Equine Orthopedics Flashcards
what background information should be gained when performing a lameness work up on a horse?
signalment use duration of ownership recent management previous medical problems
why is duration of ownership of horses valuable information?
shows owner awareness of history
what should be asked about horses recent management before a lameness workup?
work/exercise
feeding
shoeing ( barefoot / frequency of trims)
housing
why is useful to know about the use of a horse when diagnosing lameness?
possible differential diagnosis
owner expectations for recovery
what specific history is needed for a lameness work up?
limb or limbs affected
timing and nature of onset of signs
associated events or incidents
details of any areas of swelling, heat or pain
progression of signs since onset
treatments or management employed to date
current state of problem
what are the aims of the initial lameness workup?
decide if horse is lame or sound identify limb(s) affected score severity of lameness try to identify source / cause implement treatment plan
what are the steps involved in an initial lameness workup?
general physical exam focused exam of MSK system gait evaluation (walk, trot and lunge) flexion tests further exam of affected limb
what may be involved in a further lameness workup, following initial?
nerve or joint blocks
diagnostic imaging
what is involved in the general physical exam in a lameness workup?
general clinical exam (TPR) general body condition conformation of body, limbs and feet posture and weight bearing on the limbs skeletal and soft tissue symmetry localised swellings/thickening (from a distance)
what may posture and weight bearing on limbs tell you about lameness?
whether the horse is trying to reduce pain
how should skeletal and soft tissue symmetry be assessed?
stood square on a flat surface
what is involved in a detailed physical exam of the limbs?
feeling limbs, joints and soft tissue
inspection
palpation
manipulation
what are hoof testers used for?
applied to hooves in various places to put pressure on and assess response
what is done after the physical exam during a lameness workup?
gait evaluation
what do we need to establish from gait evaluation in a lameness workup?
is there gait abnormality is the abnormality due to lameness or something else e.g. neurological what degree of lameness is there which limbs are affected what exacerbates lameness
where should gait evaluation be performed?
different surfaces - soft and hard if facilities allow
what should the gait evaluation start with?
walk
why should all gait evaluation start with walk?
if obviously lame at walk should not trot due to further injury risk
what is involved in gait evaluation?
walk
trot in a straight line
lunging on soft and hard surfaces
what PPE is needed for trotting up?
hat gloves steel toe capped boots overalls gloves
where should horses be trotted up?
safe area
enclosed / contained
flat surface
care with surface if raining
when may trotting / walking up not be appropriate?
if horses is severely lame
what must be considered about the horse before trotting up?
temperament
restraint
how may horses be restrained for trotting up?
headcollar
bridle if needed
when should forelimb lameness be assessed?
a the horse is walking / trotting towards you
how is forelimb lameness identified?
head nod
head lifts UP when lame leg hits the ground
when is hindlimb lameness assessed?
as the horse is walking / trotting away from you
is forelimb or hindlimb lameness easier to identify?
forelimb
how is hindlimb lameness identified?
hip of the lame limb will rise and fall through a greater range of motion than the sound side
how will the hindquarters as a whole behave if a horse is lame?
pushed up by sound limb and sink during stance phase of lame limb
what else can be assessed during gait evaluation?
relative lengths of phases of stride
arc of foot flight
path of foot flight (medial or lateral)
foot placement
what is a lameness locator?
technology used to aid lameness evaluation
sensors are worn by the horse and computer program helps to identify asymmetry in the stride
where may lameness locator sensors be placed?
poll, hoof and rump usually
what is a lameness locator useful for?
helping clinician to identify and quantify subtle lameness
not a replacement for visual evaluation
what are the 2 main systems used to grade lameness?
out of 5
out of 10
what system of grading lameness is the most common?
out of 10
when reassessing and grading lameness who should assess?
clinician who assigned initial grade as there are individual differences
what are the uses of flexion (provocative) tests?
demonstrate occult lameness in a ‘sound’ horse
exacerbate mild lameness
aid localisation of lameness source
what is assessed in flexion tests?
response of the limb to flexion
what happens during a flexion test?
limb held in flexion for ~1 minute
horse trotted away as soon as the limb is released
how should the horse be standing for a flexion test?
ready to trot away (straight line, facing away)
what is assessed during a flexion test?
does lameness continue longer than would be expected after flexion (horse allowed a few lame strides)
what joints should be flexed during flexion tests?
attempt to only flex those you are testing (easier said than done!)
what are the limitations of flexion tests?
