Anatomy of the Hoof Flashcards
What are the 9 functions of the hoof?
- Protection
- Support
- Weight distribution
- Traction
- Shock absorption
- Blood circulation
(Secondary)
- Tools
- Sensory organs
- Weapons
What is the weight distribution in the horse leg?
P2 -> P3 -> laminae -> hoof wall -> ground
What is the distal phalanx composed of?
- Hoof wall: inner & outer
- White line
- Frog
- Bones
- Nerves
- Venus plexus
What is the outer side of the hoof composed of?
- Hoof wall
- Coronary band
- Periople
- Inner wall
What is the underside of the hoof composed of?
5 structures
- bulbs of the heel
- bars
- sole
- frog
- white line
What is the inner side of the hoof composed of?
- Bones
- Cartilage
- Tendons
- Ligaments
What is the very tough vascular structure that sits at the top of the hoof wall?
the coronary band
What are the 2 major functions of the coronary band?
- 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
What is corium?
Any portion that has sensitive parts
(also called sensitive laminae, lamina, or dermis)
What are papillae?
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.
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.
Periople
What is laminitis of the hoof?
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.
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
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.
What are 9 common hoof problems?
(video links below)
https://www.smartpakequine.com/learn-health/common-horse-hoof-problems
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
How are hoof or quarter cracks formed?
Caused by changes in hydration, conformation, and balance. They are linear cracks in the hoof.
What is a hoof bruise?
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.
5) Hoof Abscess
White line disease
7) Navicular syndrome
Describe a hoof canker:
https://www.smartpakequine.com/learn-health/equine-canker
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.
9) Club foot
Why is the horn material soft in the early stages?
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
What are the 3 layers of the hoof wall?
- External layer (stratum externum)
- Middle layer (stratum medium)
- Internal layer (stratum internum)
What are the parts of the hoof wall?
- dorsal part/toe (pars dorsalis)
- sides/quarters (pars lateralis et medialis)
- heels (pars mibilis lateralis et medialis)
- bars (pars inflexa lateralis et medialis)
The outer wall is pigmented and contains a higher ratio of _____.
tubules
How does a healthy hoof wall look?
- slightly thicker at the toe
- no growth rings or cracks
The hoof outer wall also regulates the output or input of ________.
moisture
What color is the inner wall of the hoof?
white
What is the function of the inner wall?
To help the hoof wall stretch and the moisture protects inner structures from shock.
What causes hoof rings?
1) laminitis
2) nutritional changes
3) stress
4) trauma
What is the hard surface of the hoof, similar to the human fingernail?
the horn
What produces the cells that form the horn?
corium - it contains many blood vessels and nerves
What is the white line (zona alba) of the hoof?
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.
What is the function of the white line of the hoof?
It is to seal off the border of the pedal bone to
protect it from bacterial infiltration; it aids in traction
What is the landmark that is between the sensitive and insensitive parts of the hoof?
the white line
In white line disease, the hoof is quite ___________?
powdery
What is the area inside the white line called (not including the bars and frog)?
sole
What is the function of the sole?
1) protect the sensitive structures beneath the sole
2) the outer perimeter provides support and shares from of the weight
Which sides of the hoof are sensitive and insensitive?
1) leg side (sensitive)
2) hoof side (insensitive)
What happens during coffin bone rotation (founder)?
the coffin bone is displaced and pierces the sole, which damages it
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?
frog
Why is the frog soft and pliable, elastic?
It is made of approximately 50% water
What are the parts of the frog called?
1) Point (apex)
2) Grooves along the sides (sulci)
3) Depression along the bottom surface (central sulcus or cleft)
What is the function of the frog of the hoof?
1) expand and contract the heels of the foot as it moves
2) protects the digital cushion
3) traction for shock absorption
What disease or infection affects the frog?
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.
How often frog shed?
twice a year
What happens if the frog doesn’t do its job and the heels become contracted?
occur when the heels of the hoof shrink or move closer together, narrowing the heel area and potentially causing discomfort or lameness
What is often called the “heart of the hoof”?
the frog, because its contraction and relaxation enables venous return of the blood
How is the hoof supplied by blood?
There are 5 venous plexuses: (names correspond to what they do)
1) solar
2) digital cushion
3) lateral cartilage
4) lamellae
5) coronary
Why would nerve blocking of the hoof be helpful?
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.
What are the 4 types of nerve blocks of the hoof?
https://www.midriversequine.com/nerve-blocking-horse-lameness-exam/
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.
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?
the bar
What is the function of the bar?
1) control the movement of the back of the hoof
2) adding strength to the heel area
3) protecting it from excess distortion.
Where is the collateral groove?
the groove that runs along either side of the frog between the bar and the sole.
Where does the tendon of the deep digital flexor muscle attach?
semilunar crest of P3 (coffin bone)
What is side bone of the hoof?
Hardening or ossification of the lateral cartilages on either side of the coffin bone
Which bone of the hoof sits partially inside the hoof and just above the coronary band?
P2 (short pastern bone)
Where is the navicular bursa and what is its function?
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
What bones do the T-lig and impar ligament attach to?
T-lig: DDFT, P2, navicular
Impar: Navicular and coffin
What is the digital cushion made of? Where is it located?
fibrocartilage and fat ; It is located between the frog and the heel bulbs
What is the podotrochlear apparatus (PTA) consist of?
Navicular bone, T-ligaments, impar ligament, & DDFT
What is deciduous horn shoe (eponychium)?
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”.
What is the ergot / night eye above the knee in the forelimb on the inner side and below the hock in the hindlimb?
Horse’s use this hardened keratin to scratch their face.
