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Flashcards in Equine MSK diseases 3 Deck (100)
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Discuss the use of scintigraphy in the diagnosis of back pain in horses

- Extremely sensitive for bone lesions incl. fractures, new bone, infective processes and bone tumours
- Often unrewarding for back soft tissue injuries
- Good for pelvic disorders


Discuss the use of ultrasonography in the diagnosis of back pain in horses

- Imaging of supraspinous ligament
- Imaging of spinous processes
- Identification of overriding dorsal spinous processes (kissing spine)
- Poor for muscle injuries
- Good for pelvis, esp. ilial fracures


Describe the ultrasonographic appearance of overriding dorsal spinous processes in horses

- Tips of spines appear very close together
Marked narrowing at the affected interspinous spaces
- Pseudoarthrosis may be visible: anechoic area surrounded by well-defined capsule


List the tests, other than imaging, that can be used for the diagnosis of back pain in horses

- Lab tests (muscle enzyme activities - AST, CK, lactate)
- Local anaesthetic blocks
- Infiltration of steroids
- Electrical stimulation of epaxial musculature (rare)


Why is trial treatment with NSAIDs useful in the diagnosis of back pain in horses?

Confirmation of presence of pain - differentiate between behaviour and pain


Outline the management of a horse with back pain

- Conservative: box rest, physiotherapy
- Surgical for some causes e.g. kissing spine, some fractures
- Keep horse as light as possible, diet altered accordingly
- May need to consider effect of rider (poor rider, or heavy)


Discuss the prognosis for chronic soft tissue injuries causing back pain in horses

- Guarded prognnosis
- Difficult to confirm
- Need to start treatment including rest, controlled, exercise and physio for several months before declaring unfit for work


List possible causes of lameness originating the equine foot

- Solar/white line infection
- Thrush
- Solar bruising/solar pain
- Hoof wall lesions
- Wounds
- Laminitis
- Foot imbalance/caudal foot pain
- Navicular disease
- DIP joint pain/DJD
- Foot penetrations
- Fractures


List the key features of the initial observation in a lameness examination of the horse

- Weight bearing or not? (Stance)
- Foot balance (conformation)
- Uneven wear of hoof/shoe
- Compare left and right foot
- Shoeing (type, when shod)


Which tendons are affected by a palmar imbalance in horses?

More pressure on flexor tendons


Outline the key features of the physical examination of a lame horse relating to the feet

- Palpate for heat, pain, swelling, digital pulses
- Check show and nail position
- Check sole surface


List the conditions that commonly cause heat, pain, swelling of the foot and palpable digital pulses in the horse

- Laminitis
- Infection
- Sole bruising
- Fractures
- Joint effusions


Outline the typical findings on physical examination in a case of laminitis

- Hot feet, bounding digital pulses
- Can be single limb (overload laminitis), both FLs, or all 4 limbs
- Other systemic signs e.g. tachyC and sweating may be present


Outline the typical findings on physical examination in a case of infection in the equine foot

- Hot foot, bounding digital pulses
- Usually unilateral (sole or white line infections)


Outline the typical findings on physical examination in a case of solar bruising in a horse

- Hot foot, bounding digital pulse
- Usually unilateral, can be bilateral
- Usually FL (takes more weigh)
- Hoof testers/paring away hoof reveals bruising/haemorrhage


Outline the typical findings on physical examination in a cause of foot fractures in a horse

- Hot foot, bounding pulse
- If P2 may have swelling and palpable crepitus


What are the key considerations for when evaluating the movement of a horse in a lameness examination

- Degree of lameness
- Limb/limbs affected
- Effect of surface
- Effect of load (left reign vs right reign)
- Effect of flexion of distal limb
- Need to rule out fractures prior to trotting horse


List the contraindications for diagnostic anaesthesia in a lameness examination in a horse

- Suspected fractures
- Severe soft tissue injuries e.g. DDFT rupture
- Risk of infection e.g. current infection at injection site such as mud fever, or if cannot be performed sterile


List the options for diagnostic anaesthesia for the diagnosis of lameness originating in the equine foot

- Perineural anaesthesia
- Intra-articular anaesthesia
- Distal interphalangeal joint
- Navicular bursal block
- Digital flexor tendon sheath block


What is the main difficulty with diagnostic anaesthesia in the equine foot?

