Examination of the Lame Horse Flashcards
Important questions to resolve when working up a lame horse?
Is the horse actually lame?
How many limbs affected?
Which limb(s) affected?
Does it matter:
- to the owner (performance)?
- to the horse (welfare)?
What questions should we ask to gain a history in a lameness case?
BIOP?
Use of the horse (discipline and level)?
Duration of lameness?
Progression of lameness?
Any treatments given so far?
On any meds currently?
When are they lame/when noticed?
- ridden/lunge/in hand?
Any recent trauma?
Management:
- recent/current work regimen?
- housing and feeding?
- farrier/physio?
– who/when/usual frequency?
- any changes?
Any problems?
Lameness severity?
What is the current situation?
General clinical exam of lame horse?
Brief cardiorespiratory exam.
Pain score?
BCS?
Stand back:
- conformation.
- posture and loading.
- symmetry.
- lumps and bumps?
Thorough inspection and palpation of the lame horse?
Palpate limbs.
- over bones, muscles, tendons and joints.
Palpate digital pulses.
Aiming to identify:
- abnormalities.
- asymmetry between limbs.
- range of movement.
- painful response.
Palpate spine.
- given the appendicular skeleton is linked to the spine.
– lameness may manifest as back pain and back pain may manifest as lameness.
- palpate the DSPs and epaxial musculature.
- assess movement away from pressure points.
Hoof testers.
- essential for eery foot lameness and acute lameness.
- use systematically serially around circumference, then frog and inside/outside heels then across both heels.
– use digital pulses to determine pain levels and start where less painful.
- look for reaction:
– withdrawal of limb.
– ears back.
– turn to bite you!
Gait evaluation - straight line at walk and trot.
To identify lameness, look for:
- head nod.
- hip hike.
- change in phase of stride length.
- flight arc (height above ground).
- flight path (med/lat).
– plaiting if bilateral.
- foot placement.
– should be flat.
– usually, lame leg pushes under body.
Subjective v objective analysis.
Traditionally done subjectively:
- good visualisation with practice. Objective systems now available.
- e.g. Equinosis Q.
– recent rapid take up.
- kinematics.
– not practical in first opinion.
– only used in research.
- force plates.
– been available for long time but little used in practice.
Exacerbating lameness to assess it.
Different movements.
- (walk and trot away and back on firm level surface).
- tight turns.
- backing up (reversing).
- uphill/downhill.
Lunging on both reins.
- change surface – soft, deep, hard.
Provocation tests.
- local pressure response tests.
Lunging:
- soft surface before hard surface.
- lunging loads limb differently to travelling in a straight line.
- may exacerbate lameness on inside or outside leg.
- allows visualisation of unridden canter.
- compare the way the horse moves between the 2 reins.
- particularly helpful e.g. with foot lameness on firm circle.
- may be done before or after flexion tests.
Flexion tests.
Flex the appropriate part of the limb.
- whole limb.
- upper and lower limb in parts.
- alternate between left and right limbs.
- for same amount of time.
Allow horse to main its balance by:
- maintaining normal vertical alignment.
- do not over-lift the limb.
Important be need careful interpretation.
Non-specific to site.
Inconsistent responses.
No hard criteria.
False positives and negatives.
No “best defined” duration to hold.
Why might flexion tests be contentious in pre-purchase examination?
There are emotional and financial pressures on both parties involved.
Inviting an objective critiques of something you love and hearing that can be hard.
Sometimes a genuinely ignorant owner may be surprised to find what they thought was lame isn’t. This may make them feel inadequate or unprofessional too.
Sound horses may flex positive and what this means is not always clear. We are using it to guide against future risk too but a vendor will focus on what the horse is doing or has done. We need more EBVM here!
Other provocation tests.
Local pressure on tendons or ligaments, or swellings may elicit a painful response.
Apply pressure for a period of time and then ask for a trot.
Principle of nerve blocking.
Establish baseline lameness.
Use nerve block (perineural analgesia/anaesthesia) to numb a distal part of the limb and then assess response.
If positive, then further investigate area numbed.
If negative, progress proximally until a response is found.
Alternatively, use joint blocks to start in focal areas but be aware that this may cause perineural anaesthesia of nerves passing near the joint.
Interpreting nerve blocking with care.
Note that not everything will block out completely.
Local can diffuse up between tissue planes so may extend more proximal than you might realise.
Local can diffuse/leak from joints to block nerves as they pass the joint.
Prep for nerve and joint blocks.
Perineural blocks:
- most require minimal prep.
- may clip some e.g. feathered horses.
- those near a joint may justify sterile prep.
Joint blocks:
- MUST have sterile prep.
- clipping – obtain permission.
Restrain appropriately.
- may use twitch rather than sedation.
Appropriate agents for nerve and joint blocks.
Mepivacaine 2% (Intra-epicane).
- acts in 5 mins.
- lasts 90-120mins rarely <3hrs.
Prilocaine 2% (Citanest).
- similar.
Lidocaine.
- faster acting, shorter duration.
Bupivacaine.
- slower acting and longer lasting.
Volume depends upon site.
Often supplied as single use vials.
Be aware of cumulative doses.
Revieing the nerve/joint block.
Synovial fluid confirms correct intra-articular intrahecal placement.
Trot up from 5 mins from injections.
Some blocks may require longer than this but beware of unwanted diffusion.
Some distal blocks have areas of skin desensitisation “dermatomes”.
Think again if the answer surprises you!
