Diagnosing Lameness in the Horse Flashcards
What is the definition of lameness?
Alteratiion of the normal gait pattern caused by a functional or structural disorder in the locomotor system.
What is lameness usually due to?
PAIN!
What can be 3 general forms of lameness?
Neurologic
Metabolic
Mechanical
When performing a pre-purchase exam, who do you work for?
Buyer
What are the 7 classic steps of a lameness exam?
History PE Palpation Observation at exercise Flexion tests Diagnostic nerve blocks Diagnostic imaging
What is the primary goal of a lameness exam?
Localization and diagnosis.
When trying to determine duration of the lameness, what is a better question to ask the owner?
When was the horse last normal?
What are you looking for on the distance portion of a lameness exam?
Symmetry
What are you looking for on the close-up portion of a lameness exam?
Symmetry
What is a good thing to do to help establish normals?
Looks at the contralateral limb.
What should you do with EVERY lameness you see?
Put hoof testers on it.
What are 2 things you are assessing when observing stride?
Length of stride
Foot placement
What are 6 things to watch for when observing at exercise?
Stride Foot flight arc Path of the foot flight Foot strike Joint angles Gluteal excursion
What gait is lameness graded at?
At a trot
What is the best surface for a lameness exam?
Firm and even
NOTE: You may need different surfaces, hills etc.
“Down on the sound” means..?
The head will bob down when the horse is landing on the normal/sound front limb. Conversely it will come up on the lam front limb.
What are you watching for mostly when assessing the hind end of lameness?
A “hip hike” or increased gluteal excursion.
What structure should you never put your hoof testers on?
The coronary band.
What is a Grade 1 lameness on the AAEP Lameness scale?
Difficult to observe, inconsistent
What is a Grade 2 lameness on the AAEP Lameness scale?
Difficult to see in a straight line, but consistently seen under certain circumstances.
What is a Grade 3 lameness on the AAEP Lameness scale?
Consistently seen at a trot under all circumstances.
What is a Grade 4 lameness on the AAEP Lameness scale?
Obvious with marked head nod, hitching and shortened stride.
What is a Grade 5 lameness on the AAEP Lameness scale?
Minimal/non-weight bearing. Can’t move.
What are 5 pathognomonic lameness’ diagnose at the walk?
Peronius tertius rupture Upward fixation of the patella Stringhalt Fibrotic myopathy Sweeny
What will you see in a peroneus tertius rupture?
Can extend the hock while the stifle is flexed, and you may see an “S” curve below the SMST (this is the ruptured muscle, ouchie!)
What is stringhalt?
Hyperflexion of the hind limb.
What is fibrotic myopathy?
Fibrosus of the SMST
What is Sweeny?
Nerve damage resulting in the atrophy of the supra-and infraspinatus muscles.
When do you perform your flexion tests?
AFTER palpation, observation at exercise and using hoof testers.
What is a positive flexion test?
Exacerbated lameness.
How do you perform a flexion test?
Flex the joint of interest and trot off in a straight line immediately after.
When performing a flexion test on a distal forelimb, which joint are you flexing and for how long?
Just trying to flex at the carpus for 30 seconds.
When performing a flexion test on the proximal forelimb, which joint are you flexing and for how long?
Carpal joint for 60 seconds.
NOTE: You end up flexing the carpus, elbow and shoulder.
When performing a flexion test on a distal hindlimb, which joint are you flexing and for how long?
Just trying to flex at the carpus for 30 seconds.
When performing a flexion test on the proximal hindlimb, which joint are you flexing and for how long?
The hock, stifle and hip for 90 seconds.
NOTE: This test is NOT hock specific.
Why do you perform nerve blocks?
To localize the lameness.
When performing nerve blocks, where do you begin?
Distally and work proximally.
When performing nerve blocks, why do you not want to use sedation?
Sedation makes it more challenging to watch them go.
NOTE: If they’re being jerks, you can use a little Ace.
What 4 different methods can you use when performing nerve blocks?
Perineural (nerve block)
Regional
Direct infiltration (ie. if you have a big mass)
Intraarticular
What is a reason NOT to perform a nerve block?
Severe lameness.
What agents might you use in a nerve block?
Lidocaine
Mepivacaine
Bupivacaine
What kind of volume should you use with perineural anesthesia?
The smallest volume possible
When doing a skin test (to test your nerve block), what do you use first?
A blunt instrument.
From distal to proximal, what 6 nerve blocks can you perform?
Palmar digital Basi-sesamoid Abaxial sesamoid Low and high 4 point MUN (forelimb) Peroneal/tibial (hindlimb)
What at the landmarks for the palmar digital nerve block?
Groove between the flexors and the ergot medially and laterally.
What does the palmar digital nerve block anesthetize?
Essentially the whole foot.
What are 3 main reasons why the palmar digital nerve block might fail?
Adhesions between the navicular bone and the DDFT
Osteoarthritis
Improper/incomplete anesthesia
What 6 structures does the abaxial (basisesamoid) nerve block anesthetize?
Foot, P2 Distopalmar P1 Proxiaml and distal interphalangeal joints Distal SDFT and DDFT Distal sesamoidean ligament Distal annular ligament
What nerves does the low 4-point block?
Lateral and medial palmar metacarpal nerve
Lateral and medial palmar nerve
What volume should you use in the low 4-point block?
3mL per palmar nerve and 1mL per palmar metacarpal nerve
What structures does the low 4-point block?
Everything from the fetlock down.
What risk is there when using a high 4-point?
Could enter synovial structures.
What block can you used instead of a high 4-point?
Lateral palmar nerve block
What structures are anesthetized with a high 4-point block?
Suspensory ligament
Some flexor tendons
Some of metacarpal III and metacarpal IV
What does the lateral palmar nerve block block?
The origin of the suspensory ligament.
If you’re doing joint blocks, can you start high and go low?
Yes, because it should be intraarticular.