Communication and overlap between different areas is inconsistent between horses e.g. DIP is up against navicular bursa, sometimes communicates allowing perfusion of local anaesthetic between structures, sometimes does not


For which conditions of the equine foot is radiography the first line of diagnostics

- Suspected fracture
- Laminitis
- Suspected bone lesions/foot penetrations


What are the standard views of the equine foot?

- Lateromedial
- Upright pedal
- Upright navicular
- Flexor navicular


What is the first line diagnostic test for synovial sepsis?

Arthrocentesis - no nerve blocks, no radiographs


When is use of ultrasonography indicated in equine foot lameness?

Only soft tissue lesions, limited value due to hoof


When is use of gamma scintigraphy indicated in equine foot lameness?

- Used in non-displaced pedal bone fractures (non radiographic signs)
- May not see much


Discuss the use of MRI in the diagnosis of equine foot lameness

- Very useful, allows assessment of all structures in the foot
- Good for soft tissues e.g. DDFT insertion on P3, collateral ligs of DIP joint
- Expensive


Outline the aetiology of laminitis

- Ischaemic necrosis → vasoconstriction
- Damage to interlaminar bodies, loss of epidermal/dermal junction, separation of laminae
- → separation of P3 from hoof wall


Outline the clinical signs of acute laminitis

- Uni/bi/quadrilateral lameness possible
- Hot foot, bounding pulse, characteristic stance
- TachyC, hypertension, sweating
- Severe: depression at coronary band, protrusion/haemorrhage at sole at toe region


Outline the diagnosis of laminitis

- Radiography
- Lateromedial view with markers on sole and coronary band, and dorsal hoof wall
- Divergence of hoof wall and dorsal P3 measured
- Remodelling in toe area in chronic cases


Discuss the prognostic factors for laminitis

- <5˚ separation = good prognosis
- >15˚ separation = poor prognosis
- Rapid deviation = poor
- Slow = better


Outline the treatment for laminitis

- Treat underlying cause
- Vasodilators and NSAIDs
- Frog supports, soft deep bedding
- Dorsal wall resection(stop rotation, release seroma fluid)


Outline the importance and treatment of foot balance abnormalities

- Predisposes to other conditions e.g. navicular pain, palmar heel pain, DDFT lesions, DIP joint disease
- Corrective farriery


What is meant by navicular disease and how does it occur?

- Pain in navicular region; bone, bursa or soft tissues
- Biomechanical use


Which horses are predisposed to navicular disease?

Middle aged horses, esp. TB and Warmbloods


Outline the clinical signs of navicular disease in the horse

- Usually FL
- Uni/bi lateral
- Chronic, progressive lameness
- Worse on hard ground
- Periods of box rest may trigger episodes
- +/- Toe point when resting
- Chronic cases have smaller, upright feet


Outline the diagnosis of navicular disease

- Bilateral lameness (short striding or obvious when lunged)
- Positive flexion tests
- Positive to palmar digital nerve block, +/- positive to DIP joint block, positive to navicular nerve block
- Lameness may become more apparent in contralateral limb following nerve block
- Radiography: LM, DPr-60PaDi upright, PaPr-PaDi oblique
- +/- gamma scintigraphy, MRI


Outline the radiographic appearance of navicular disease

- Radiographic signs may not be present, or may be present in abscence of lameness
- New bone formation (lateral and medial wings)
- Loss of corticomedullary junction
- Irregular/cyst like radiolucencies
- Remodelling of distal border (upright pedal) or flexor surface (flexor view), incl. fractures
- Calcification of soft tissues


Outline the conservative treatment options for navicular disease

- Correction of foot balance and farriery
- Avoid rest, need to encourage movement
- Intra-bursal steroid injections
- Systemic NSAIDs
- Isoxuprine
- Bisphosphonates


Outline the surgical treatment options for navicular disease

- Endoscopy of navicular bursa and DDFT
- Suspensory lig. desmotomy
- Neurectomy


Discuss the use of neurectomy in the treatment of navicular disease

- Cut nerves to prevent pain but can still work
- Ethical issue - condition will worsen but will not be felt
- Illegal in some competitions
- Risk of damage to other foot structures


What may cause DIP joint pain the horse?

