12: Equine Digit

What is required of a foot for maximal performance

Perfect balance

T/F: it only takes a slight imbalance to cause a lameness

True

How should a foot hit when looking from the lateral plane

Flat or slightly heel first

How should a foot hit when looking from the frontal plane

Lateral first

What determines whether you should shoe your horse

• Performance

• Regular ground surface

• Hoof quality

Most significant aspect of shoeing a horse

The hoof trim

How far back should a shoe extend and why

All the way to the widest part of the frog in order to provide adequate heel support

What should you NOT do to the ends of the shoe

Curl them over or cut them off

T/F: if a horse is pulling shoes it is because the back of the shoe is too long and needs to be cut off

NO, it means their toe is likely long

How far out should a shoe extend and why

A few mm outside of the wall because the hoof and frog expands

Where is it appropriate to place nails

1 cm above the shoe, up to the widest part of the hoof, but not behind that

Shoe “web”

The width of the shoe

Materials shoes may be made out of

• Steel

• Aluminum

• Titanium

• Synthetic

Ways a shoe may be secured to a foot

• Nails

• Clips

• Glue

T/F: appropriate trimming and shoeing will prevent all MSK injuries

Haha, try again

Most common cause of severe (4-5/5) acute lameness

Subsolar abscess

Common history that often precedes a subsolar abscess

Horse was shod in the last 1-2 weeks

What might the presenting complaint be for a subsolar abscess

Fracture

PE findings consistent with a subsolar abscess

• Heat in the foot

• Focally positive to hoof testers

• Dark spot/tract at the solar surface

Treatment for a subsolar abscess

• Establish ventral drainage

• Poultice or soak to pull fluid

• Tetanus toxoid

• NSAIDs

• ± Remove shoe/nail

• ± Antibiotics

Why is it important to establish ventral drainage for a subsolar abscess

If you don’t give it a place to go, it will decide the path of least resistance and bust out the coronary band

Thrush

General term for a bacterial infection of the frog and solar surface

Factors that predispose a horse to thrush

• Muddy, wet conditions

• ± Hoof shape

Bacteria that commonly causes thrush

Fusobacterium necrophorum

Diagnosis for thrush

Foul odor and brittle, black solar surface when debrided

Why is it important to treat thrush

Infection can spread to the digital cushion and coffin bone

Treatment for thrush

• Debride abnormal tissue

• Keep foot dry

• Daily antiseptic

• ± Bandage and NSAIDs if deep

Ideal antiseptic for thrush and caution

Iodine; don’t use it on the coronary band!

White line

Distal most extension of the lamina

White line disease

Progressive separation of the non-pigmented laminar horn of the hoof wall and stratum medium of the lamina

Most common area affected by white line disease

Toe or quarters

Diagnosis of white line disease

Typically visual diagnosis

T/F: white line disease causes lameness

Not really

When might a horse with white line disease be lame

If it is preceded by laminitis or if the hoof wall breaks off

Predisposing factors for white line disease

• Long toes

• Club feet

• Laminitic feet

• Toe abscesses

• Quarter cracks

• Unsanitary stall

Prevention for white line disease

Proper and timely foot trimming and clean environment

Treatment for white line disease

• Aggressive debridement

• Topical antiseptic

• Keep environment clean

• ± Hoof wall resection, sole support

Prognosis for white line disease

Typically an easy fix with good prognosis

Type of bone that makes up P3

Mostly cancellous bone, doesn’t really have cortical bone

T/F: P3 has a medullary cavity

False

Normal P3 margination

Typically has a slight feathered edge

Causes of P3 osteitis

• Poor foot balance and shoeing

• Chronic solar trauma

• Laminitis

• DIP flexural deformity

Radiographic changes consistent with P3 osteitis

• Bone resorption → more dramatic feathered edge

• Widened vascular channels

Treatment for P3 osteitis

• Proper shoeing: maintain palmar angle

• Rest

• NSAIDs

Treatment that may be indicated for severe P3 osteitis

Distal inferior check desmotomy to relieve some pull from the DDF

Prognosis for osteitis

Good

Causes of septic osteitis

Penetrating injury or deep subsolar/laminar abscess

T/F: if a client calls with a horse that stepped on a penetrating object, they should remove that object before coming to you

FALSE

Degree of lameness associated with septic osteitis

Can be quite severe, or less lame if there is a draining tract

Diagnostic for septic osteitis

Radiographs

Radiographic findings associated with septic osteitis

Lysis and remodeling

Treatment for septic osteitis

• Surgical debridement/curettage

• Regional limb antibiotic perfusion

• Poultice/soak

Prognosis for septic osteitis

Pretty good if you get to it before the coffin joint

CS of P3 fracture

• 2-5/5 lameness

• Heat and digital pulse

• Positive to hoof testers

Diagnostics for P3 fracture

60-65 degree DP view or CT

Radiographic findings consistent with an acute P3 fracture

Narrow space between bone fragments

Radiographic findings consistent with a chronic P3 fracture

Wider space between bone fragments as it heals with fibrous tissue

Treatment for P3 fracture types 1-3 and 5

• Immobilize, use the hoof capsule to make a cast

• ± Screw

• Neurectomy in the short term

Why is it hard to fix P3 fractures with a screw

P3 is mostly cancellous bone, which doesn’t hold screws well

Treatment for P3 fracture type 4 (extensor process fx)

Removal of the fragment