Equine Flashcards
What management changes can induce lameness?
Shoeing/ related changes Training/ performance intensity Stable/ working/ turn-out surface Housing Health and diet Current medication and response, response to rest
Name a lameness condition of older horses?
Chronic progressive osteoarthritis
What does palpation of the joint assess?
Distension Temp Pain ROM
What are the 2 principles limb movement is composed of?
Travel Action
What is the definition of travel?
Flight of a single hoof in relation to other limbs. Often viewed from the side or from behind.
What is the definition of action?
Overall description of gait characteristics. Takes into account joint, flexion, stride length, suspension and other qualities. Variation between different types and breeds
What are the phases of the stride?
Landing (+ gliding), loading, stance, brakeover (heel lift, toe pivot), swing
What are the features of the walk and how good is it at assessing lameness?
Even rhythmn 4 beat gait. Not v suitable for subtle lameness
What are the features of the pace and how good is it at assessing lameness?
Two beat lateral gait- ipsilateral fore- and hindlimb. Viable for STB racehorses and some others. Considered impure for most normal horses. Also not v easy to assess if subtle
What are the features of the canter and how good is it at assessing lameness?
3 beat gait with lead preference. Difficult to assess subtle lameness but useful for back/ rider/ saddle associated problems
What are the features of the trot and how good is it at assessing lameness?
2 beat diagonal gait. Steadiest and most rhythmic- preferred for lameness exam
What are the objectives of gait observation?
Is the animal lame- which legs? How lame?- appreciate difference w/ diagnostic analgesia? Localise the source of lameness in limb to allow for targeted diagnostic imaging and tx
How is a lameness recognised?
Fetlock drop- usually more on sound limb. Exception w/ tendon or SL damage Changes in limb flight- cranial and caudal phase of stride
What is the classic pattern of a forelimb lameness?
Head nod- when puts sound limb down
What is the classic pattern of a hindlimb lameness?
Pelvic hike
Elevation tuber calcis- higher on lame side
Drifting- moves away from lame limb, lame limb tracks under body (most often) or is posted out
Sound- harder landing on sound limb
What is the pelvic hike?
Hiking of pelvis when lame limb weight bearing Dropping of pelvis when sound limb is weight bearing Greater excursion of lame hindlimb- distance between top height and bottom height
How has the equine distal limb best adapted to locomotion?
Walking on one finger- stability over flexibility Reduced muscle mass- reduced swing time–> higher speed, tendons- efficient energy storage Straight- decreased joint forces/ moments
What are the features of the flexor tendon muscles?
Highly pennate. Muscle fibres ~1cm–> limited capacity for length change
What are the features of tendons?
Stores and releases energy. 7& lost as heat.
How have the bones in the distal limb been reduced?
Radius and ulna fused. Weight-bearing on the third MC/MT and digit. Lengthening of the limb, mass reduction. Increased energy storage (tendons). Lighter limb, shorter swing time, less mechanical energy.
What are the mechanical functions of the hoof?
Shock absorption, support and grip, propulsion.
What are the protective mechanisms of the hoof?
Shape of solar surface allows heel movement. Suspension of distal phalanx- forces transferred via distal border of hoof wall. Digital cushion- shock absorption and frog movement. Hoof sliding. Rotation and translation of DIP joint.
How does increased speed increase risk of injury?
Increased speed, decreased stance time. Force generated in less time, incr energetic cost. Incr peak limb force. Incr risk of injury
How are the phases of stance critical to injury?
1st impact- large accelerations, low forces, incr bruising 2nd impact- low acceleration, high forces, natural breaking Large vertical force- excessive dorsiflexion of fetlock Breakover/ propulsion- tensile strength
Which tendons are high strain and which are low strain?
SDFT+SL- high strain DDFT+DAL- low strain % length change w/ force
What adaptations to horses joints decrease the metabolic cost?
Reduction of phalanges and fusion of bones–> movement in saggital plane only. Interlocking configuration (ridges/ grooves) and collateral ligaments–> restriction of movement w/out muscular control, decrease in metabolic cost
How does a heel wedge affect loading of tendons?
Moves PZM towards heels thus reducing DIP momentt arm- unloads DDFT and NB
How does hoof trimming help improve strength?
