Anatomy of the Hoof

Question 1

What are the 9 functions of the hoof?

Answer 1

• Protection
• Support
• Weight distribution
• Traction
• Shock absorption
• Blood circulation

(Secondary)
- Tools
- Sensory organs
- Weapons

Question 2

What is the weight distribution in the horse leg?

Answer 2

P2 -> P3 -> laminae -> hoof wall -> ground

Question 3

What is the distal phalanx composed of?

Answer 3

• Hoof wall: inner & outer
• White line
• Frog
• Bones
• Nerves
• Venus plexus

Question 4

What is the outer side of the hoof composed of?

Answer 4

• Hoof wall
• Coronary band
• Periople
• Inner wall

Question 5

What is the underside of the hoof composed of?

5 structures

Answer 5

• bulbs of the heel
• bars
• sole
• frog
• white line

Question 6

What is the inner side of the hoof composed of?

Answer 6

• Bones
• Cartilage
• Tendons
• Ligaments

Question 7

What is the very tough vascular structure that sits at the top of the hoof wall?

Answer 7

the coronary band

Question 8

What are the 2 major functions of the coronary band?

Answer 8

• it produces the tubules of the outer hoof wall
• it acts as a band of support to add strength to the internal structure as the hoof distorts during the stride

Question 9

What is corium?

Answer 9

Any portion that has sensitive parts
(also called sensitive laminae, lamina, or dermis)

Question 10

What are papillae?

Answer 10

Structures on the sensitive lamina that project into the cavities of the hoof side to provide blood and nerve supply, as well as nutrients to the hoof.

Question 11

What is the area underneath (below) the coronary band that produces hard tissue? It is not as tough as the tissue of the coronary band. Similar to the cutile for horses.

Answer 11

Periople

Question 12

What is laminitis of the hoof?

Answer 12

Laminitis is an acute, painful and potentially debilitating condition affecting the hooves of horses, characterized by inflammation of the laminae—the soft tissue structures that connect the hoof wall to the coffin bone.

Question 13

What is the difference between founder and laminitis?

The acute phase is _______ and when the physical changes happen it is _________.

*All founder starts as laminitis but not all laminitis develops into founder.

https://youtu.be/ZGnJopVJsTo

by Dr. Lydia Gray, SmartPak Equine

Answer 13

Laminitis is the acute situation and founder is chronic laminitis, especially once some mechanical changes have occurred in the foot. Like the rotation or the sinking that you hear about.

There are 3 stages:
1) Developmental, injury to the laminae (few hours to days)
2) Acute phase, 1st time signs appear to about 72 hours, (about 3 days)
3) Chronic phase, 72 hours on, or when physical changes occur.
*X-rays show the coffin bone pulling away from the hoof wall, the sinking.
*Or even worse, the whole coffin bone just sinks to the bottom. So this is a rotation and this is sinking.

Question 14

What are 9 common hoof problems?

(video links below)

https://www.smartpakequine.com/learn-health/common-horse-hoof-problems

Answer 14

1) Laminitis and founder.
2) Thrush
3) Quarter cracks
4) Hoof bruise
5) Hoof Abscess
6) White line disease
7) Navicular syndrome
8) Canker
9) Club foot

https://www.smartpakequine.com/learn-health/club-foot-horse

Question 15

How are hoof or quarter cracks formed?

Answer 15

Caused by changes in hydration, conformation, and balance. They are linear cracks in the hoof.

Question 16

What is a hoof bruise?

Answer 16

It can be caused by overexerting itself or can be caused by injury, like kicking at the gate. Don’t confuse with laminitis and ignore it.

Question 17

5) Hoof Abscess

Question 18

White line disease

Question 19

7) Navicular syndrome

Question 20

Describe a hoof canker:

https://www.smartpakequine.com/learn-health/equine-canker

Answer 20

AKA hypertrophic pododermatitis or proliferative pododermatitis. It is an overgrowth of hoof horn tissue on the bottom (solar) surface of the horse’s foot.

It is generally considered to initiate with a bacterial, fungal, and/or viral infection resulting in a rapid proliferation of long fronds of keratin, the primary component of the hoof.

Question 21

9) Club foot

Question 22

Why is the horn material soft in the early stages?

Answer 22

to prevent the coronary band from being bruised by shock being transferred upwards through the hoof wall during the weight-bearing phase of the stride

Question 23

What are the 3 layers of the hoof wall?

Answer 23

• External layer (stratum externum)
• Middle layer (stratum medium)
• Internal layer (stratum internum)

Question 24

What are the parts of the hoof wall?

Answer 24

• dorsal part/toe (pars dorsalis)
• sides/quarters (pars lateralis et medialis)
• heels (pars mibilis lateralis et medialis)
• bars (pars inflexa lateralis et medialis)

Question 25

The outer wall is pigmented and contains a higher ratio of _____.

Answer 25

tubules

Question 26

How does a healthy hoof wall look?

Answer 26

- slightly thicker at the toe - no growth rings or cracks

Question 27

The hoof outer wall also regulates the output or input of ________.

Answer 27

moisture

Question 28

What color is the inner wall of the hoof?

Answer 28

white

Question 29

What is the function of the inner wall?

Answer 29

To help the hoof wall stretch and the moisture protects inner structures from shock.

Question 30

What causes hoof rings?

Answer 30

1) laminitis 2) nutritional changes 3) stress 4) trauma

Question 31

What is the hard surface of the hoof, similar to the human fingernail?

Answer 31

the horn

Question 32

What produces the cells that form the horn?

Answer 32

corium - it contains many blood vessels and nerves

Question 33

What is the white line (zona alba) of the hoof?

