Hoof Capsule and Distal Phalanx

The white line is the junction between what two structures?

Sole and hoof wall

What do we call the deterioration of the white line of the hoof capsule?

White line disease

White line disease is incited through the presence of —————, which allows the colonization of different bacteria and fungi.

Poor-quality horn

What climate is white line disease more common in?

Warm and humid

True or False: A higher prevalence of white line disease was encountered with less frequent hoof picking, use of flax bedding, white-colored hooves, and longer intervals between trimming sessions.

True!

How can you visually diagnose white line disease?

Hoof wall begins to separate from the sole

How do you treat white line disease?

Remove altered/necrotic horn via debridement or resection and treat with same solutions used for thrush for anti-organismal coverage

Why should horseshoe nails be placed higher than normal in horses with white line disease?

Prolong duration shoe is firmly attached to sole

True or False: Nail holes and the underside of the cleats on a shoe should be sealed with bactericidal and fungicidal agents in a case of white line disease.

True!

What is the columnar-shaped thickening of the hoof horn that extends toward the inside of the hoof and composed of poor-quality horn?

Keratoma

T/F: A keratoma is a neoplastic process of the hoof.

False! A keratoma is NOT neoplastic

T/F: Most keratomas are found in the dorsal, dorsolateral, or dorsomedial aspect of the wall

True!

What clinical history might put a keratoma high on your list? Why?

Chronic recurrent hoof abscess

Keratoma causes decay and allow organisms to enter inside of hoof wall

What is thought to be the most common cause of a keratoma?

What is the other major cause?

Inflammation/trauma where new horn produced at coronary band and hoof wall -> scar tissue

Hoof abscess

What sequelae can develop from the pressure caused from a keratoma?

Inflammation/lysis of P3

What is necessary to recognize the abnormal configuration of the white line due to a keratoma?

How will it look if abnormal?

Trimming/cleaning sole

Lamellar horn replaced by tubular horn and scar tissue with displaced hoof wall

What is the best way to truly diagnose a keratoma?

Radiograph (circular lytic lesion)

What are the FOUR major differentials for a keratoma?

Calcified hematoma, fibroma, SCC, malignant melanoma

What is the best treatment for a keratoma?

Surgery

What TWO principle ensure a successful outcome for a keratoma surgery?

1. Complete resection

2. Hoof wall support

Describe a keratoma surgery like a first grader.

Block it -> tourniquet -> drill hoof and curette out

How long should a horse be rested following keratoma surgery?

4-6 weeks

What is appropriate hoof support following keratoma surgery?

Shoe with large clips

True or False: Surgical treatment is better (83%) than medically managing a keratoma (43%) and has a very good prognosis for returning to work and soundness.

True!

T/F: Complete hoof wall resection from the coronary band to the sole has a greater complication rate than partial wall resection. Therefore, the hoof wall should be preserved by creating minimal hoof wall defects to provide stability to the hoof capsule.

True!

What is the most frequently diagnosed causes of lameness in equine practice that is occasionally misdiagnosed as a fracture?

Acute hoof abscess

What causes a hoof abscess?

Penetrating bacteria across hoof wall (usually from sole bruise)w

Where in the hoof does infection develop with an abscess, causing the accumulation of purulent material inside the hoof capsule?

Sensitive laminae

T/F: An abscess can often present as severe pain and non-weight-bearing lameness since the hoof acts like an external shield.

True!

What FOUR physical exam findings are consistent with a hoof abscess?

1. Increased hoof wall warmth

2. Positive on hoof testers

3. Strong digital pulse

4. Distal limb swelling

What nerve block is best to localize the hoof due to an abscess?

Abaxial sesamoid

What is the best way to diagnose a hoof abscess?

Radiograph (gas pockets)

An abscess that breaks out of the coronary band is called —-.

Gravel

Name THREE major steps to treating a hoof abscess.

1. Remove shoes and nails

2. Removed necrotic material

3. Iodine soak or poultice bandage overnight

Why should minimal NSAIDs be given to a horse with an abscess?

Suppress inflammation and make harder to localize abscess

Once an abscess is opened, the infected area is cleaned with ———————— and the bandage is changed every ——— days until dry. At this point, the horse can be reshod with a pad underneath.

Iodine or H2O2

2-3 days

What can happen if an abscess is not managed properly or in a timely fashion?

Break through coronary band or extend deeper into foot

How should you treat a horse with a deep abscess or one ruptured through the coronary band? (2)

1. Create window in hoof wall to open draining tract at coronary

2. Flush tract with iodine daily proximal to distal (exits sole)

What THREE aftercare steps should be taken after draining an abscess?