lack of specificity to site
inconsistency
lack of clear criteria for positive - what is the cut of of allowed lame strides
false positives and negatives
why is lunging of benefit in a lameness work up?
lameness often exacerbated on a circle
when lunging when is lameness particularly obvious?
when lame leg is on the inside due to increased weight bearing
what surfaces can lunging be performed on?
hard and soft ground
why is hard ground lunging useful?
usually exacerbates lameness more (although not always)
what PPE is needed for lunging?
hat
steel toe capped boots
gloves
overalls
what equipment is needed for lunging?
lunge line
lunge whip
bridle / cavesson
boots
where is lunging performed?
soft lunge - school or pen
hard lunge - hospitals will usually have designated flat area that is secure and has appropriate surface
what questions should be asked before lunging?
does the horse lunge well
when are further lameness workups needed?
established that horse is lame, how lame and what leg
what is involved in a further lameness work up?
physical exam of specific limb(s)
diagnostic analgesia
diagnostic imaging
what is involved in nerve ant joint blocks?
perineural, intrasynovial or local infiltration of LA into areas of the limb to progressively identify area of source of lameness
what LA is used for nerve and joint blocks?
Intra-epicaine (mepivicaine)
where should nerve blocks be started?
distally and work up
how should the area be prepped for nerve blocks?
clean area with chlorhex and spirit
can be clipped
how are nerve blocks usually performed?
unsedated as movement is assessed
safety is crucial
how should nerve blocks be performed?
LA injected
leave for 10 mins and then trot up to check for improvement
what does improvement of lameness after a nerve block indicate?
problem is located between nerve blocked areas
what are the 3 nerve blocks used in lameness workup?
palmar/plantar digital
abaxial sesamoid
low 4 point
what equipment is needed for nerve blocks?
23-25G, 5/8” needles
2ml syringes
identify the nerve block
medial and lateral palmar/planter digital
identify the nerve block
abaxial sesamoid (medial and lateral) location of digital pulse
identify the nerve block
low 4 point (medial and lateral - 4 needles)
where are joint blocks performed?
blocking into a joint (intrasynovial)
what is key when administering joint blocks?
sterility
how should skin be prepped for joint blocks?
sterile skin prep - chlorhexadine and spirit
when are the results of joint blocks evaluated?
10 mins and then later to see if there has been LA infiltration
when is lameness diagnostic imaging performed?
once an area of source of lameness is identified
why do we need to narrow down source of lameness before diagnostic imaging is performed?
to limit imaging and so radiation exposure
what can be interpreted using diagnostic imaging?
significance of any finding
what does the choice of diagnostic imaging modality depend on?
suspected source of lameness
what PPE is needed for radiographs?
lead gowns
thyroid protectors
how are horses usually restrained for imaging?
sedation to keep them still
what are radiographs useful for?
identifying bony change
what is ultrasound used for in horses?
distinguishing tendon/ligament injuries from peritendinous swelling
defines the tendon/ligament that is injured
evaluates type and degree of damage
monitors healing
how should horses be prepped for ultrasound?
clip area if required
clean to remove dirt
apply US gel
how are horses restrained for US?
may need sedation to stay still
what are you looking for during diagnostic ultrasound in a lameness workup?
Increase in tendon/ligament size
Change in internal architecture
Indistinct Margination
Peritendinous fluid in tendon sheaths
what changes in internal architecture of tendons may be seen on ultrasound?
hypoechoic core lesions
heterogenous pattern -
loss of longitudinal fibre alignment
what are hypoechoic core lesions?
black hole in centre of tendon
what is diagnostic arthroscopy?
direct visualisation of joint cavities with a scope
what can be viewed during arthroscopy?
Articular cartilage
Synovial membrane
Intra-articular Ligaments
Menisci
what are the limitations of diagnostic arthroscopy?
Requirement for general anaesthesia
Inability to examine most joints in their entirety
what is the benefit of MRI and CT?
Cross sectional imaging of complex anatomical structures
what is the benefit of MRI for lameness investigation?
simultaneous demonstration of bone and soft tissue structures
see within hoof
what can be evaluated by MRI?
tendons/ligaments and other soft tissues
how does nuclear scintigraphy work?
radioactive isotope is linked to marker which binds to metabolically active bone injected IV taken up by bone emits radiation gamma camera detects radiation
what radioisotope is used in nuclear scintigraphy?
technetium 99m
what is the marker used in nuclear scintigraphy?
methylene diphosphonate
how long does the radioisotope emit radiation for?
half life is 6 hours
what lesions can be detected by nuclear scintigraphy?
