approach to eq laminitis

Presenting signs

·    Overweight, high BCS, cresty neck

·    Reluctance to move

·    Lameness

·    Abnormal stance – leaning back to put more weight on HLs

·    Evidence of endocrine disease (PPID: hirsutism, pot belly, EMIS: excess BCS, cresty neck)

History

·    Previous laminitis events?

·    Recent diet/management changes? Current diet?

·    On any medications recently? – antibiotics (am associated dysbiosis)

·    History of D+? – endotoxins released by clostridium/salmonella cause increased MMP production

·    Any known endocrinopathies, e.g. EMS, PPID? Any concurrent injuries?

·    When did clinical signs begin? Any progression?

·    When were they last trimmed/shod?

Investigations

·    Clinical exam

o  Feel feet – digital pulses? Heat? Visible growth rings = previous episodes?

o  Hoof testers – any pain?

o  Assess BCS – cresty neck

·    Dynamic exam – watch them walk and turn

·    Radiography of feet – both R and L

o  Lateral view

§ Angle of pedal bone – should be parallel with hoof - >10° = severe

§ Sinking of pedal bone ® increased pressure on sole

§ Remodelling of P3 tip

§ Hoof overgrowth

o  Dorsopalmar view

§ Collapse of pedal bone on one side

Management

·    Initial management

o  Analgesia – NSAIDs (phenylbutazone), can add in paracetamol or buprenorphine if horse really painful

o  ACP – vasodilator, improve blood supply to distal limbs

o  Support feet – frog support shoes, soft deep bedding

o  Ice feet

o  Weight loss

§ Reduce calorie intake – 1.5% bw of soaked hay (gets rid of sugar)

§ Once pain under control, can start to increase exercise

·    Long term management: regular re-examination and adjust meds accordingly, regularly trim feed, gradually increase exercise

o  Once pain under control can test if suspect underlying endocrine disease:

§ EMS: baseline insulin/oral sugar test

§ PPID: baseline ACTH

Pathophysiology

·    Dermal/P3 laminae and epidermal/hoof laminae interdigitate – MMP breaks down bonds to allow growth, then bonds reform

·    Increased MMP activity ® breakdown of bonds without reforming ® separation of hoof and pedal bone

Causes

·    Endocrine causes:

o  Obesity/EMS – increased body fat ® insulin resistance + hyperglycaemia ® more insulin produced by body ®

o  PPID – excess ATCH ® hyperinsulinaemia ® stimulates extra MMP production

·    Non-endocrine causes:

o  Toxic – sepsis, endotoxaemia ® increased MMP production

o  Support limb lameness – less weight on lame limb, increased pressure through contralateral limb ® decreased blood flow to laminae ® hypoxia ® inflammation + MMP production