- Synovitis
- Degenerative joint disease
- Trauma/fractures
- Infectious arthritis


Outline the clinical signs of distal interphalangeal joint disease resulting from synovitis or DJD

- Insidious onset
- Uni/bilateral lameness
- Usually FLs
- Lameness worsened by increased workload, hard ground
- Joint effusion palpable
- Often related to foot balance


Outline the diagnosis of distal interphalangeal joint disease in horses

- Positive to flexion tests
- Worse when lunged on hard ground, affected limb inside
- Full/partial response to palmar digital nerve blocks, positive to abaxial sesamoid nerve block, positive to DIP joint block
- Radiography


Outline the radiographic appearance of DIP joint disease in horses

- Radiographic signs (osteophytes) seen on joint margins (extensor process of P3, distal P2 on LM view)
- Radiographic changes can be subtle


Discuss the significance of finding radiographic signs in DIP joint disease in a horse

Signs of DJD associated with a poor prognosis for return to soundness


Outline the treatment of DIP joint disease in horses

- Identify and treat underlying cause
- Correct foot balance (farriery)
- Treat inflammatory/degenerative cycle
- systemic NSAIDs, intra-articular steroids
- Modify exercise (work on soft ground, gentle, keep regular, may need weight loss)


List uncommon causes of lameness originating from the equine foot

- Penetrations
- Cysts in pedal and navicular bone
- Pedal osteitis
- Keratoma
- Sidebone
- Quittor
- Canker


What is a keratoma in the equine foot a key differential for?

Recurrent infection


What is "sidebone" in horses?

Ossification of collateral cartilages, usually no clinical significance


What is quittor in a horse?

- Uncommon
- Infection of collateral cartilages of pedal bone leading to coronary band and hoof wall pathology


What is canker in a horse?

- Uncommon
- Soft caseous discharge from frog and heel bulb region
- Difficult to manage and treat


List the main causes of lameness associated with the equine forelimb

- Foot pain
- Cellulitis/lymphangitis
- Pastern degenerative joint disease
- Fetlock DJD
- Splints
- Tendon and ligament injuries
- Carpal DJD
- Synovial sepsis, fractures, luxations
- Neoplasia


List the causes of limb swelling in a horse

- Cellulitis and lymphangitis
- Pupura haemorrhagica (strangles)
- Equine viral arteritis
- Hypoproteinaemia/fluid overload/cardiac failure


What is innervated by the radial nerve in a horse?

- Extensors of elbow, carpus and digits
- Skin sensation on craniolateral aspect of limb


What is innervated by the median nerve in a horse?

- Flexors of carpus and digit
- Skin sensation on palmar aspect and dorsal digit


What is innervated by the ulna nerve in the horse?

- Flexors of carpus and digit
- Caudal aspect of forearm, lateral and dorsal digit


Which forelimb nerves are the key ones to be blocked for a lameness examination in a horse?

Median and ulna


Outline your initial approach to the lameness examination for the equine forelimb

- Observation (conformation etc.)
- Palpation (asymmetry, heat, swelling, pain)
- Range of movement


Outline the use of diagnostic tests in the diagnosis of forelimb lameness in the horse

- Radiography (first line of diagnostics, before nerve block)
- Ultrasonography for suspected soft tissue lesions
- Arthrocentesis if suspect joint sepsis
- Perineural anaesthesia unless # or tendon/ligament
- MRI, CT for some difficult lesions, complicated fractures/bone lesions


When is the use of ultrasonography indicated as the first test for the diagnosis of equine forelimb lamaness?

When soft tissue lesion is suspected e.g. tendonitis, bursal swellings
- Swollen, hot, painful indicates tendonitis
- Do not block/trot suspected tendonitis until know severity by ultrasonography


What is cellulitis and how does it occur in the horse?

