Lecture 6: Disorders of the Equine Foot

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

- look at hoof shape, balance, cracks quality of shoeing and wear

- clean the sole and examine the entire foot

- flex and extend foot

- use hoof testers

- observe the horse walking and trotting

- digital pulse

What should you focus on when doing a physical exam focused on the foot?

- middle = cracked into sensitive tissues

- right = goes into coronary band and white line

Which of these hoof cracks is significant, since not all are?

- infection of the frog

What is thrush?

- infection of the white line (seedy toe)

What is white line disease?

- MOISTURE

- Poor hygiene

- Poor hoof care

- Reduced weight bearing

What are 4 etiologies of thrush and white line disease?

- Smell

- Hoof abnormalities

- Lame only with severe cases

What are the clinical signs of thrush and white line disease?

- Clinical signs

- Rads for white line disease to determine extend of dz

How do you diagnose thrush and white line disease?

- Improve hoof care and stall hygiene

- Debride damaged tissue

- Copper naphthenate

- Iodine

How do you treat thrush and white line disease?

- chronic inflammation and proliferation that results in hypertrophy of the sensitive lamina, degermation of the horn.

- Looks like granulation tissue.

- Common in draft horses

What is cranker?

- +/- mild lameness

- Soft greasy, friable, proliferative tissue over frog

- Characteristic smell of yeast

- Can be in multiple hooves

How do you diagnose Canker?

- Surgical debridement (may be excessive)

- Local abx (metronidazole)

- Liquid nitrogen

- Owner compliance

(can't always cure --- VERY frustrating)

How do you treat canker?

- Thin-soled horses (careful with hoof testers)

- Wet conditions

- Rocky ground (see lameness worsen when walking in these conditions)

What is the etiology for subsolar bruising?

- a corn

- special area of sole bruise at angle of the sole

- usually from overdue shoeing

This horse has subsolar bruising. What is this?

- Variable lameness that is worse on rocky ground (clinical signs)

- Positive to hoof tester; diffuse and squishy sole

How do you diagnose subsolar bruising?

- Poultices

- Shoes + walk on softer ground

- Keep out of mud

How do you treat subsolar bruising?

- subsolar abscess

This is one of the most causes of severe lameness in a horse. What is it?

- Wet conditions

- Keratoma (chronic abscess)

- Sequel to bad bruise

- Puncture wound

- Nail from shoe

What is the etiology of a subsolar abscess?

- bacteria enters through the failure in the hoof barrier

- pus accumulates

- pressure increases

- pain

How does a subsolar abscess lead to such severe pain?

- still need to establish a ventral drainage point if possible since there might be pus under the crack

Some subsolar abscesses can break out of at the coronet band or heal? How should they be drained?

- acute onset of severe lameness

- ++++++ HOOF TESTERS over area of abscess

- Increased digital pulse

- Possible distal limb swelling

- Radiographs if not 100% sure they are improving

How do you diagnose a subsolar abscess?

- Pain relief (phenylbutazone)

- Tetanus toxoid vaccine

- Pare out abscess *need ventral drainage*

- Soak feet if unable to open abscess

- Poultice foot (reduce inflammation and harden hoof)

- Protect foot depending on the environment

What are treatments for a horse with a subsolar abscess?

- fracture

- pedal osteitis (+/- septic)

If a subsolar abscess does not respond to treatment after a few days what other things should you look at?

- Due to failure of hoof strength

- Usually superficial and not a cause of lameness

- Painful if down to sensitive tissues

What are distal hoof wall defects like?

- Due to trauma to the coronoid band

- Very painful

What are proximal hoof wall defects like?

- Hoof testers

- Palpation

- Blocks

How do you diagnosis hoof cracks causing lameness?

- float cracks and widening cracks

- **** mostly at heel and quarters

- reduce weight bearing and shear on the crack

How do you want to treat this hoof wall crack?

- notch to halt propagation

- mostly when floating is not feasible (aka the toe)

How do you want to treat this hoof wall crack?

- Float and widen cracks

- Notch to halt propagation

- Dremal heel cracks

- Stabilize hoof wall

How can you treat hoof wall cracks?