1. Bandage/treatment plate

2. Allow keratin formation

3. Re-shoe

T/F: An abscess can take weeks to heal, but generally only need antibiotics if deeper structures are involved.

True!

What is abnormal horn proliferation that occurs most frequently in the frog region?

Canker

T/F: Canker is neoplastic

False! Canker is a chronic inflammatory reaction with parakeratosis.

In canker, the sensitive laminae —- and the superficial horn and corium —-.

Hypertrophy

Degenerate

T/F: Canker can spread from the frog to the sole or even the hoof wall.

True!

Canker is most common in —- horses and the (forelimbs/hindlimbs) are most affected.

Draft

Hindlimbs

What are the TWO most common possible etiologies of canker?

1. Long-standing thrush

2. Unsanitary stalls

What are TWO major differentials for canker?

1. Advanced thrush

2. Fungal infection of coronary band

T/F: Spirochetes, Treponema, and bovine papilloma virus have all been investigated as possible causative agents of canker.

True!

What kind of bacteria seem to be the most important contributors to canker?

Gram negative anaerobes

What are FOUR indicators of canker on physical exam?

1. Cauliflower-like growth not cornified at surface and covered with greasy, whitish material

2. Foul odor

3. Painful to pressure/lame

4. Bleeds profusely when traumatized

What is the initial treatment for canker?

Surgical debridement

When debriding canker, removing the abnormal horn while sparing the ————— is essential.

Stratum germinativum

What tool can help you determine the transition from abnormal to healthy hoof horn?

Hoof knife

T/F: After surgical debridement of canker, a new frog grows within a few months and is bandaged during this time. The treatment is labor-intensive and time-consuming.

True!

The entire —- is usually removed when debriding canker in a horse.

Frog

After surgical debridement, how do you medically manage a canker? (4)

1. Iodine bandages for 2-3 days

2. Drying agent/disinfectant/astrignent (iodine + zinc + metro)

3. Systemic antibiotics (if >1 hoof)

4. Pred (canker thought to be autoimmune if >1 hoof)

Systemic antibiotics include —— and —— for canker if needed. Local and systemic treatment with —- and —— has also been recommended.

Chloramphenicol

Metronidazole

Doxycycline

Oxytetracycline

Reported success rates for an acceptable long-term outcome of canker varied from —- to —-%.

75% to 85%

What is required to be repeated in most cases of canker?

Surgical debridement

Name FOUR common causes of P3 fracture.

1. Acute trauma

2. Fast/excessive work

3. Kick to hard, unmoving object

4. Laceration of hoof capsule

Are the forelimbs or hindlimbs more commonly involved in P3 fracture?

Forelimbs

Describe the SIX classifications of P3 fracture.

I: abaxial/paramedian without joint involvement

II: abaxial/paramedian with joint involement

III: axial and periaxial fractures with joint involvement

IV: fractures of extensor process

V: multifragment/comminuted fractures with joint involvement

VI: solar margin fractures

T/F: Some complicated fractures involve several fracture types and therefore cannot be classified as one type.

True!

What are THREE common clinical signs of P3 fracture?

1. Acute, moderate to severe lameness worse when turning

2. Hoof and P3 region warm to touch

3. Increased digital pulses

What kind of synovial fluid would you expect with centesis of a P3 joint when fractured?

Blood-tinged

What indicates fracture on radiograph?

Thin lines crossing vascular channels at different angles

If you suspect a fracture but cannot see it radiographically, what should you do?

Keep in box stall and repeat rads 7-10 days to allow for enlargement of fracture gap

T/F: A single lateral view is usually diagnostic for a P3 fracture.

False! Multiple views should be taken, especially from multiple oblique angles.

How can you treat a Type 1 P3 fracture? (2)

1. Fiberglass cast on hoof capsule for 2 months with sole filled with silicone to impede hoof capsule movement

2. Bar shoe with large side clips (limit hoof expansion during loading)

How long is stall rest required for a Type 1 P3 fracture?

2-4 months

What is the prognosis for a Type 1 P3 fracture?

How long does it take to fully heal?

When is the horse usually rideable again?

Reasonable

4-6 months

4 months

T/F: A fracture line is visible for much longer than its healing time.

True!

How do you treat Type II and III P3 fractures?

Screw fixation using lag technique of distal phalanx

Why is a screw fixation preferred over medical management of a Type II or III P3 fracture? (3)

1. Improved fracture reduction/stabilization

2. Hastens fracture healing

3. Reduced OA of DIP joint

When fixing a Type II or III P3 fracture, good —- technique is an indispensable prerequisite for a successful operation and therefore a —- is required in the surgery.

Imaging

CT