Answer 33

It is golden-colored line that joins the sole to the inner wall of the hoof. It creates a shallow crease at the bottom of the hoof, which fills with dirt, and aids with traction.

Question 34

What is the function of the white line of the hoof?

Answer 34

It is to seal off the border of the pedal bone to protect it from bacterial infiltration; it aids in traction

Question 35

What is the landmark that is between the sensitive and insensitive parts of the hoof?

Answer 35

the white line

Question 36

In white line disease, the hoof is quite ___________?

Answer 36

powdery

Question 37

What is the area inside the white line called (not including the bars and frog)?

Answer 37

sole

Question 38

What is the function of the sole?

Answer 38

1) protect the sensitive structures beneath the sole 2) the outer perimeter provides support and shares from of the weight

Question 39

Which sides of the hoof are sensitive and insensitive?

Answer 39

1) leg side (sensitive) 2) hoof side (insensitive)

Question 40

What happens during coffin bone rotation (founder)?

Answer 40

the coffin bone is displaced and pierces the sole, which damages it

Question 41

What is the "v"-shaped, triangular mass that lies between the bars of the foot and the heels, approximately 2/3 rd's of the sole, increases in thickness from front to rear?

Answer 41

frog

Question 42

Why is the frog soft and pliable, elastic?

Answer 42

It is made of approximately 50% water

Question 43

What are the parts of the frog called?

Answer 43

1) Point (apex) 2) Grooves along the sides (sulci) 3) Depression along the bottom surface (central sulcus or cleft)

Question 44

What is the function of the frog of the hoof?

Answer 44

1) expand and contract the heels of the foot as it moves 2) protects the digital cushion 3) traction for shock absorption

Question 45

What disease or infection affects the frog?

Answer 45

thrush - a common bacterial infection in horses that affects the frog of the hoof, characterized by a foul-smelling, black discharge and potentially causing lameness if left untreated.

Question 46

How often frog shed?

Answer 46

twice a year

Question 47

What happens if the frog doesn't do its job and the heels become contracted?

Answer 47

occur when the heels of the hoof shrink or move closer together, narrowing the heel area and potentially causing discomfort or lameness

Question 48

What is often called the "heart of the hoof"?

Answer 48

the frog, because its contraction and relaxation enables venous return of the blood

Question 49

How is the hoof supplied by blood?

Answer 49

There are 5 venous plexuses: (names correspond to what they do) 1) solar 2) digital cushion 3) lateral cartilage 4) lamellae 5) coronary

Question 50

Why would nerve blocking of the hoof be helpful?

Answer 50

To help locate, or confirm, the location of pain associated with lameness. In this case your veterinarian may begin by numbing the lowest structure on the leg and work their way up the leg.

Question 51

What are the 4 types of nerve blocks of the hoof? ## Footnote https://www.midriversequine.com/nerve-blocking-horse-lameness-exam/

Answer 51

Types of Nerve Blocks **Palmar Digital Nerve Block (Heel Block),** The block targets the back of the foot. It is injected over the palmar digital nerve just under the skin. It blocks the heel bulbs, frog, navicular bone, navicular bursa, the coffin joint, and the phalanx. **Abaxial Sesamoid Nerve Block** The block targets the **palmar nerve**: includes the medial and lateral palmer and the dorsal branch. The nerve runs along the back of the pastern. It blocks the deep digital flexor tendons in the foot, pastern joint and may numb portions of the fetlock joint. **Coffin Joint Block**, The block targets the **coffin joint**. It is placed above the coronet band on the front of the hoof. This block will numb the coffin joint. **Navicular Bursa Block** – This block targets the **navicular bursa** and is placed between the heel bulbs just above the coronet band. Radiographs are used to determine accurate placement. This block will numb the navicular bursa, supporting ligaments, the sole in the toe of the hoof and deep digital flexor tendon.

Question 52

What is an extension of the hoof wall that runs along the side of the frog, terminating half-way along the frog and is partially visible?

Answer 52

the bar

Question 53

What is the function of the bar?

Answer 53

1) control the movement of the back of the hoof 2) adding strength to the heel area 3) protecting it from excess distortion.

Question 54

Where is the collateral groove?

Answer 54

the groove that runs along either side of the frog between the bar and the sole.

Question 55

Where does the tendon of the deep digital flexor muscle attach?

Answer 55

semilunar crest of P3 (coffin bone)

Question 56

What is side bone of the hoof?

Answer 56

Hardening or ossification of the lateral cartilages on either side of the coffin bone

Question 57

Which bone of the hoof sits partially inside the hoof and just above the coronary band?

Answer 57

P2 (short pastern bone)

Question 58

Where is the navicular bursa and what is its function?

Answer 58

It is located posterior to the coffin bone and the synovial fluid is a cushion that lubricates the deep digital flexor tendon and navicular bone because the tendon slides during movement

Question 59

What bones do the T-lig and impar ligament attach to?

Answer 59

T-lig: DDFT, P2, navicular Impar: Navicular and coffin

Question 60

What is the digital cushion made of? Where is it located?

Answer 60

fibrocartilage and fat ; It is located between the frog and the heel bulbs

Question 61

What is the podotrochlear apparatus (PTA) consist of?

Answer 61

Navicular bone, T-ligaments, impar ligament, & DDFT

Question 62

What is deciduous horn shoe (eponychium)?

Answer 62

This is the soft, gelatinous membrane that covers the foal's hooves at birth to protect the uterus and birth canal from damage. It usually falls off or disappears by wearing away once the foal begins to stand. Other names are "fairy fingers" and "golden slippers" or "horse fingers".

Question 63

What is the ergot / night eye above the knee in the forelimb on the inner side and below the hock in the hindlimb?

Answer 63

Horse's use this hardened keratin to scratch their face.