Horn arranged in tubules- ideal to withstand high compressive forces. This diminishes w/ length. *collapsed/ underrun heels- tubules start bending when grown distal to the distal phalanx, impairment of natural hoof deformation and BF, application of carbon fibre patches benificial
What is laminitis?
Failure of attachment of the epidermal cells of the epidermal (insensitive) laminae to the underlying BM of the dermal (sensitive) laminae
What are some of the risk factors for laminitis?
Diseases characterised by sepsis and systemic inflamm Endocrine disorders- PPID, EMS Mechanical overload Access to pasture Metabolic disorders Retained placental membranes
What are some predisposing factors for pasture-associated laminitis?
Pony Season (spring/ summer) Gender (F) Incr age Obesity Insulin resistance
What are the 3 stages in the pathogenesis of laminitis?
Developmental (contact w/ trigger, lasts up to 72h) Acute laminitis Resolution or chronic laminitis
What is the role of the ECM in the laminae?
Responsible for maintenance of structural support, movement, growth, remodelling and healing, along w/ modulation of cytokines, inflamm, healing and cell migration
Why can laminar separation occur following and insult?
Failure of epithelial adhesion molecules (hemidesmosomes) which attach the epidermal cells to the BM
What types of insults can cause laminar separation?
Inflammatory and/or hypoxic cellular injury
What are two endocrinological disorders that may play a role in the predisposition to laminitis in certain horses?
Excess glucocorticoids- PPID Insulin resistance- EMS
What will exacerbate insulin resistance in horses?
Increased CHO consumption
What vascular events occur in the early stages of laminitis?
Digital venoconstriction and consequent laminar oedema
What are the aims when approaching a suspected case of laminitis?
Make a definitive dx Determine underlying cause Determine if likely to recover to expected level of soundness
How is a diagnosis of laminitis reached?
Clinical signs, +/- radiography and endocrine tests
Name the clinical signs of laminitis
-Lameness affecting 2/more limbs. -Characteristic chance -Bounding digital pulses -Incr hoof wall temp -Pain on hoof tester pressure at the region of the point of the frog -Palpable depression at the coronary band
What are some radiographic signs of laminitis?
-Pedal bone rotation -Founder distance -Angle between line of P3 and wall of hoof (should be parallel) -Decreased sole thickness
What endocrine tests may be appropriate for dx of laminitis?
PPID: CS, basal ACTH, Dex suppression (not autumn), TRH stim test EMS: hx, CS, demonstration of IR
What are three that can be done to medically treat laminitis?
Analgesia Vasodilation/ vasoconstriction Foot support- essential, incr bedding, frog/ sole support
What can be used for analgesia in laminitic horses?
NSAIDs (PBZ, flunixin, carprofen etc. IV/oral) Opiates (morphine, pethadine, fentanyl etc)
What is the main tx for PPID?
Pergolide
What is the main tx for EMS?
Weight loss, exercise, may/ may not use pharmacological agents
What is NSC and when does it increase/ decrease?
Energy for growth of plants. Incr when plant photosynthesising. Decr when plant growing. Aim is to minimise NSC content
What can be done to high quality hay to decrease NSC content?
Soak hay in water for at least 20 mins, not reliable however.
If a laminitic horse needs extra energy, what can be added to the diet to provide it?
Oil, unmollassed beet pulp
What are some mineral supplements that can be added to the diet to help with insulin levels?
Cinnamon Magnesium Chromiun
What are the indications for imaging of the equine foot?
Lameness is localised to the foot. Penetrating wounds. Prepurchase. Farriery management
What are the routine views for imaging of the equine foot?
Lateromedial Dorso-60’-proximal palmarodistal oblique (collimated for navicular bone/ distal phalanx) Dorso-45’-proximal palmarodistal oblique (collimated for navicular bone) Palmaro-45’-proximal palmarodistal oblique
How are XRay views named?
Point of entrance of XRay beam to point of exit
What variation occurs in normal radiographic anatomy of the collateral cartilages?
Variation in ossification. Separate centres of ossification may resemble fractures.
How is the dorso-60°-proximal palmarodistal oblique view of the equine foot taken?
How is the palmaro-45°-proximal palmarodistal
oblique taken?
Flexor view