Equine Foot Diseases PDF

DISEASES OF THE EQUINE FOOT 2 Henre Honnas, DVM Large Animal Surgery, Resident III Outline Lecture 1 Laminitis Foot pain Thrush Hoof cracks Hoof injuries White line dz Keratomas Canker Lecture 2 Sub-solar abscess Pedal osteitis Puncture wounds Navicular syndrome Fractures Anatomy of the foot Ø Bones...

DISEASES OF THE EQUINE FOOT 2 Henre Honnas, DVM Large Animal Surgery, Resident III Outline Lecture 1 Laminitis Foot pain Thrush Hoof cracks Hoof injuries White line dz Keratomas Canker Lecture 2 Sub-solar abscess Pedal osteitis Puncture wounds Navicular syndrome Fractures Anatomy of the foot Ø Bones * Distal phalanx (P3) * Middle phalanx (P2) * Proximal phalanx (P1) * Distal sesamoid bone (navicular bone) Ø Synovial structures Distal interphalangeal (coffin) joint Proximal interphalangeal (pastern) joint Metacarpophalangeal (fetlock) joint Digital flexor tendon sheath Navicular bursa Ø Tendon and ligaments # Deep digital flexor tendon (DDFT) Ø Sesamoidean ligaments # Impar ligament * * * #* # Ashdown, Atlas of Veterinary Anatomy Subsolar Abscess Localized pocket of infection under the hoof sole/wall Most common cause of acute lameness in horses Treatment often very rewarding Pathway of least resistance Subsolar Abscess Etiology History – Penetrating wound – Seedy toe – Severe lameness 4/5 – Subsolar bruise – “Hot” nail – “Fracture lame” – Distal limb swelling can be present – Does not always respond to nerve blocks – Idiopathic – Secondary Laminitis, keratoma, or pedal osteitis Subsolar Abscess Etiology History – Penetrating wound – Seedy toe – Severe lameness 4/5 – Subsolar bruise – “Hot” nail – “Fracture lame” – Distal limb swelling can be present – Does not always respond to nerve blocks – Idiopathic – Secondary Laminitis, keratoma, or pedal osteitis Subsolar Abscess Diagnosis – Elevated digital pulses – Heat in the hoof wall – Focal pain response to hoof testers – +/- Palmar digital nerve block – Find tract – +/-Radiographs Subsolar Abscess Treatment – Drainage!!! Don’t be overzealous Remove necrotic debris – NSAIDS – Antibiotics??? – Clean foot environment Subsolar Abscess Treatment – Poultice until infection resolved – Then dry bandage – Analgesia – 2-3 days – Tetanus prophylaxis!!! Subsolar Abscess Prognosis – Excellent for simple – Significant improvement in lameness once drainage established. CORNS AND BRUISED SOLES Corns and Bruised Soles Corn: Solar bruise at the angle of the bar and the wall Bruise: rupture of blood vessels in the dermis under sole, frog, or hoof wall Solar Bruises Clinical Signs Etiology Trauma to the sole – Rough/hard ground conditions – Pressure from improper shoeing – Poor confirmation (flat soles, under run heel with long toe) Variable lameness – Unilateral or bilateral Focal areas of hemorrhage – Often obscured by pigmentation Pain on palpation or hoof testers Solar Bruises Treatment Diagnosis Visual Inspection – Lightly debride sole with hoof knife Palpation/ Hoof testers Perineural anesthesia Radiography Remove source of trauma Avoid hard surfaces Appropriate trimming/ shoeing – Protect hoof from future trauma – Discourage excessive paring NSAIDS PEDAL OSTEITIS Pedal Osteitis Definition: Inflammation of distal phalanx Remodeling/ Lysis of solar margin Poorly defined disease – Radiographic diagnosis – Questionable correlation with clinical signs Pedal Osteitis Etiology Chronic inflammation of laminae Concussion Sole bruising Thin sole Mild laminitis Clinical Signs Lameness variable: worse on hard surface Pain on hoof testers Pedal Osteitis Diagnosis Radiography Treatment Eliminate primary problem Irregular solar margin Rest Proliferative dorsal surface Protect sole from concussion Perineural anesthesia Work on softer surfaces Scintigraphy Appropriate shoeing (increase surface area) Pedal Osteitis Puncture Wounds True Surgical Emergency – Career/life threatening injury – Referral to surgical facility immediately! – Especially frog and coronary band Nails, wire, wood, metal