Stress fractures
Arthropathies
Enthesiopathies - connective tissue
what should happen to the horse prior to injection of radioisotope if safe?
lunged or exercised
why should as horse be lunged or exercised prior to nuclear scintigraphy if safe?
increases uptake
what must be placed before nuclear scintigraphy is performed?
IV catheter
what is the disadvantage of nuclear scintigraphy?
horse will remain radioactive for a period of time after injection
how should the horse be managed after nuclear scintigraphy scan?
Urine will need to be collected during the image acquisition
Must be kept in isolation until no longer radioactive - no handling, no mucking out etc.
what is synovial sepsis?
bacterial cntamination of synovial structure
where dies synovial sepsis often occur?
wounds in adults that penetrate joints
what does synovial sepsis cause if not treated?
septic arthritis and chronic lameness
how should suspected synovial sepsis be investigated?
Synoviocentesis and analysis of synovial fluid
May inject sterile saline into the joint and check for egress
Contrast radiography
what is vital when performing arthrocentesis?
sterility
how should the patient be prepped for arthrocentesis?
Sterile prep of the athrocentesis/synoviocentesis site
Chlorhexidine 5 min minimum scrub
Wipe with surgical spirit
what needle is required for arthrocentiesis?
depends on joint
what restraint is usually used for arthrocentesis?
sedation
what is the role of the nurse in arthrocentesis?
Prep the site (vets may choose to prep this themselves)
Non-sterile assistant during arthrocentesis
Have equipment and spares ready (e.g. needles, syringes, sterile gloves, tubes/pots for collection)
Monitoring for lameness/deterioration in lameness in the post 48 hours
what is shown by injection of sterile saline into the joint and there being egress from wound?
communication between joint and wound so likely infection
why must the patient be monitored closely for 48 hours following arthrocentesis?
procedure can cause synovial sepsis
what is analysed from arthrocentesis?
cytology
protein conc
lactate
serum amyloid A (SAA) blood sample
what is cytology of arthrocentesis sample checking for?
TNCC and neutrophil %
what tubes are needed for arthrocentesis?
EDTA or cytospin for cytology
plain tube - culture and TP
define laminitis
inflammation of the interdigitating laminae/lamellae in the hoof
what does laminitis cause?
dermal/epidermal separation and reduction in structural integrity of the hoof
is laminitis painful?
yes - very
what can laminitis lead to?
structural changes/failure in the foot
what structural changes / failure in the foot can be caused by laminitis?
rotation of P3
sinking of P3
what are the 4 main phases of laminitis?
developmental
acute
subacute
chronic
when does the developmental phase of laminitis occur?
between trigger and clinical signs
what happens during the acute phase of laminitis?
onset of clinical signs
how long does the acute phase of laminitis usually last?
72 hours
what can happen after the acute phase of laminitis?
may become chronic or subacute
when does subacute laminitis occur?
from 72 hours after onset of acute signs
how long does subacute laminitis take to repair?
2-3 months
what happens in chronic laminitis?
structural failure of the structures of the hoof
what are the clinical signs of laminitis?
stilted, pottery gait increased, bounding digital pulses leaning back on heels recumbancy worse on hard ground struggle to turn reluctance to pick up feet
what are the main causes of laminitis?
endocrinopathies excessive carbohydrates excessive weightbearing endotoxaemia / SIRS corticosteriods
is the absolute pathogenesis of laminitis known?
not precisely understood
potentially multiple mechamisms
how may excessive carbohydrates cause laminitis?
grain overload
pasture (linked to PPID)
what underlying endocrinopathies can cause laminitis?
equine metabolic syndrome (EMS)
pituitary pars intermedia dysfunction (PPID)
what is the likely pathophysiology of the link between endocrinopathies and laminitis?
disregulation of insulin leading to hyperinsulinaemia and insulin toxicity
what are the vast majority of the cases of laminitis caused by?
endocrinopathies (although depends on population)
what are the majority of pasture related laminitis cases caused by?
endocrinopathies - sugars in pasture cause insulin spike
what are the causes of laminitis seen most commonly in the hospital setting?
supportive limb laminitis
endotoxaemia
how is supporting limb laminitis caused?
excessive weightbearing
especially if on one limb only
what conditions often lead to supporting limb laminitis?
fractures
cellulitis
how can endotoxaemia be caused and so lead to laminitis?
secondary colic
colitis
retained fetal membranes
what are the risk factors for laminitis?
