Equine MSK disease 4 Flashcards
How may sepsis or synovitis of the tarsal joint commonly occur in horses?
Kick to plantar/medial aspect of the hock
List the synovial structures in the hock that may be affected by trauma in the horse, and where relevant, state what they contain
- Calcaneal bursa: superficial part of SDFT
- Tarsal sheath: surrounds DDFT
- Tarsocrural joint
- Proximal intertarsal joint
- Distal intertarsal joint
- Tarsometatarsal joint
List the causes of stifle lameness in the horse
- DJD
- OCD
- Bone cysts
- Fractures
- Joint effusion
- Septic arthritis
- Meniscal injuries
- Cruciate injuries
- Collateral ligament injuries
- Patellar ligament injuries
Outline the clinical signs of stifle lameness in the horse
- Proximal limb lameness exacerbated by soft ground
- Abduction when avoiding flexion of joint
- Reduced ROM
- Pain on flexion
- Joint effusion in one or more of the 3 compartments
- Pain on palpation (should be able to palpate all 3 patellar ligaments, and medial and lateral menisci)
- Crepitus if fractures
What are the 3 joint compartments of the stifle in the horse? Which are usually implicated in joint effusion?
- Femoropatella (most common)
- Medial femorotibial (meniscal disease)
- Lateral femorotibial
What would indicate a rupture of the peroneus tertius in the horse?
Ability to flex stifle and extend hock - should usually flex together
Describe the joint communications in the stifle horses, and explain the importance of this
- Femoropatellar joint usually communicates with medial femorotibial joint
- Communicates with the lateral FT joint in 25% of horses
- The FT joints do not communicate with each other
- Need to block each one individual if performing intra-articular anaesthesia
Explain how pain is localised in the equine stifle
- Intra-articular anaesthesia, block each joint individually
- No perineural anaesthesia!
What is the most common soft tissue injury of the equine stifle?
Medial meniscal injury
Outline the diagnosis of medial meniscus injury the horse
- Medial femorotibial (+/- femoropatella) effusion
- Radiography: presence of changes = poor prognosis
- Ultrasonography: evaluation of soft tissues e.g. medial and lateral meniscus, collateral ligaments, patella ligaments, components of cruciate ligament
- Arthroscopy (soft tissues and cartilage)
Describe the ultrasonographic features that may be present in a medial meniscal injury in the horse
- May have signs of DJD
- Bony remodelling
- Meniscus bulging out of joint
- Irregular shape of meniscus
- Differences in echogenicity
- May see tear
Explain the usefulness of radiography for establishing a prognosis for stifle injuries in the horse
- Many are soft tissue injuries, but can be used to indicate degree and treatment required
- Signs of DJD indicate for return to athletic function
- Identification of bony lesions e.g. OCD, subchondral bone cysts, DJD, fractures
Describe the normal ultrasonographic appearance of the equine meniscus
- Triangular and flush with the bone
- Collateral ligaments run over the top
- Should be homogenous
- May have blood vessels present that cause shadowing
Discuss the use of arthroscopy in the diagnosis of meniscal injury in the horse
- Can combine diagnosis and treatment
- But costly and requires GA
- Cannot facilitate complete evaluation of the menisci or cruciate ligaments
Outline the treatment options for meniscal injuries in the horse
- Rest and NSAIDs
- Arthroscopic debridement
Discuss the prognosis for meniscal injuries in the horse
- Return to function 50-60%
- Poorer prognosis if radiographic changes present (arthroscopy unlikely to be useful)
- Degree of lameness reflects prognosis
- Older horses = poorer prognosis
Briefly outline cruciate injuries in the horse (which cruciate, associated pathology, diagnosis, treatment, prognosis)
- Cranial cruciate
- AP: menisci, collateral ligaments, articular cartilage
- Dx: radigraphy, arthroscopy
- Tx: arthroscopic
- Px: depends on severity and presence of radiographic changes
Which collateral ligament is most commonly injured in the horse?
Medial collateral
In which horses are patellar ligament injuries most likely to occur, and what often occurs concurrently?
- Jumping horses
- Commonly see patellar fractures/pathology
Discuss the aetiology of subchondral bone cysts in the horse
- Unclear
- May be developmental or traumatic
Where are bone cysts commonly seen in the equine hindlimb and how are these diagnosed?
- Medial femoral condyle
- Latero-medial radiograph, palmar-dorsal radiograph (caudo-15-proximal to cranio-distal oblique projection may be better)
Outline the treatment of subchondral bone cysts in the stifle of the horse
- Debridement of cyst
- Arhtroscopic injection of steroid into cyst cavity
Discuss the prognosis for subchondral bone cysts in the equine stifle
- Approx. 60% come sound
- Older horses have worse prognosis
- Radiographic changes of DJD indicate worse prognosis
What structures in the equine forelimb are commonly affected by kick wounds?