- DIP joint

- flexor tendon sheath

- navicular bursa

- DDFT

There is a penetrating wound into over the palmar aspect of the navicular bone and into the synovial space. What structures of impacted?

- MUST BE DONE PRIOR TO TAKING OBJECT OUT, since you will never know where it went and penetrated into

- If you do remove the object, you may need to take contrast radiographs

How do you take radiographs of a hoof with a penetrating wound?

- Synovial structures follow rules for septic arthritis --> refer

- Early, aggressive treatment = necessary

- Broad spectrum abx

- Local antibiotics (intrasynovial or regional limb perfusion)

- NSAIDs!

- Tetanus toxoid (+/- antitoxin)

- Clean and defect the sole and tract standing

- Salvage procedure

How do you treat a horse with a penetrating hoof wound?

- Surgical debridement

- Street nail procedure

- Flexor tendon tenoscopy

- Coffin joint arthroscopy

What are the salvage procedure for a penetrating hoof wound?

- keep hoof clean with a bandage or hospital plate shoe

- continue lavage as needed

- antimicrobials and NSAIDs for several weeks

What is the after care for a street nail procedure like?

- Guarded, but depends on duration of clinical signs before treatment

What is the prognosis for a street nail produce?

- unknown etiology

- acute, moderate to severe lameness

- hoof tester sensitive

- increased digital pulse

What are fractures of the distal phalanx (P3) like?

- medial or lateral palmar processes (abaxial)

- non-articular

What is a type I P3 fracture?

- medial or lateral (abaxial)

- articular

What is a type II P3 fracture?

- axial

- joint involvement

What is a type III P3 fracture?

- involve the extensor processes

What is a type IV P3 fracture?

- comminuted and articular

- several fragments

- usually second to a penetrating FB, trauma or osteomyelitits

What is a type V P3 fracture?

- solar margin fracture

- non articular

(may occur due to chronic laminitis and trauma)

What is a type VI P3 fracture?

a. 6 (solar margin fracture)

b. 3 (axial fracture)

c. 4 (involves extensor processes)

d. 1 (abaxial - non-auricular)

e. 2 (abaxial - auricular)

f. 5 (comminuted and articular)

What are the types of P3 fractures?

- Radiographs (If fx not seen wait and retake in 7-10 days; often need obliques)

- +/- Arthrocentesis of the coffin joint

- +/- CT/MRI

How do you diagnose a P3 fracture?

- Helps determine is joint is involved or not

- If synovial fluid is blood tinged = articular fracture

Why might you do an arthrocentesis when trying to diagnose a P3 fracture?

- NSAIDs

- Stall rest for 2-4 months

- Stabilization of the hoof capsule (foot cast or rim shoe)

How do you treat Type I, III, and III P3 fractures?

- Might be advantageous if the articular surface is involved, but LOTS of complications

- SEPSIS

What are the pros and cons to doing a internal fixation which is done by some surgeons on a type III P3 fracture

- may never form a bony lesion (coffin bone fx never look fixed, all based on clinical signs)

- horse can be sound, but radiographs can still look the same

What are some things to remember when treating Type I, III, and III P3 fractures?

- Arthroscopic or arthrotomy removal, if is causing lameness

- Buttress foot

What is the treatment for a type IV P3 fracture?

- severe lameness

- guarded to poor prognosis

- euth recommended

What are type V P3 fractures like?

- Remove only if septic

- Most heal and small fragments are resorbed

What is the treatment for a type VI P3 fracture?

- good to fair

- based on amount of joint involvement for type 2

What is the prognosis for type I - II P3 fractures?

- fair

- depends on quality of reduction and subsequent coffin OA

What is the prognosis for type III P3 fractures?

- good

- depends on amount of coffin OA

What is the prognosis for type IV P3 fractures?

- good

What is the prognosis for type VI P3 fractures?

Abnormal thickening of the hoof wall

- Epidermal tumor?

- Likely secondary to inflammation or trauma of food

-Presses on P3 and causes remodeling

What is a keratoma? What is the possible etiology?

- Distortion of P3

- Recurrent subsolar abscesses --> lameness

What are the clinical signs of a keratoma?

- Surgical removal of the abnormal tissue, will make a better prognosis than conservative management

What is the treatment and prognosis for a keratoma?