Lecture 6: Disorders of the Equine Foot

PE focusing on the foot

• look for changes in color, odor, consistency of the hoof

• clean the sole and examine the entire foot

• flex and extend the foot

• use hoof testers

• observe the horse walking and trotting

• hoof shape and balance

• current state of trimming and shoeing

• wear of hoof

what would make hoof cracks significant?

if it involves sensitive lamina vs insensitive

what would make a digital pulse significant?

increased or bounding

diagnostics for the foot

• nerve blocks → localize the pain to the foot, PD or abaxial nerve block

• radiographs → plain films, contrast studies

• nuclear scintigraphy

• CT

• MRI

thrush =

infection of the frog

white line disease =

infection in the white line aka seedy toe

mixed infections

• aerobic

• fungal

• anaerobic → fusobacterium necrophorum

what is this?

thrush

what is this?

white line disease

etiology of thrush and white line disease

• moisture

• poor hygiene

• poor hoof care

• reduced weight bearing

• immunocompromised

what is this?

thrush (the frog)

what is this?

white line disease

clinical signs of thrush/WLD

• smell

• hoof abnormalities

• lame only with severe case

treatment of thrush/WLD

• improve hoof care and stall hygiene

• debride damaged tissue

• copper naphthenate

• iodine foot soak

what is this showing?

gas with WLD

canker

• common in draft horses

• chronic inflammation and proliferation

• hypertrophy of the sensitive lamina, degeneration of the superficial horn

• looks like granulation tissue

• cause is unknown

what are these showing?

canker

diagnosis of canker

• ± mild lameness

• soft, greasy, friable, proliferative tissue over frog

• characteristic smell → yeasty

• can affect multiple hooves

treatment for canker

• surgical debridement

• local antibiotics (metronidazole)

• liquid nitrogen

• owner compliance → months of treatment

• can’t always cure!

what is this?

canker

subsolar bruising etiology

• thin-soled horses

• wet conditions

• rocky ground

what is this?

subsolar bruising

corn

• special area of sole bruise at angle of sole

• usually from overdue shoeing

what are these?

corn

diagnosis of subsolar bruising

• variable lameness

• worse on rocky ground

• positive to hoof testers → diffuse, squishy sole

treatment for subsolar bruising

poultices, shoes, keep out of mud

what is one of the most common causes of severe lameness in horses?

subsolar abscess

etiology of subsolar abscess

• wet conditions

• keratoma

• sequel to a bad bruise

• puncture wound

• nail from shoe → quicking, pricked, close or blind

• bacteria enter through failed hoof barrier

• pus accumulates → pressure → pain

what is this?

subsolar abscess

subsolar abscess may break out at

the coronet or heel → reduced lameness, still want to establish ventral drainage if possible!

what is this?

subsolar abscess breaking out of coronet and heel

what is the goal of subsolar abscess?

draining

diagnosis of subsolar abscess

• acute onset, severe lameness

• increased digital pulse

• possible distal limb swelling

• squishy spot at coronet

• + hoof testers over area of abscess

• gas pockets on radiographs

what are these showing?

subsolar abscess gas pockets

treatment of subsolar abscess

• pain relief

• tetanus toxoid vaccine

• pare out abscess → ventral drainage

• soak foot

• poultice foot

• protect foot

poulticing feet

• reduce inflammation → hyperosmotics, DMSO, clay poultice, animalintex

• harden hoof → hyperosmotics, tincture of iodine, keratex

distal hoof wall defects

• failure of hoof strength

• usually superficial → not a cause of lameness

• painful if down to sensitive tissues

proximal hoof wall defects

• trauma to the coronary band

• usually painful

what is this?

distal hoof wall crack

what is this?

proximal hoof wall crack

floating crack and widen crack

• mostly at heel and quarters

• reduce weight bearing and shear on crack

what is this?

floating crack

notch to halt propagation

mostly where floating isn’t feasible (aka the toe)

what is this?

notch to halt propagation

what is this?

heel crack

penetrating wounds to the sole

• do not take objects out until after rads

• if it does get pulled out before you take rads, try contrast radiography

• if involves synovial structure, follow rules for diagnosis and treatment as for septic arthritis

treatment for penetrating wounds to the sole

• early, aggressive treatment necessary

• broad spectrum antimicrobials

• local antimicrobials → intrasynovial, regional limb perfusion

• NSAIDs

• tetanus toxoid

• clean and disinfect the sole and tract standing

if a penetrating wound involves a synovial structure =

refer!

surgical debridement under general anesthesia for penetrating wounds

• street nail procedure

• navicular bursoscopy

• flexor tendon tenoscopy

• coffin joint arthroscopy

what is this?

street nail procedure

street nail procedure aftercare

• keep clean → sterile bandages until granulation, hospital plate shoe

• continued lavages as needed

• antimicrobials and NSAIDs → several weeks

• prognosis → guarded

features of the distal phalanx (P3)

• acute, moderate to severe lameness → not usually fracture lame

• owners may or may not know of the traumatic event

• hoof tester sensitivity

• increased digital pulse

diagnosis of P3 fractures

• radiographs → if fracture line is not visible, re-radiograph in 7-10 days, often need obliques

• ± arthrocentesis of the coffin joint → helps differentiate between articular and non-articular fractures

• synovial fluid → blood tinged with articular fractures

• ± CT/MRI

treatment for type I, II, and III P3 fractures

• NSAIDs

• stall rest for 2-4 months

• stabilization of hoof capsule → foot cast, rim shoe

• may never form a boney union

• horse can be sound but radiographs still look the same

treatment for type III P3 fractures

• some surgeons recommend internal fixation

• may be advantageous with a step at the articular surface

• lots of complications

• sepsis!

treatment type IV P3 fractures

• arthroscopic or arthrotomy removal

• not all cause lameness

• buttress foot

what are these showing?

buttress foot → type IV P3 fracture

treatment for type V P3 fracture

• comminuted P3 fractures

• severe lameness

• poor prognosis for future soundness

• euthanasia is recommended

what is this showing?

type V P3 fracture

treatment for type VI P3 fracture

• solar margin fractures

• may occur because of chronic laminitis or trauma (pedal osteitis)

• removal only if necessary if septic

• most fractures heal, small fragments are resorbed

what is this?

type VI P3 fracture

prognosis for athletics after type I and II P3 fracture

• good to fair

• depends on amount of joint involvement for type 2

prognosis for athletics after type III P3 fracture

• fair

• depends on quality of reduction and subsequent coffin OA

prognosis for athletics after type IV P3 fracture

• good

• depends on amount of coffin OA

• can be incidental finding

prognosis for athletics after type V P3 fracture

guarded for life

prognosis for athletics after type VI P3 fracture

good

keratoma

abnormal thickening of the hoof wall → likely secondary to inflammation or trauma to the hoof, presses on P3 and causes remodeling

clinical signs of keratoma

• can cause distortion of P3

• recurrent subsolar abscesses

treatment for keratoma

• surgical removal of the abnormal tissue

• better prognosis than conservative management ?

what is this?

keratoma

what is this?

keratoma