approach to eq OA

Presenting signs

·    Low grade lameness, often bilateral FL

·    Often insidious onset, but can be sudden

·    Reduced performance

·    Signalment: middle aged-older horses (as is degenerative disease)

History

·    Slowing down

·    Reduced performance

·    Predisposing factors:

o  Workload – repetitive impacts, jumping, fast gait

o  Hard work surface

o  Hoof imbalance/poor conformation

o  Poor nutrition in early life (impacts cartilage health)

o  Previous injury

Investigations

·    Static exam

o  Effusion in coffin joint

o  Broken back hoof pastern axis, long toe low heel conformation

·    Dynamic exam

o  Mild lameness at straight trot, more obvious on lunge (greater forces going through hoof)

o  Positive result to distal limb flexion

·    Regional anaesthesia – wont resolve to palmar digital, will to abaxial or coffin joint block

·    Radiography – lateromedial view

o  Looking for: angular P3 extensor process, periosteal growth on P2, flattened condyles

o  Assess hoof pastern axis and angle of distal phalanx sole

·    Arthroscopy – assess if OC fragments present, debride necrotic cartilage

Management

·    Oral NSAIDs – phenylbutazone (cheap, easy but systemic side effects)

·    Intra-articular corticosteroids (triamcinolone, methylprednisolone)

·    +/- hyaluronic acid, stem cell autograft, PRP, bone marrow aspirate concentrate

·    Corrective farriery

o  Coffin joint OA have long toe low heel – so want to shorten toe, support heels (straight bar shoe) and add cushioning

·    Surgical treatment options – arthroscopy (debride necrotic cartilage, remove fragments), palmar digital neurectomy

·    Long term:

o  Manage workload – reduce height of jumps, decrease distances

o  Avoid hard surfaces

o  Ongoing farriery

Management

·    Oral NSAIDs – phenylbutazone (cheap, easy but systemic side effects)

·    Corrective farriery

o  Coffin joint OA have long toe low heel – so want to shorten toe, support heels (straight bar shoe) and add cushioning

·    No radiographic changes = reversible

o  Intra-articular corticosteroids + hyaluronic acid

§ Low motion joint  (PIP, distal tarsal joints) = methylprednisolone (longer acting but cause more damage to cartilage)

§ High motion joint (DIP, fetlock, tarsocrural, stifle) = triamcinolone (shorter acting results in less cartilage damage)

·    Radiographic changes = irreversible (want to get to end point so pain decreases)

o  Arthrodesis ® damage cartilage, induce inflammation and joint fusion

§ Analgesia and work

§ Chemical arthrodesis

§ Surgical arthrodesis

·    Euthanasia:

o  How much pain is horse in now? How much longer will they be in pain for?

o  Can we control this pain?

o  Are they an appropriate candidate for surgery?

Owner factors – can they afford treatment? Provide aftercare? Long term management?