history of laminitis obesity endocrinopathies (PPID, EMS) age (PPID) insulin resistance leptin/adiponectin (EMS) season heavy horses native horses excessive weightbearing excessive carbohydrates risk of endotoxaemia
when can laminitis be prevented?
developmental phase before clinical signs
what patients should have preventative laminitis management?
those at risk - endotoxic, RFM, supporting limb
how is developmental laminitis managed?
cold therapy with ice boots to reduce perfusion
NSAIDS reduce inflammation
support for feet
how can feet be supported to manage developmental laminitis?
frog supports
deep shavings bed
what is the role of frog supports in managing developmental laminitis?
lift heel to reduce pressure from DDF on P3
how should horses with developmental laminitis and endocrinopathies be treated?
treat underlying endocrinopathy
discussion of prevention and long term management (e.g. diet and weight loss)
how should acute laminitis patients be managed?
strict and complete box rest / restricted movement
deep shavings bedd
frog supports or Styrofoam pads
NSAIDS - analgesia and reduce inflammation
ACP to increase perfusion (vasodilation)
treat underlying cause
address diet
how should the diet of an acute laminitis patient be addressed if they have endocrinopathies?
reduce carbohydrates (e.g. steam or soak) but not dramatically
why is it important to reduce carbohydrates in a horses diet gently if needed?
reduce risk of colic and hyperlipaemia
what should be done to treat acute laminitis once the patient is more comfortable?
farriery
how should subacute laminitis be treated?
gradually withdraw treatment as long as improving
keep on strict box rest
radiology and farriery to alter foot balance
how can radiography and farriery be used to treat subacute laminitis?
shorten toe over time
use radiographs to calculate shortening needed
remedial shoeing
what remedial shoeing may be used for laminitis patients?
heart bar shoes
silicone
glue on shoes
what are the main radiographic views needed for laminitis assessment?
lateromedial
dorsopalmar/planter
what is the aim of radiographs for the laminitis patient?
measure rotation and sinking of P3
look for prognostic indicators
what prognostic indicators may be seen on a hoof radiograph of a laminitis patient?
separation of laminae e.g. gas shadowing
why may radiography be difficult in a very painful laminitic?
need to have feet picked up and stand on blocks
what must be placed on the dorsal hoof wall to ensure measurements can be taken from radiographs?
metal marker from coronary band down the front of the hoof wall
what is the angle of rotation?
angle between dorsal hoof wall and dorsal boarder of P3 - should be no intersecting angle as line should be paralledl
how can laminitis be managed / prevented?
control risk factors
treat underlying endocrinopathy (if present)
weight loss - promote ideal endocrinopathy
diet
restrict graing
what can be beneficial to reduce insulin sensitivity?
exercise
how should the diet of a horse prone to laminitis be manged?
restrict carbohydrates
soak hay and give balancer to replace nutrients
how should grazing for the laminitis prone horse be restricted?
not by time
strip grazing
grazing muzzle
which of the laminitis risk factors is it possible to directly manage?
obesity endocrinopathy insulin resistance diet excessive weightbearing endotoxaemia
what is box rest?
stabling 24/7 in a confined space with no exercise or turnout
what changes for the horse when it is put on box rest?
limited exercise change in routine change in diet (required) no turnout may be unused to stabling boredom reduction in time eatng
how may the horses behaviour be affected by box rest?
separation from friends
boredom
lack of exercise leading to excessive energy
what are the main GI considerations for a horse on box rest?
management changes can lead to colic
reduced exercise can reduce gut motility - impaction colic
sudden diet changes can lead to colic
diet will have to be adjusted for new energy requirements
ulcers due to reduced eating time
how can the risk of ulcers due to reduced eating time on box rest be reduced?
omeprazole
small holed haynets
food toys - consider illness being treated!
what are the main behaviour considerations for a horse on box rest?
may develop stereotypies if bored / frustrated
unused to stabling so may be stressed
separation from stable mates - mirror?
increased energy leading to poor behaviour in stable and trying to escape - may barge / spook when allowed out
how should the patient on box rest be nursed?
monitor faecal output monitor for colic monitor appetite and signs of stress offer mirrors or a form of company watch out for behaviour changes - more keen to escape and more difficult to handle
how should patients come off box rest?
gradual changes in management back to normal
gradual change back to normal diet
gradual return to turn out
slow reintroduction to work
what should you be wary of when a horse is first turned out after box rest?
gradual return to turn out
sedation or small field for first time out
watch behaviour