Bony prominences e.g. splint bones, olecranon
Which structures in the equine forelimb are commonly affected by trauma/concussion
- Pastern
- Metacarpus
Which structures in the equine forelimb are commonly affected by stress fractures?
- Metacarpus
- Radius
- Humerus
- Scapula
Discuss the management of open fractures of the splint bones in horses
- Rest, bandaging, anti-inflammatories
- Antibiotics
- Surgical removal possible, can be done standing
- If proximal, risk of involvement of joint, need more aggressive approach
What is a serious complication of kick wounds to the area of splint bones that may not be noted on radiography?
- Non-displaced fractures of the cannon bone
- Displace catastrophically during recovery from anaesthesia
Describe the appearance of ulnar/olecranon fractures in the horse
- Dropped elbow
- Similar to radial paralysis
Discuss the management and prognosis of ulnar/olecranon fractures in the horse
- Consider referral for surgical repair
- Usually good prognosis with repair
Describe the clinical signs of stress fractures in the horse
- lameness (single/multiple limbs possible)
- Variable presentation and duration
- Absence of clinical signs in affected limb possible
- Localised inflammation
- regional pain response to palpation/manipulation
- Specific tests e.g. tibial torsion test
Where are stress fractures commonly found in the equine hindlimb?
- Sacrum
- Pelvis
- Tibia
Identify the methods that can be used in the diagnosis of stress fractures in the horse
- Clinical signs and history (intense exercise, lameness associated with work)
- Diagnostic anaesthesia
- Scintigraphy
- Radiography
- Ultrasonography
- MRI, CT
Outline the management of equine stress fractures
- Modify exercise patterns
- Change intensity, level and/or type of exercise
- Ensure balanced nutrition (calcium 23g/day, phosphorous 23g/day)
- Extracorporeal shock wave therapy and pulsed electromagnetic fields anecdotal evidence
In which horses, and in which joints are articular fractures most common?
- Racehorses
- Fetlock
- Sesamoid bones
- Carpus
Outline the treatment of articular fractures in horses
- Remove small fragments (arthroscopically, or arthrotomy)
- Stabilise larger fragments using screws
- Treat joint inflammation
Which horses are predisposed to fracture of the second phalanx and in which limb does this most commonly occur?
Quarter horses, in the HLs
What types of fracture most commonly occur in the second phalanx?
- Palmar/plantar eminence fractures of proximal P2
- Or comminuted fractures
Outline the treatment of fracture of the second phalanx in horses, and discuss the prognosis
- Internal fixation using plates and screws and/or transfixation pin cast
- Lameness usually present after, depends on degree of OA that develops in dip and PIP
- Prognosis depends on comfort of horse after fracture stabilisation and contralateral laminitis development
In which horses is fracture of the first phalanx more common
Any horse used for performance
Outline the clinical signs of fracture of P1 in the horse
- Usually traumatic, hyperextension of fetlock
- Acute lameness, effusion of fetlock
- Sensitive to firm flexion of fetlock
- Lameness at speed
Outline your diagnostic approach for a suspected P1 fracture in the horse
- Radiography
- May need intra-articular diagnostic analgesia to implicate as cause of lameness
Outline the radiographic appearance of P1 fracture in the horse
- Osteochondral fragment fracture along dorsal margin of proximal joint surface (chip fracture)
- Sagittal fracture (complete/incomplete)
- Or Comminute fracture
In which horses does chip fracture of P1 more commonly occur?
Racing breeds, horses exercising at speed
What is meant by type I and type II P1 fractures in the horse?
- Type I: axial fractures, generally articular
- Type II: abaxial, minimal articular cartilage present
Outline the treatment of chip P1 fractures in the horse
Remove arthroscopically, excellent prognosis if no other joint abnormalities
Outline the treatment of routine, non-displaced sagittal P1 fractures in the horse
internal fixation with lag screws placed via stab incisions
Outline the treatment for complex fractures of P1 in the horse
Open reduction with placement of lag screws
Outline the treatment of comminuted P1 fractures in the horse
- Immobilise with plaster/fibreglass cast for up to 12 weeks
- With or without use of transfixation pins through third metacarpal/tarsal bone
Describe the common fractures of the metacarpus in the horse
- Most common is lateral condyle
- Lateral condylar: mid to midaxial, traverse toward lateral cortex, rarely spiral
- Medial condylar fractures: extend towards axial aspect of cannon bone
- Vertical fracture in sagittal plane of distal metacarpal bone in young racehorses
What is the most common major long bone fracture in horses and how does it commonly occur?
