during a trot.

• 2 beat gait

• limbs move in diagonal pairs

• BEST gait for seeing lameness

What are the levels of the AAEP lameness grading scale?

0: Lameness not perceptible under any circumstances.

1: Lameness is difficult to observe and is not consistently apparent, regardless of circumstances

2: Lameness is difficult to observe at a walk or when trotting in a straight line but consistently apparent under certain circumstances

3: Lameness is consistently observable at a trot under all circumstances.

4: Lameness is obvious at a walk.

5: Lameness produces minimal weight bearing in motion and/or at rest or a complete inability to move.

How can you determine a sound limb from a lame limb?

sound limb

• drops fetlock

• head nod - head moves DOWN when horse bears more weight

lame limb

• head bob - head moves UP when lame leg hits ground

• hip hike - hind limb lameness, increased pelvic movement

• asymmetrical movement - shorter stride

Why are flexion tests done during a lameness exam?

to put stress on a joint to see if it changes the horse’s lameness

How can lameness be localized?

nerve blocks: local anesthetic injected SQ over nerves

What are the basic blocking principles?

• nerve blocks: start distal and work proximal

• local anesthetic migrates so wait 5 min, use the least volume possible, and make sure your location is accurate to get accurate results

What are the three commonly used local anesthetics for blocks during a lameness exam?

• mepivicaine (less tissue irritation)

• lidocaine (stings)

• bupivicaine

Where is a palmar digital nerve block given?

insert needle over neurovascular bundle proximal to the collateral cartilages

What structures are blocked by the palmar digital nerve block?

• caudal 1/3 of the foot

• sole

• navicular apparatus

What is blocked by the abaxial sesamoid block?

all strucutes below fetlock, ± the fetlock itself

Where is the abaxial sesamoid block given?

insert needle SQ over the neurovascular bundle at the abaxial surface of the sesamoid bones

What structures are blocked by the low 4 point block?

• fetlock joint and distal

• inconsistent loss of skin sensation dorsally on hind limb

Where is the block given for a low 4 point block?

• inject under the button of the splint bone (medial and lateral)

• inject over the neurovascular bundle between the DDF and the suspensory ligament