- Inflammation of subcut tissues
- +/- infection
- Site of bacterial entry may be wound, skin infection e.g. mud fever, or deeper infection
- May be localised around the wound, or spread throughout limb


Outline the clinical signs of cellulitis in the horse

- Heat, pain, swelling
- Usually diffuse swelling, can have localised abscesses as well
- +/- pyrexia
- Varying degree of lameness
- Elevated white cell count


Outline your approach to a case of suspected cellulitis in the horse

- Identify underlying cause
- Rule out complicating factors e.g fractures, snynovial sepsis, osteomyelitis
- Treat underlying cause (incl. establishing drainage for pockets of infection)
- Antibiotics and anti-inflammatories


Discuss the antibiotic selection for a case of cellulitis in the horse

- Systemic required (spread through tissues)
- Penicillin, cephalosporins, potentiated sulphonamides effective: good for skin contaminants, good penetration of skin/soft tissues
- But cephalosporins and TMPS ineffective against anaerobes


What is lymphangitis and how does it develop in the horse?

- Inflammation of lymphatic system of the limb
- Impaired lymph drainage leads to build up of fluid in limb
- May be trigger by infection, once affected horse may be predisposed to repeats


Outline the clinical signs of lymphangitis in the horse

- HL more common than FL
- Bi or uni lateral
- Diffuse soft tissue swelling
- Prominent lymphatics
- Can progress to serum oozing through skin
- May have abrasions/site of infection
- Similar appearance to cellulitis


Outline the treatment of lymphangitis in the horse

- Identify and treat underlying cause
- Antibiotics and steroids (Dex IM followed by oral pred, NSAIDs if owner worried)
- Physical therapy: cold hosing, bandaging, walking exercise
- Need to treat aggressively, prone to recurrence, may get chronic limb swelling


Discuss the development of pastern DJD in the horse

- Low motion joint, disease may be advanced before clinical signs
- May have inciting causes e.g. sepsis, fracture, bone cysts/OCD
- Repeat concussion/turning forces


What may be felt in a horse with pastern DJD?

New articular bone growth palpable as a bony swelling


Describe the diagnosis of pastern DJD in the horse

- Blocked by abaxial sesamoid nerve block
- Intra-articular anaesthesia
- Radiography to rule out underlying causes and monitor progression


Outline the treatment of mild pastern DJD in the horse

- No radiographic changes
- Intra-articular anti-inflammatories (e.g. hyaluronic acid, PsGAGs)
- If pain free, continue riding


Outline the treatment of pastern DJD in the horse where radiographic signs are present

- Disease will continue to progress, hyaluronic acid no use
- NSAIDs to manage pain
- Surgical arthrodesis if cannot be managed with NSAIDs, weight loss and exercise


What are the 4 main causes of fetlock joint disease in the horse?

- Developmental (OCD and bone cysts)
- Trauma/repetitive injury
- Articular fragments
- Major fractures that extend to joint


What are the main causes of fetlock lameness in growing horses?

- Bone cysts
- Angular limb deformities
- Flexural deformities


List less common causes of fetlock lameness in the horse

- Soft tissue injuries
- Sepsis
- Luxations


Outline your diagnostic approach to a fetlock lameness in the horse

- History and palpation
- Nerve blocks (unless suspect #): abaxial sesamoid, low 4 point, intra-articular (confirm joint involvement)
- Radiography (also contralateral limb): 4 oblique views + specialised obliques


Outline the treatment of fetlock lameness in the horse (consider articular fragments, OCD, bone cysts, subchondral bone disease, synovitis, osteoarthritis)

- Removal of articular fragments if small
- Stabilise large fragments with plate and screws
- Remove/debride OCD lesions
- Debride bone cysts
- Rest horses with subchondral bone disease
- Intra-articular anti-inflammatories for synovitis
- Anti-inflammatories and analgesia for chronic OA


What is meant by "splints" as a cause of lameness in the horse?

Enlargement of the region of the 2nd and 4th metacarpal and metatarsal bones


How does "splints" develop in the horse?

- Ligament between splint bones and 3rd metacarpal/tarsal can be torn
- Thought to be caused by trauma and subperiosteal haemorrhage


Outline the clinical signs of splints in the horse

- Usually younger horses starting/increasing work
- FL more than HL
- 2nd metacarpal more than 4th
- Some but not all cause lameness


What type of conformation may predispose to the development of splints in the horse?

