Diagnosing Lamness Flashcards
When performing a pre-purchase lameness evaluation, what party are you working for?
Buyer
What are the 7 classic steps of a lamenss exam?
History PE Palpation Observation a exercise Flexion tests Diagnostic nerve blocks Diagnostic imaging
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?
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
T/F: when evaluating lameness, you want to palpate the limb both weight bearing, and non-weight bearing
True
What is the gait lameness is graded from?
Trot
What is the best surface for evaluation of lameness?
Firm and event
For more subtle lameness, may require different surfaces, hills/incline
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
T/F: in hindlimb lameness the the head bob is down on the sound limb
False
Head goes down on the LAME limb
When using hoof testers, they are placed on all the following except?
Wall Heels Coronary band Frog Sole
Coronary band
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”
Grade this lameness..
Difficult to observe
Inconsistent at any gait
Grade 1
Grade this lameness..
Difficult to observe in a straight line but consistently apparent under certain circumstances (eg circling, hard surface, or incline)
Grade 2
Grade the lameness..
Consistently observable at a trot under all circumstances
Grade 3
Grade the lameness…
Obvious lameness with marked head nod, hitching, and shortened stride
Grade 4
Grade this lameness..
Minimal weight bearing/non-weight bearing and inability to move
Grade 5
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
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