- Fracture of diaphyseal cannon bone (metacarpal bone)
- Usually trauma while pastured with other horses
Give and explain the preferred treatment for a diaphyseal metacarpal bone fracture in the horse
- Open reduction and internal fixation
- Little soft tissue coverage, cast/coaptation would not provide enough support
What radiographic views are required for the diagnosis of metacarpal fractures in the horse?
- Full series
- Fetlock
- Flexed dorsopalmar views
Outline the treatment for condylar fractures of the metacarpus
- Lateral: can be treated conservatively with splinting, treatment of choice is compression with lag screws (minimises OA)
- Medial: lag screw fixation distally, plate placed up remaining metacarpus
Where sesamoid fractures of Standardbreds and TBs most commonly occur and how do these occur?
- Most are apical
- Caused by overextension and often associated with suspensory ligament damage
How do lateral proximal sesamoid fractures in the HL of Standardbreds commonly occur?
Torque forces induced by shoeing with trailer-type shoe
List the types of sesamoid fractures that may occur in the horse
- Apical
- Mid-body
- Basilar
- Abaxial
- Axial
- Comminuted
(NB most common in the lateral proximal sesamoid)
Outline the clinical signs of sesamoid fractures in the horse
- Heat
- Pain
- Acute lameness, exacerbated by flexion of fetlock
- Haemarthrosis
- Synovial effusion of metacarpal/tarsophalangeal joint
Outline the treatment of different types of sesamoid fractures
- Apical sesamoid fractures: remove fragments arthroscopically
- Mid body fractures: reduction using lag screws
- Surgical arthrodesis of fetlock if have complete disruption of suspensory appratus, including both sesamoids bones in order to salvage for breeding
In which horses do osteochondral fractures of the carpal bones occur and why?
- Race horses
- Trauma associated with fast exercise
What are the main clinical signs of carpal bone fracture in the horse?
- Synovitis
- Capsulitis
Where are carpal chip fractures in the middle carpal joint usually located?
- Dorsal aspect
- Middle carpal: distal radial carpal bone, proximal third carpal bone, distal intermediate carpal bone
Where are carpal chip fractures in the radiocarpal joint usually located?
- Proximal intermediate carpal bone
- Distal lateral radius,
- Proximal radial carpal bone
- Distal medial radius
Outline slab fractures of the third carpal bone in the horse
- One articular surface to another
- Can be in frontal or sagittal planes
- Most common: frontal slab fracture of radial facet of third carpal bone
- Less common: fractures of intermediate facet and both facets of the third carpal bone
Outline accessory carpal bone fractures in the horse (incl. treatment and prognosis)
- Less common
- Acute lameness, severe, may see synovial effusion in carpal sheath and radiocarpal joint
- Radiographs confirm diagnosis
- Treat conservatively
- If articular and fragmented, remove fragments
- Fibrous unions may enable horse to return to normal activity
Outline the treatment and prognosis of carpal chip fractures in the horse
- Arthroscopic surgery to remove fragments
- Prognosis depends on degree of articular cartilage damage
Outline the treatment of carpal slab fractures in the horse
- Lag screw for fractures >10mm
- Removal of fragments if thin/not amenable to lag screw fixation
List the sites of fracture of the shoulder in the horse
- Supraglenoid tuberosity of scapula
- Mid to distal scapula
- Proximal humeral metaphysis
Outline the clinical signs of shoulder fracture in the horse
- Dropped shoulder in supraglenoid fractures
- Mid to distal scapular fractures often trauma related
- Sudden onset lameness with stress fractures, often with exercise
Outline the diagnostic tools that can be used for shoulder fracture in the horse
- Radiography (rarely helpful due to region, good for periosteal and endosteal new bone at site of proximal humeral fractures)
- Ultrasonography
- Scintigraphy
Outline the treatment and prognosis for supraglenoid fracture in the horse
- Large: repair surgically
- Remove smaller fragments
- Resect biceps tendon of origin
- Prognosis guarded, depends on size, displacement, articular involvement, degree of biceps disruption, intended use -
Outline the treatment of mid to distal scapular fractures in the horse
Simple, non/minimally displaced fractures usually heal with rest alone
Outline the treatment of deltoid tuberosity fractures in the horse
- Usually recover with rest alone
- Surgical debridement of infected bone in rare cases
Outline the treatment of proximal humeral fractures in the horse
- Confinement counterproductive
- Light exercise (walk only) once lameness subsided
What are the most common sites for synovial sepsis in the equine forelimb and how is this diagnosed?
- Distal limb: flexor tendon sheath, pastern joint, fetlock joint
- Diagnosed with synoviocentesis
How do luxations of the fetlock (FL or HL) occur in the horse?