Bench knee


What is the most likely cause of lameness in a young horse, where physical examination demonstrates heat, pain, swelling around proximal splint bone



Outline the diagnosis of splints in the horse

- Usually based on clinical signs
- can confirm on radiography or use nerve blocks to confirm site of pain


Outline the treatment of splints in the horse

- Swelling will persist following treatment, but may not be clinically significant if not causing pain
- Anti-inflammatories
- Reduce/stop work until lameness settles
- Cold hosing
- May require surgical removal if new bone impinges on suspensory ligament (rare)


What is the most common cause of lameness originating in the carpus of horses?



Outline the clinical signs of osteoarthritis in the carpus of a horse

- Lameness
- Joint effusion
- Bony swelling
- Reduced ROM
- Pain on flexion


Outline your diagnostic approach for suspected osteoarthritis in the carpus of a horse

- Joint effusion and pain on palpation indicates need for radiography
- Nerve blocks if fracture ruled out (intra-articular if localising signs present: middle carpal and carpometacarpal as one, middle and antebrachiocarpal as separate blocks)


Outline your treatment approach for osteoarthritis in the carpus of a horse

- Anti-inflammatories
- Analgesia
- Removal of articular fragments if present


Discuss the prognosis of osteoarthritis in the midcarpal and antebrachiocarpal joints in the horse

- Are high motion joints
- Radiographic signs in these joints indicate poor prognosis for return to athletic function due to presence of irreversible damage


List the main causes of hindlimb lameness in the horse

- Cellulitis/lymphangitis
- DJD of small tarsal joints/Spavin
- Meniscal disease of the stifle
- Subchondral bone cysts of the stifle
- OCD of the stifle and hock
- proximal suspensory desmitis
- Synovial sepsis
- Fractures
- Luxations
- Tendon ruptures
- Luxations (less common)


What is spavin?

Degenerative joint disease of the small tarsal joints in the horse


Discuss the distribution of joints affected in spavin in the horse

- Tarsometatarsal and distal intertarsal usually
- Sometimes proximal intertarsal
- Worst affected if tarsocrural joint is affected


Describe the lameness seen with spavin in the horse

- Can be uni or bilateral
- If bi, may appear stiff, or gait problem esp. in canter
- Lameness can be mild or severe
- Often pain on flexion e.g. when being shod


Outline your diagnostic approach for a case of suspected spavin

- Conformation, palpation, lameness evaluation, flexion tests
- Intra-articular anaesthesia: TMT and DIT separately, PIT (will also block tarsocrural as these communicate) - required for definitive diagnosis
- +/- Perineural anaesthesia (tibial and peroneal nerve block)
- Radiography of hock showing signs of joint disease


Outline the use of radiography in the diagnosis of spavin in the horse

- LM and DP views of hock, D45LPM and D45MPL obliques
- Radiographic signs: narrowing of joint space, periarticular osteophyte formation, subchondral bone sclerosis, subchondral bone lucency
- Severity of radiographic signs does not always relate to severity of the lameness


Outline the treatment of spavin in a case where there are no radiographic changes

Intra-articular anti-inflammatories only


Outline the treatment of spavin in a case where there are radiographic changes

- Intra-articular anti-inflammatories
- Conservative: intra-articular steroids 1-3 months, systemic NSAIDs, continue to work horse
- Surgical: arthrodesis of joint (can be chemical or surgical), will be pain free after fusion


Briefly outline how chemical arthrodesis works in the management of spavin

- MIA (monoiodoacetate) or ethanol
- Inject into joint: damages cartilage, kills nerves
- Exercise as much as possible to encourage fusion of bones


List the common causes of lameness originating in the tarsus of horses

- Synovitis of tarsocrural joint
- OA of tarsocrural joint
- Intra-articular fragments
- Luxations and collateral ligament injuries
- Sepsis of the joint


Discuss the location of synovial sepsis in the tarsus and the importance of this

- Tarsocrural joint common site
- Small tarsal joints can be affected, are difficult to flush
- Need to consider other synovial structures e.g. tarsal sheath and calcaneal bursa
- Tarsocrural joint communicates with the PIT