Equine Lameness and Orthopaedics Flashcards
what background information is important to obtain when getting a history of a horse with a lameness issue?
signalment
use
duration of ownership (awareness of history)
recent management (work/exercise, feeding, housing, shoeing)
previous medical problems
what problem-specific information is important to obtain from the owner of a horse presenting with lameness?
limb/limbs affected
timing and nature of onset of signs
progression of signs since onset
associated events/incidents
any swelling/heat/pain
treatments/management employed
current state of problem
what are the aims of the initial lameness workup?
decide if lame or sound identify limbs affected score the severity of lameness try to identify the source/cause implement treatment plan
what are the steps of the initial lameness workup?
physical examination
focused exam of musculoskeletal system
gait evaluation (walk/trot/lunge)
flexion tests
further examination of affected limb
what is involved in the physical examination of the horse? (5)
general clinical exam and body condition
conformation of body/limbs/feet
posture and weight bearing on the limbs
skeletal and soft tissue symmetry
localised swelling/thickenings
what is involved in a detailed evaluation of the limbs?
inspection, palpation and manipulation of the limbs/joints
palpating the soft tissue
applying pressure to see response
what do we want to establish with a gait evaluation?
is there a gait abnormality?
is this due to lameness or something else e.g.
neurological
degree of lameness, which limbs are affected
what exacerbates the lameness?
how do you perform a gait evaluation in a horse?
different surfaces - soft/hard
start with walk - if obviously lame at walk then won’t trot
trot up in a straight line
move on to lunging - soft and hard surface
what PPE should you wear in order to lead/trot up a horse?
hat
boots
gloves
overalls
what equipment is required for leading/trotting up a horse?
headcollar
lead rope
what are the considerations for trotting up?
appropriate PPE
location - safe, flat surface, weather
contained?
how lame - is it appropriate
temperament of the horse
restraint - headcollar +/- bridle
how can you assess forelimb lameness?
assess as the horse is walking/trotting towards you
will be a head nod if lame - head lifts UP as the LAME leg hits the ground
how can you assess hindlimb lameness?
assess as horse is walking away from you
“hip” of the lame limb will rise and fall through a greater range of motion than the sound side
hindquarters as a whole pushed up by sound limb and sink during stance phase of the lame limb
what are the other aspects of gait evaluation?
relative lengths of phases of stride
arc of foot flight
path of foot flight (medial/lateral)
foot placement
what is a lameness locator?
technology to aid lameness evaluation - sensors worn by horse (poll, foot and rump) - helps identify asymmetry in stride
not a replacement for standard evaluation
how is lameness graded? why grade it?
out of 10 (more common) or out of 5
useful for the individual clinician to assess improvement
what are the uses of provocative (flexion) tests?
to demonstrate occult lameness in a “sound” horse
to exacerbate mild lameness
to aid localisation of the source of lameness
how is a flexion test performed?
limb held in flexion for about 1 minute - horse trotted away as soon as limb released
allowed a few lame strides - does lameness continue longer than expected?
horse should be standing ready to trot away
attempt to only flex joints being tested
what are the limitations of flexion tests?
lack of specificity to site
inconsistency
lack of hard criteria for “positive” (allowed lame strides)
false positives and negatives
how does lunging help diagnose lameness?
lameness often exacerbated on a circle due to leaning in (suspected lame leg on inside)
hard ground more evident than soft usually
what PPE/equipment is required for performing lunging?
PPE - hat, steel toe capped boots, gloves, overalls
equipment - lunge line, lunge whip, bridle/lunging cavesson, boots for horse?
what are the other considerations when lunging a horse?
soft vs hard lunge (surfaces)
does the horse lunge well?
flat, large enough arena, appropriate surfaces
what are nerve/joint blocks?
perineural, intrasynovial or local infiltration of local anaesthetic - anaesthetises areas of the limb progressively to identify area of source of lameness
what LA is used for nerve blocks?
intra epicaine (mepivacaine)
how are nerve blocks perfomed?
start distally and work up
clean area with clorhex and spirit +/- clipping
usually unsedated (need to test movement)
left 10 mins then trot up to check for improvement
what are the common nerve block sites?
- palmar/plantar digital
- abaxial sesamoid
- low 4 point
what size needles/syringes are used for nerve blocks?
23-25G, 5/8” needles
2ml syringes
which nerve block site is this?
palmar/plantar digital
which nerve block site is this?
abaxial sesamoid
which nerve block site is this?
low 4 point - medial and lateral (4 needles)
how is a joint block performed?
intrasynovial administration - sterility is key
sterile skin prep - clorhex and spirit
evaluated at 10 mins and then later
when is diagnostic imaging performed?
once an area of source of lameness has been identified
what are radiographs useful for?
identifying bony change
why are diagnostic ultrasounds useful?
distinguishes tendon/ligament injuries from peritendonous swelling
defines which tendon/ligament is injured
evaluates type and degree of damage
monitors healing
how do you prep a limb for ultrasound?
clip if required
clean to remove dirt
apply gel to area
may require sedation to keep still
what are we looking for during ultrasound?
increase in tendon/ligament size change in internal architecture loss of longitudinal fibre alignment indistinct margination peritendinous fluid in tendon sheaths
what are hyperechoic core lesions (US)?
black hole in tendon centre
what is diagnostic arthroscopy?
direct visualisation of joint cavities, including articular cartilage, synovial membrane, intra-articular ligaments and menisci
what are the limitations of diagnostic arthroscopy?
