Foot Penetrations & Hoof Wall Conditions (BEVA 2022) PDF

Foot penetrations and conditions of the hoof wall MOD 2021/22 Dr Peter Milner Senior Lecturer Equine Orthopaedics BEVA 2009 Learning outcomes • To identify and treat conditions involving the hoof wall and associated structures • To understand the aetiology of foot penetrations in the horse • To e...

Foot penetrations and conditions of the hoof wall MOD 2021/22 Dr Peter Milner Senior Lecturer Equine Orthopaedics BEVA 2009 Learning outcomes • To identify and treat conditions involving the hoof wall and associated structures • To understand the aetiology of foot penetrations in the horse • To evaluate and treat a horse with a foot penetration In this lecture we will cover • • • • Hoof cracks Injuries to the coronary band and hoof wall Puncture wounds to the foot Other infections/conditions of the hoof (quittor, keratoma, canker, white line disease) Heel bulb Collateral sulcus Central sulcus Angle of bar Seat of corn Bar Frog apex Sole Hoof wall White line Hoof cracks • Usually run in a proximo-distal direction (with horn tubules) – Inciting cause (poor foot balance/care; poor horn quality; environment; trauma) – Occasionally transverse cracks (associated with coronary band injury) • Hoof cracks may be “complete” or “incomplete” • Instability leads to shear forces, further separation, (infection) and pain Hoof cracks - treatment • Characterise depth, direction, – Determine sensitive/insensitive parts (do not nerve block) – Incomplete often just need trimming/shoeing • Farriery • Debride/dremmel all necrotic tissue; • Filler to stabilise (plate; wire) • Trim foot/unload crack/bar shoe/quarter clips • Identify underlying cause (and treat) • Antibiotics (local/systemic) – Flush via catheter/tubing Injuries to the coronary band and hoof wall • Aetiology – Wire lacerations/foot trapped (e.g. gate/fence)/overreach injuries • Clinical signs – Avulsion/disruption to the hoof wall +/- coronary band – Lameness • Moderate/severe – Haemorrhage++ • Digital cushion highly vascularised – Involvement of other important structures • DIP/PIP/NB/DFTS • Tendons/ligaments (DDFT/SDFT/extensor tendons/collateral ligaments) Injuries to the coronary band and hoof wall treatment • Primary or secondary intention healing? – Close on presentation or delay closure? – Often heavily contaminated – Preserve coronary band if you can! • Suture coronary band • Stabilise hoof wall (wiring/cast/shoe) – Check tissue viability • Antibiotics • NSAIDs – Pain relief/anti-inflammatory Injuries to the coronary band and hoof wall treatment • Bandaging – Initially to protect/debride tissue • Cast – Very useful! – Foot/distal limb casts often the best way to stabilise • Flushing synovial structures – Treat sepsis early and aggressively • Shoeing Puncture wounds of the foot • Common cause of lameness – Most are managed conservatively with a good prognosis • But… • All foot penetrations have the potential to involve deeper structures resulting in life threatening complications • Appreciation of anatomy is essential! What kind of objects are involved? • • • • • • Nails Screws Bolts Wire Stones/flints Glass Penetrations associated with shoeing • Nail bind • Nail close to sensitive structures • Mild lameness • Pain around nail • Shoeing prick • Nail into sensitive structures • Immediately painful/blood • May develop into subsolar abscess if left Subsolar abscessation • Common +++ • Penetration of bacteria results in abscess formation and pressure on sensitive hoof lamina • Usually acute lameness • SEVERE! • Increased digital pulse • Increased hoof temperature • Sensitive to hoof testers • Key: DRAINAGE • Remove shoe/nail (if present) • Pare foot – follow tracts and remove all necrotic/underrun horn Subsolar abscessation • Poultice/tub • 1-2 x daily • MgSO4 • Bandage • Protect foot • (NSAIDs/antibiotics) • Tetanus prophylaxis • Re-shoe once dry/hardened • Severe cases – hospital plate Foot penetrations involving synovial structures Diagnosis: • Moderate to severe lameness • Presence of nail/foreign body in foot, particularly the middle third • Puncture wound – can be difficult to find sometimes • Distal limb swelling/DIP effusion/DFTS effusion • Increased digital pulse to foot • Sensitive to hooftesters over tract (but can be hard to perform in the painful horse) Foot penetrations involving synovial structures • Radiography • +/- probe • Contrast study • Synoviocentesis • NB/DIP/DFTS • MRI Foot penetrations involving synovial structures - treatment • Debridement of infected tissue • Removal of necrotic horn/tendon • Flushing of affected synovial structures • Navicular bursoscopy/DIP arthroscopy/DFTS tenoscopy • Resection of damaged tissue • Systemic ab’s/IVRA/intrasynovial medication/PMMAbeads in tract Foot penetrations involving synovial structures - outcome • Bandaging then hospital plate + raised heel • NSAIDs • Success rate: • Infection: fair (56% survival to discharge – Findley et al 2013) • Return to athletic function: guarded (due to involvement of DDFT/impar ligament) (36% return to pre-injury function – Findley et al 2013) Causes of chronic hoof absecssation • May be masked by antibiotics or persist from poor drainage/ insufficient removal of necrotic tissue • Check for underlying causes • Immunocompromise e.g Cushing’s • Keratoma • Sequel to laminitis (poor quality laminae) • Bone sequestrum/collateral cartilage infection • Infective (pedal) osteitis Quittor • Infection of the collateral cartilages • Trauma/wound • Swelling/chronic discharge from coronary band • Tx: surgical debridement of infected tissues • Be careful of the DIPJ! Keratoma • Benign tumour of the hoof/solar horn – Chronic inflammation/infection? • Intermittent lameness/discharge • Characteristic circular area of abnormal keratinisation with discharging tract • Radiography may show smooth, radiolucent defect in P3 • Surgical resection under GA BEVA 2009 Canker • Chronic condition associated with hypertrophy of the germinal layer of the epithelium of the frog – May affect frog, bars, heels and sole • Often linked with Fusobacterium/Bacteriodes spp. • Infection leads to dyskeratosis of the keratin producing cells • Results in abnormal hyperkeratotic horn with keratolysis and fronds of unconnected intertubular horn Canker • Early/mild cases – Improve environment – Debride abnormal areas – Apply metronidazole bandages +/- systemic abs – Astringents : • Picric acid (5%) and benzoyl peroxide (10%) – Dilute formalin (0.1-1%) – Care: epithelial layer • Advanced/severe cases – Aggressive surgical debridement – Bandaging/shoeing Recurrence common! © BEVA 2009 White line disease • Progressive, crumbling, poor quality hoof wall with separation at the white line – Non-pigmented portion of the stratum medium and the laminar horn • Environmental, nutritional and mechanical factors – Warm, wet weather – Biotin/methionine/zinc/selenium deficiency – Bacterial infection common • Clinical signs – +/- lameness – Separation of hoof wall esp at toes/quarters – Grey/black crumbly horn White line disease - treatment • Remove abnormal horn – Hoof knives/dremmel – Hoof wall removal • Support remaining horn – Bar shoe+clips – Hoof acrylic • Prevent progression – Environmental factors – Topical povidone/iodine – Feed supplementation At the end of this session you should be able to: • Identify and treat conditions involving the hoof wall and associated structures • Understand the aetiology of foot penetrations in the horse • Evaluate and treat a horse with a foot penetration