scrap Puncture Wounds Structures involved – Deep digital flexor tendon and tendon sheath – Coffin joint – Navicular bone and bursa – Coffin bone Smith, Eq Vet Ed, 2013 Puncture Wounds Clinical Signs – Lameness varies from mild to severe – Chronic are often severely lame – Effusion Coffin joint Tendon sheath Puncture Wounds Diagnosis – Examination and inspection of the foot – Radiography Leave object in place Lateromedial and 0° DP Contrast studies – Pressurize synovial structures Puncture Wounds Treatment – On the farm +/- remove foreign body (radiographs first!!) Clean foot Debride wound Bandage Refer Puncture Wounds Treatment – Antimicrobials Systemic Regional limb perfusion Synovial infusion system – Tetanus prophylaxis – NSAIDS Puncture Wounds Surgical Treatment – General Anesthesia – Arthroscopy/Tenoscopy/Bursoscopy (assessment and lavage) – Streetnail Procedure Puncture Wounds Streetnail Procedure Tenoscopy/Bursoscopy Puncture Wounds Treatment – Cast – Bandage – Treatment Plate www.thehorse.com www.barefoothooves.net www.hoofwork.com Puncture Wounds Prognosis – Guarded-Fair for life – Guarded/poor for athleticism – Prognosis should be reserved until response to treatment is observed – Hindlimb > Forelimb – Early intervention is ideal Puncture Wounds Arthroscopic debridement is the treatment of choice – 63% return to athletic function – 75% owner satisfaction Streetnail procedure has fallen out of favor – 68% unsatisfactory outcome in one study NAVICULAR SYNDROME Lameness caused by pathology of? Navicular bone Navicular bursa Impar ligament Navicular suspensory ligament (CDSL) DDFT in foot region Diagnosis History and clinical findings Localization using local analgesia Radiographic findings Nuclear scintigraphy Ultrasound MRI/CT Clinical Signs Forelimb lameness – often bilateral Lameness often worse when turning Lameness often worse on hard surface Clinical Signs “Pointing” or stumbling Clinical Signs Foot shape/ conformation Broken back Hoof-Pastern Axis Clinical Signs Foot shape/ conformation Contracted Heels Clinical Signs Foot shape/ conformation Low/Weak Heels Clinical Signs Across heels Across frog Each heel Hoof testers – often equivocal Over mid-frog Clinical Signs Lower Limb Flexion Test – often positive Clinical Signs Wedge test Diagnosis History and clinical findings Localization using local analgesia Radiographic findings Nuclear scintigraphy Ultrasound MRI/CT Diagnostic Analgesia Palmar Digital Distal Interphalangeal Navicular Bursa Abaxial Sesamoid Lameness - Navicular Disease Baseline lameness on the lunge Lameness - Navicular Disease Lungeing following PDN block of LF Diagnosis History and clinical findings Localization using local analgesia Radiographic findings Nuclear scintigraphy Ultrasound MRI/CT Pathology and Radiology Dorsoproximal-palmarodistal 60 degree oblique - Normal Radiographic Navicular Disease Medullary lysis / cyst formation Palmaroproximal-palmarodistal oblique - Normal Radiographic Navicular Disease Flexor cortex – 40x H&E Flexor cortex roughening Radiographic Navicular Disease Medullary sclerosis / poor demarcation with cortex Medulla – 100x H&E Radiographic Navicular Disease Medullary lysis / cyst formation Lateromedial - Normal Radiographic Navicular Disease Medullary lysis / cyst formation Radiographic Navicular Disease Medullary lysis / cyst formation - CT Radiographic Navicular Disease Enthesiophyte formation at insertion of Nav. Susp. Ligg. Radiographic Navicular Disease Mineralization within the DDFT Radiographic Navicular Disease Distal border synovial invaginations - variable Radiographic Navicular Disease Distal border synovial invaginations - variable Diagnosis History and clinical findings Localization using local analgesia Radiographic findings Nuclear scintigraphy Ultrasound MRI/CT Nuclear Scintigraphy Diagnosis History and clinical findings Localization using local analgesia Radiographic findings Nuclear scintigraphy Ultrasound MRI/CT Ultrasound of the Navicular