Diagnosing Lamness Flashcards by Colin Proctor

When performing a pre-purchase lameness evaluation, what party are you working for?

Buyer

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What are the 7 classic steps of a lamenss exam?

History 
PE 
Palpation 
Observation a exercise 
Flexion tests 
Diagnostic nerve blocks 
Diagnostic imaging

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What are important questions to ask in a history for a lameness exam?

Signalment ?
Work? 
Shoeing history?
Previous lameness?
Duration of lameness? (Last normal?)
What as been done since lameness noted (Rest? Work?) 
Possible cause?
Does horse warm into or out the the lameness? 
Stumbling ?
Treatments?

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When doing a PE, you are unsure if the limb appears abnormal. How can you evaluate visual abnormalities?

Compare to contralateral limb

Conformation
Swelling
Symmetry

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T/F: when evaluating lameness, you want to palpate the limb both weight bearing, and non-weight bearing

True

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What is the gait lameness is graded from?

Trot

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What is the best surface for evaluation of lameness?

Firm and event

For more subtle lameness, may require different surfaces, hills/incline

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T/F: in a lameness exam, the lameness appears to be in the forelimbs. The horse has a head drop when the right limb in down. This means the lameness is in the right limb?

False

“Down sound”

If head goes down on the right limb, then the right limb is sound. The left limb would be lame

Head rises to decrease weight on lame limb

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T/F: in hindlimb lameness the the head bob is down on the sound limb

False

Head goes down on the LAME limb

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When using hoof testers, they are placed on all the following except?

Wall 
Heels 
Coronary band 
Frog 
Sole

Coronary band

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A horse presents to you with a grade 3/5 RF lameness, which of the following would be expected as you watch the horse in motion?

A. Head nod down when RF is in contact with the ground

B. Head nod down when the LF is in contact with he ground

B. Head not down when LF is in contact with the ground

“Down sound”

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Grade this lameness..

Difficult to observe
Inconsistent at any gait

Grade 1

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Grade this lameness..

Difficult to observe in a straight line but consistently apparent under certain circumstances (eg circling, hard surface, or incline)

Grade 2

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Grade the lameness..

Consistently observable at a trot under all circumstances

Grade 3

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Grade the lameness…

Obvious lameness with marked head nod, hitching, and shortened stride

Grade 4

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Grade this lameness..

Minimal weight bearing/non-weight bearing and inability to move

Grade 5

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What are 5 pathogomonic lamenesses that can be diagnosed at the walk?

Peroneus tertius rupture 
Upward fixation of the patella (locking patella) 
Stringhalt 
Fibrotic myopathy 
Sweeney

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What is causing this lameness..

Tarsus falls forward in hyperextention.
Limb lags behind in forward stride

Peroneus tertius rupture

When limb is pulled in to hyperextention, normall the hock would be held in flexion

With ruputre, limb is fully extended

What is causing this lameness.. ?

Hindlimb is held in extension, stifle and digits
Horse lags hindlimb behind
On flexion, abrupt sticky movement .

Upward fixation of the patella

For stay apparatus, patella hooks over the medial trochlear ridge, holding the stifle in extension

And because of reciprocal apparatus the hock is held in extension

What is this lameness?

Shortened cranial stride
Unsymmetrical appearance of of the muscles of hindlimb.

Fibrotic myopathy

What is the lameness..

Exaggerated flexion of the hind limb, but fluid in motion

Springhalt

Can be confused with uppward fixation of the patella, but this is more choppy

What is the lameness..

Shortened cranial stride in the forelimb. Muscle atrophy over the scapula

Sweeney — suprascapular nerve injury

How is a flexion test preformed?

Forelimb:
Distal: Hold distal limb in flexion for 30sec
Carpal: hold proximal limb in flexion for 60sec
Trot off in a straight line immediately after flexion

Hindlimb:
Distal: same as forelimb
Proximal limb: spavin test (90sec), not hock specific

Positive test = exacerbated lameness

What is the criteria for local anesthesia for lameness localization?

Is the horse lame enough to tell the difference

Too lame —> blocking can lead to catastrophic failure

Will the horse stand for a block?

What are the methods of local anesthesia?

Perineural (nerve block) Regional Direct infiltration of site IA

What agents are used in local anesthesia?

Duration 30mins -2hrs : 2% lidocaine 2% mepivacaine (carbocations) Duration 5-6hrs: 0.5% bupivacaine (Not for diagnostics)

T/F: perineural anesthesia can be tested by testing sensation of the skin with a dull instrument, presence of sensation means failure of the nerve block

False - first sensation lost, first one back

What are the specific nerve blocks form distal to proximal?

Palmar digital (PD) Basi-seasamoid /abaxial seasmoid Low and high 4 point block — block lat/med palmar and palmar metacarpal nerves

Where do you place your needle for and palmar digital nerve block?

Groove between flexors and ergot (med and lateral) 1.5ml per site, should see effect in 5 ins

You just did a palmar nerve block.. what structures are anesthetized?

``` Sole Navicular apparatus Soft tissue of heel Coffin joint Digital portion of DDFT ```

What are reasons for failure of a palmar digital nerve block?

Adhesions between navicular bone and DDFT OA of coffin Accessory nerve supply for dorsal digital branches Concurrent proximal dz Improper/incomplete anesthesia

Where do you place your needle for an abaxial nerve block?

At the abaxial border of each proximal seasmoid bone, palpate neurovascular bundle

What structures are anesthetized following an abaxial nerve block?

Foot, P2 Distopalmar P1 Proximal and distal interphalangeal joint Distal SDFT and DDFT Distal seasmoidean ligament Digital annular ligament

What nerves are blocked in a low 4point nerve block?

L/M palmar metacarpal | L/M palmar

What are the locations for needle placement in a low 4 point nerve block?

Between palmar MC II and MC II and IV Between SL and DDFT

What structures anesthetized in a low 4 point block?

Everything from fetlock down

What nerve block will block the origin of the suspensory ligament?

Lateral palmar nerve bock Needle enters in mediolateral direction, distal 1/3 of groove along medial aspect of accessory carpal bone

What structures are anesthetized in a high 4 point nerve block?

Suspensory lig Some flexor tendons Some MCII and MC IV

What is the minimum number of view required for radiographs of a limb?

4 2 oblique views 1 lateral 1DP

What is the only imaging modality that can provide realtime evaluation of soft tissues and bone?

Ultrasound

How do you do intrarticular anesthesia?

STERILE Insert needle w/o syringe Collect synovial fluid prior to injection Inject volume of anesthetic > volume of fluid collected —> slightly distend joint and add a small amount of antibiotic to joint

What are the indications for nuclear scintigraphy?

If lameness site cannot be determined Localized lameness but not detectable with radiographs or U/s Multiple limb lameness Intermittent lameness Upper limb/pelvic lameness Suspect a fracture but not seen on rads

What is the modality of choice for imaging bone?

CT Can accurately delineate osseous lesions Eliminate superimposition

What is the best method of imaging soft tissues?

MRI — can be used when lameness cannot be detected with US or rads