Conditions of the Equine Foot

Question 1

What is the white line?

Answer 1

The junction between the sole and inner hoof wall

Question 2

What are the 4 signs of inflammation within the equine hoof?

Answer 2

1. Heat
2. Digital pulses
3. DIP joint effusion
4. Pastern oedema

Question 3

What is nail prick and nail bind?

Answer 3

Nail prick - nail of shoe gone through laminae

Nail bind - nail of shoe too close to laminae

Question 4

How do hoof cracks form and how can we treat them?

Answer 4

Mixture of poor horn quality, thin hoof wall and abnormal hoof angle

Suture/staple or apply a plate - prevent crack from splaying when loaded

Question 5

What is club foot?

Answer 5

Upright hoof/raised heel

Question 6

What is a keratoma?

Answer 6

Benign growth of hoof horn

Usually in the dorsal wall due to irritation or abscess

Cause pressure inside the hoof which can lead to pedal bone lysis, may need to removed the abnormal tissue

Question 7

What are thrush and canker?

Answer 7

Thrush - infection of the frog –> necrosis

Canker - deeper infection of frog and heel, see pus, pungent odour and bleeding –> disintegration of intertubular horn

Question 8

What is white line disease and how do we manage it?

Answer 8

Loss of bond between hoof wall and sole becomes colonised with bacteria and fungi, often secondary to laminitis or poor hoof quality

Management:
Debride all necrotic tissue and diseased horn
Disinfect environment
Bandage to protect laminae
Hardening solutions e.g. forulin

Question 9

What is a hoof abscess and how are they causes?

Answer 9

Infection of the laminae

• Nail too close
• Penetrating foreign body
• Sole bruise

Question 10

What is quittor?

Answer 10

Infection of collateral cartilage

Question 11

Name 2 causes of a black line in the navicular bone on radiography…

Answer 11

1. Fracture - could screw together, generally good prognosis but may get OA
2. Bipartite navicular bone - congenital abnormality where there were 2 centres of ossiciation

Question 12

Which structure could be involved in navicular syndrome and what is the typical clinical sign?

Answer 12

Navicular bone
Navicular bursa
DDFT
DIP joint
Collateral ligament of DIP joint

Toe first gait (reducing weight on heel)
Usually bilateral lameness
Responds to PD nerve block

Question 13

What are the 6 types of fractures of the distal phalanx in the horse and how would you treat them?

Answer 13

1. Wing (non-articular)
   Hoof cast, bar shoe ± lag screw
   6m box rest
2. Wing (articular)
   As above
3. Sagittal (migline)
   Lag screw, bar shoe
   3-12m box rest
4. Extensor process
   Distinguish from occasional separate centre of ossification often displaced by extensor tendon
   Remove fragment
   3-6m box rest
5. Comminuted
   Transfixation cast or euthanasia depending on severity
   4-6m box rest
6. Solar margin
   Bar shoe
   6m box rest

Question 14

What is the main complication of any fracture of the distal phalanx and how do we treat it?

Answer 14

DIP OA

Intraarticular sodium hyaluronate or steriods
NSAIDs
Corrective farriery

Question 15

How do you distinguish pedal osteitis and keratoma in the horse?

Answer 15

Pedal osteitis - chronic inflammation of the laminae leads to bone resorption, increased vascular pattern

Keratoma - thickening of hoof wall leads to compression and lysis of the pedal bone

Question 16

What are the problems associated with disease inside the horse hoof?

Answer 16

Inflammation cannot go anywhere - increases pressure within hoof causing more damage

Difficult to examine

Difficult to relate pain to specific structures

Question 17

What are the typical clinical signs of laminitis?

Answer 17

Resting with weight on heels, leaning back as the laminae at the front of the hoof are painful

Lameness affecting 2 or more limbs

Bounding digital pulse

Increased hoof temperature

Pain with hoof testers at the point of the frog

Palpable depression at the coronary band

Question 18

How would you prepare the equine foot for radiography?

Answer 18

Remove any dirt or stones

Remove loose horn

Place marker on dorsal hoof wall

Remove shoes if obscuring region of interest

Pack grooves with Play-Doh

Question 19

What radiographic view is best for:

a. Extensor process
b. Sole
3. Navicular bone

Answer 19

a. Lateromedial
b. Dorso-60-proximal palmarodistal oblique
c. Dorso-60-proximal palmarodistal oblique for articular surface, palmaro-45-proximal palmarodistal oblique for flexor surface (skyline view)

Question 20

What is a crena?

Answer 20

Notch or cleft in the solar margin of the pedal bone

Question 21

What are the 6 radiography signs of laminitis?

Answer 21

1) Dorsal hoof wall and dorsal distal phalanx not parallel, if angle >15º poorer prognosis
2) Distance between coronary band and extensor process of distal phalanx (founder distance) >13mm indicates sinking
3) Dorsal hoof wall thickness >3cm indicates chronic laminitis
4) Lucent line in dorsal hoof wall
5) Lucent line at coronet (sinking)
6) Remodelling or fracture of solar margin (chronic)

Question 22

What is the difference between an osteophyte and entheseophyte?

Answer 22

Osteophyte - projection into joint space

Entheseophyte - projection at site of ligament or tendon attachment

Question 23

What are the radiographic signs of navicular disease?

Answer 23

1) Entheseophyte formation
2) Loss of corticomedullary junction (sclerosis)
3) Flexor cortex erosions (lucency)
4) Abnormal distal border (fossae or fractures)

Question 24

What are the risk factors for laminitis?

Answer 24

1) Sepsis / systemic inflammation
- Can arise from GI disease, pneumonia, septic metritis

2) Endocrine disease
PPID, EMS

3) Mechanical overload
4) Access to pasture, particularly new grass (carbohydrate overload → systemic inflammation)
5) Ponies
6) Female
7) Age
8) Obesity

Question 25

How can inflammation lead to laminitis?

Answer 25

Dysregulation of epithelial adhesion molecules (hemidesmosomes)

MMP activation (protease enzymes)

Question 26

Which group of animals are most at risk of pasture associated laminitis?

Answer 26

Obese

EMS

Summer pastures contains more carbohydrates exaggerating insulin resistance

Question 27

What is the treatment of laminitis?

Answer 27

Analgesia - NSAIDs, opiates in hosp

Foot support - Increase bedding, apply bandages, lilypads

ACP - vasoconstriction

Box rest - aided by ACP

High fibre, low concentrate diets

Treat underlying endocrine disorders