- Rupture of medial or lateral collateral ligaments or avulsion fracture
- Usually caused by trapping distal limb in hole, trailer/transport injury, high speed exercise
Outline the clinical signs of fetlock luxation in the horse
- Sudden onset non-weight bearing lameness
- Angular limb deformity of distal limb
- History of injury/trauma
- Excessive movement in fetlock joint
- Variable soft tissue trauma, often little swelling initially
Outline your approach to the diagnosis of fetlock luxation in the horse
- Confirmed on radiography
- Also identified any complicating bone injury
- Ultrasonography to assess collateral ligaments
Outline your treatment approach to simple luxation of the fetlock in a horse and the prognosis
Reduction and cast immobilisation to achieve pasture soundness
What are the possible causes of proximal interphalangeal joint luxation in the horse?
- Traumatic tearing of collateral ligament
- Fracture of P1 or 2
- Loss of suspensory or palmar support structures
What may cause dorsal subluxation of the DIP in the horse?
- Loss of fetlock support
- Contraction of straight sesamoidean ligament
- Flexural deformity of DIP
- Suspensory ligament desmotomy with DDF tenotomy
What may cause palmar subluxation of the DIP in the horse?
Tearing of palmar support structures e.g. jump from height, landing on FLs
Outline the clinical signs of proximal interphalangeal joint luxation in the horse
- Acute, non-weight bearing lameness
- Acute swelling over site of luxation, local heat
- Pain on manipulation
- Firm swelling in chronic cases
- Malalignment of metacarpus/metatarsus , proximal phalanx and middle phalanx
- Dorsal sublux: dorsal pastern swelling, dropped fetlock
- Palmar sublux: concave dorsal pastern, sinking pastern at wall, heels contact ground
Outline the radiographic positioning and appearance of proximal interphalangeal joint luxation in the horse
- Standard and stressed views
- See uneven joint space
- May see middle phalanx fracture, minor avulsion fractures
- Displacement of proximal phalanx
Outline the treatment of proximal interphalangeal joint luxation in the horse
- Depends on cause and time since injury
- Treat concurrent fractures specifically
- Surgical arthrodesis usually best option
- NSAIDs
Outline the prognosis of proximal interphalangeal joint luxation in the horse
- Depends on cause and time of treatment
- Generally good for salvage purposes
- Arthrodesis guarded prognosis for performance processes
Outline the signs of scapulohumeral joint luxation in the horse
- Non-weight bearing
- Shoulder atrophy if chronic
- Humeral head palpated lateral, or cranial to the scapula
Outline the diagnosis of scapulohumeral joint luxation
- Best demonstrated on standing caudolateral to craniomedial oblique views
- Look for fractures of humeral head to scapula, esp. rim of glenoid
Discuss the treatment of scapulohumeral joint luxation
- Closed reduction followed by scapulohumeral joint arthroscopy to evaluate articular surfaces and remove cartilage debris
- Must be within 24 hours, and before open approach performed
Discuss the prognosis of scapulohumeral joint luxation
- Eventually OA and severe lameness, resulting in euthanasia
- Arthrodesis an option, but rare
Describe the pathophysiology and appearance of suprascapular nerve damage in the horse
- Damaged by blunt trauma to point of shoulder
- Innervates supraspinatus and infraspinatus muscles
- Causes muscle atrophy and lateral luxation of shoulder joint
Describe the pathophysiology and appearance of radial nerve neuropathy in the horse
- Post-anaesthetic neuropathy, or trauma
- Animal unable to protract limb
- Dropped elbow
What condition may present similarly to radial nerve neuropathy in the horse?
Ulna fractures can present similarly due to disruption of triceps brachii insertion
List the conditions of the equine hindlimb that are critical
- Joint infection
- Fracture
- Tendon ruptures
- Luxations
List the nerve and joint blocks using in diagnosis of hindlimb lameness
- Palmar digital
- Abaxial sesamoid
- Femoropatella and both femorotibial joints
- Tibial and peroneal nerve blocks
- PIT, DIT, TMT
What is innervated by the tibial nerve in the horse?
- Extensors of hock
- Flexors of digit
- Skin on caudomedial aspect of limb and plantar and dorsal aspect of foot
What is innervated by the peroneal nerve in the horse?
- Flexors of hock and extensors of digit
- Skin on craniolateral aspect of limb
What should we aim for when performing radiography in the horse?
- Minimal exposure/risk to staff
- Diagnostic films of region of interest
- Minimal repetition of views (minimum number of exposures possible)
Outline the safety precautions that should be taken when performing radiography of a horse’s limb
- Have maximum distance between other animals/people and the x-rays
- Minimum number of staff (>18, not pregnant) (3 should be enough)
- Use markers to centre beam and reduce no. of exposures
- Ensure good restraint of horse using stocks, ties, sedation, head rests
- Careful measuring of film focal distance
What skeletal conditions could cause cystic lesions within bones of the horse’s limb?
- Osteochondrosis
- Subchondral bone cyst