requires GA - risk and cost
inability to examine most joints in their entirety
what is MRI useful for?
allows simultaneous demonstration of bone and soft tissue structures- good for hoof
how is nuclear scintigraphy performed?
technetium 99m linked to methylene diphosphate
injected IV, taken up into mineral bone lattice
emits gamma radiation (6 hours) which is detected by gamma camera
which lesions can be detected by nuclear scintigraphy?
stress fractures
arthropathies
enthesiopathies (connective tissue around joints)
(binds to increased metabolism/rapid turnover areas of bone)
how can uptake be increased for nuclear scintigraphy?
lunge/exercise horse beforehand
how must a horse be managed after nuclear scintigraphy?
will be radioactive - must be kept in isolation until no longer radioactive (no handling, mucking out etc)
urine will need to be collected during image acquisition
what is synovial sepsis?
bacterial contamination of a synovial structure - causes septic arthritis and chronic lameness of not treated
how can we investigate synovial sepsis?
synoviocentesis and analysis of synovial fluid
may inject sterile saline into joint and check for egress
contrast radiography?
what does checking for egress with saline mean?
checking if fluid comes out of wound
shows communication between joint and wound
what is the most important part of arthrocentesis?
maintaining sterility
how do you prep for arthrocentesis?
sterile prep with clorhex 5 min minimum
wipe with surgical spirit
horse usually sedated
what is the role of the nurse during arthrocentesis?
prepping site
non-sterile assistant during arthrocentesis
have equipment and spared ready (needles, syringes, sterile gloves, tubes/pots for collection)
monitoring for lameness/deterioration of lameness in post 48 hours (plus heat)
how might an arthrocentesis sample be analysed?
cytology - TNCC and neutrophil %
protein concentration
lactate (slow to rise in first 24hrs)
may also take blood sample for serum amyloid A
what is laminitis?
inflammation of the laminae/lamellae in the hoof
leads to dermal/epidermal separation and structural changes in the foot - rotation and sinking of P3
what is the main issue with laminitis?
causes structural changes/failure in the foot (rotation/sinking of P3)
what is the developmental phase of laminitis?
between the trigger and onset of clinical signs
what are the phases of laminitis?
developmental
acute
subacute
chronic
what is the acute phase of laminitis?
onset of clinical signs (72 hours)
may become chronic or subacute after this
what is the subacute phase of laminitis?
from 72 hours
will require 2-3 months repair
what is the chronic phase of laminitis?
structural failure
what are the clinical signs of laminitis?
stilted, pottery gait increased, bounding digital pulses leaning back on heels recumbency worse on hard ground struggle to turn due to foot placement reluctance to pick up feet
what are some of the causes of laminitis?
endocrinopathies (PPID, EMS) excessive carbohydrates excessive weightbearing endotoxaemia/SIRS corticosteroids (? anecdotal)
what are the underlying endocrinopathies which can contribute to laminitis?
equine metabolic syndrome
pituitary pars intermedia dysfunction
what is the pathophysiology of endocrinopathic laminitis?
not known but likely hyperinsulinaemia and insulin toxicity
what are the other causes of laminitis?
hospital setting
supporting limb laminitis (excessive weightbearing, fractures, cellulitis)
endotoxaemia (secondary to colic/colitis/retained foetal membranes)
what are the risk factors for laminitis?
history of laminitis obesity endocrinopathies (PPID, EMS) age insulin resistance season (pasture-related) heavy horses native ponies excessive weightbearing or carbohydrates
how can we manage laminitis in the developmental stages?
consider management for at-risk horses cold therapy - ice boots NSAIDs to reduce inflammation support for feet - frog supports, deep shavings bed treat underlying endocrinopathies
how can we manage laminitis in the acute stage?
strict and complete box rest/restricted movement
deep shavings bed
frog supports/styrofoam pads
NSAIDs - analgesia and anti-inflammatory
increase perfusion - ACP?
treat underlying cause
address diet if endocrine related - care w/ colic
farriery once more comfortable
how can we manage laminitis in the subacute phase?
gradually withdraw treatment as long as improving
keep on strict box rest
how can farriery help laminitis?
shorten toe
needs doing over time
remedial shoeing - heart bars (support frog), silicone, glue on shoes
what radiography considerations are there for laminitis patients?
lateromedial and dorsopalmar/plantar projections
measure rotation and sinking (prognostic indicators)
comfort - pick up feet and stand on blocks
metal marker on dorsal hoof wall for measurement
how can we try and prevent laminitis occurring in those with endocrinopathies?
treat underlying endocrinopathy
weight loss/promote ideal BCS
exercise if possible to increase insulin sensitivity
diet - restrict carbohydrates, soaking hay
restricted grazing - muzzles, strip grazing
what will change for the horse on box rest?
limited exercise
no turnout
behaviour - boredom, stable mates, lack of exercise
reduction in eating time
what are the main concerns with a horse put on box rest?
colic
impaction
behaviour issues
gastric ulcers
why might box rest increase the risk of gastric ulcers? how can this be avoided?
reduction in eating time due to boredom (eating faster)
omeprazole, smaller holed haynets/toys to keep occupied for longer
consider what is laminitis appropriate
what nursing considerations are there for horse on box rest?
monitor faecal output, colic signs, appetite, signs of stress
consider mirrors, company
watch out for behaviour - may be more keen to escape, difficult to handle
what considerations need to be made when a horse is coming off box rest?
gradual changes in management, gradual change in diet
behaviour when turned out - may require sedation/small field for gradual return
slow reintroduction to work