Region / DDFT Diagnosis n n n n n n History and clinical findings Localization using local analgesia Radiographic findings Nuclear scintigraphy Ultrasound MRI/CT MRI / CT Useful to image within hoof capsule Differential Diagnoses Navicular disease Similar foot lameness Nav bursitis DIPJ collateral desmitis Nav bone pain/edema DDF tendinitis DDAL desmitis Cyst of the P2/P3 Nav. Susp. Desmitis DIPJ osteoarthritis Impar ligament desmitis PIPJ osteoarthritis Adhesions DDFT/bone Distal sesamoidean desmitis Combination injuries Treatment Correct shoeing – Reduce forces on navicular bone / heels – Balance the foot – Correct / reduce conformational faults – Ease breakover forces Rolled toe, raised heels Shoeing Treatment Controlled exercise program Change in career Treatment Pain control – Analgesic – NSAID most commonly – Intra-bursal / intra-articular– HA/CCS – Extra-corporeal shock wave therapy – Tiludronate – PSGAG’s / IV hyaluronic acid Surgical Treatment Navicular Bursoscopy Desmotomy of navicular suspensory ligg Inferior check ligament desmotomy Extracorporeal shockwave therapy Surgical neurectomy Prognosis Poor for return to athletic soundness if lameness > 6 months Fair - good for return to soundness if lameness < 6 months Poor for multiple lesions on MRI Poor for severe pathologic radiographic lesions Management is the key Fractures of the Distal Phalanx Clinical Signs Etiology Acute, severe lameness Trauma +/- Increased digital pulses – – – – High speed impact- racing Standardbreds Paddock injury Kick solid object Penetrating wound Pain on hoof testers Articular fractures – Effusion of coffin joint Diagnosis Classification History and clinical signs Type 1-6 Radiography Articular vs. Non-articular Nuclear Scintigraphy Fractures of the Distal Phalanx Clinical Signs Etiology Acute, severe lameness Trauma +/- Increased digital pulses – – – – High speed impact- racing Standardbreds Paddock injury Kick solid object Penetrating wound Pain on hoof testers Articular fractures – Effusion of coffin joint Diagnosis Classification History and clinical signs Type 1-6 Radiography Articular vs. Non-articular Nuclear Scintigraphy Classification of P3 Fractures Type 1 Type 4 Non-articular Common Type 2 Articular Most common P3 fracture Type 5 Type 3 Multifragment Severe lameness Poor prognosis Articular saggital Uncommon Articular Extensor process Forelimbs Common Type 6 Solar margin Common + underdiagnosed Classification of P3 Fractures Type 1 Type 4 Non-articular Common Type 2 Articular Most common P3 fracture Type 5 Type 3 Multifragment Severe lameness Poor prognosis Articular saggital Uncommon Articular Extensor process Forelimbs Common Type 6 Solar margin Common + underdiagnosed Radiography of Distal Phalanx fractures NOT immediately obvious Repeat views in 10-14 days if suspect fracture but not visible at presentation KEY POINT Type 4 – Extensor process Type 2 and 3 fractures Distal Phalanx Fracture type 2 June 2010 October 2011 Distal Phalanx Fracture Type 5 Treatment of P3 Fractures Non-articular fractures Prevent expansion of hoof wall Bar shoes with clips Rim shoe Fiberglass casting tape Rest Treatment of P3 Fractures Articular Fractures Conservative § Prevent hoof wall expansion § Rest Internal fixation § Lag screw § Reconstruction of articular margin Prognosis of P3 Fractures Generally good Failure to reconstruct articular surface decreases prognosis – OA Healing time prolonged – 6-12 months convalescence May not heal radiographically Fractures of the Navicular Bone Etiology Clinical Signs Trauma Pathologic fracture Acute severe lameness Sensitive to hoof testers Chronic lameness increases by exercise § § Infection Chronic navicular syndrome Diagnosis Perineural anesthesia Radiography Fractures of the Navicular Bone Treatment Prognosis Rest Prevent expansion of hoof capsule Bar shoe with clips Neurectomy for chronic lameness Heel wedge- reduce DDFT pressure on navicular Surgical fixation – lag screw Poor Uncommon Questions?