Intro to hoof disorders, claw disruption lesions Flashcards
Which claw bears the most weight?
outer claws (so they grow faster and the most issues are seen in the outer claw)
How fast do hooves grow a month?
5-6 mm
approx. 6 cm per year
When is the hoof blood flow the best? standing, walking, or resting
resting
When is a heifer full grown?
3 years or later
what are the medial and lateral sides called?
medial is axial wall
lateral is abaxial wall
What’s under the sole horn? And under that?
What’s the site of laminitis?
under the sole horn you have sole corium and under that you have the pedal bone (and fat pad/digital cushion)
site of laminitis is the wall of corium
Structure of the bovine claw.
Name them.
(A) Sagittal overview of the digit.
* 1 - first phalanx; 1a - meta-carpophalangeal joint;
* 2 - second phalanx; 2a - proximal interphalangeal joint;
* 3 - third phalanx/pedal bone; 3a - distal interphalangeal joint;
- 4 - distal sesamoid bone; 4a - podo-trochlear bursa;
- 5 - superficial flexor tendon; 5a - section of the palmar/plantar ligament of the second interphalangeal joint;
- 6 - deep digital flexor tendon; 6a - deep digital flexor retinaculum/distal annular ligament of the digits inserting at
the flexor tubercle; 6b - origin of the distal cruciate ligament of the digits; - 7 - common digital flexor tendon sheath;
- 8 - suspensory ligament of the interosseus muscle.
- (B) Enlargement of the area of the proximal interphalangeal joint
- (C) Enlargement of the area of the distal sesamoid bone
define periople
The periople covers the coronary band at the top of the hoof structure where the hoof meets the coat.
The periople is where the hoof grows, and it gives the keratin time to harden before it reaches the surface of the ground.
The two claws of a cow’s foot made of hard protein called keratin. The protein of keratin can absorb water.
What does this mean for lameness?
This is important because if hooves are continually wet, the keratin becomes
softer, and more easily damaged. For this reason, wetness and moisture can contribute to lameness.
- Dairy cows living in high rainfall areas, or under intensive conditions such as calving pads and feedlots, can have continually wet and soft hooves.
- On the other hand, if hooves are continually dry, the keratin becomes very hard, brittle and can crack more easily.
Hoof wall grows from
the coronary band and is the hardest part of the claw as well as the weight bearing part.
The horn of the sole consists of
horn tubules that are softer than those of the wall.
The sole corium is responsible for forming new sole horn - which grows down from the pedal bone.
Layers from pedal to sole horn.
bone
digital cushion
corium
basement membrane-stratum basale
stratum spinosum
stratum granulosum
stratum lucidum
stratum corneum
What is the white line in a hoof?
- Where the horn of the wall meets
the horn of the sole, there is a non-pigmented junction of weaker
horn known as the white line. - The white line has the ability to flex
slightly, being softer than both the
wall and sole, and runs from the
heel to the toe and around the first
third of the axial wall where it
ceases to be a weight-bearing
surface. - is Easily disrupted by Trauma
Touches the ground first when the animal is walking.
The bulb aka the Back part of hoof continuous with coronary band, composed of soft rubbery horn.
The digital cushion is Directly below the flexor tendon, which aids in
pumping blood throughout the foot.
- Serves as a shock absorber to protect the sensitive tissues from the bones of the hoof.
Hoof angle should be how much?
- Front feet 45-50°
- Back feet 50-52°
Hoof Dorsal wall length should be approx.
~7,5 cm
- Individual Look at the white line
(is longer in Holsteins)
Which claw is bigger in the front?
Which claw is bigger in the back?
- Front claws – claws quite similar (medial slightly bigger)
- Hind claws – lateral claw bigger and wider, medial claw smaller
Non infectious problems of the claw (4)
Claw horn disruption lesions:
- Sole hemorrhage
- Sole ulcer
- White line disease (Double heel)
Infectious problems of the claw (4)
- Heel horn erosion
- Digital dermatitis (DD)
- Interdigital phlegmon
- Interdigital dermatitis (ID)
sole hemorrhage
sole ulcer
white line disease
Describe the dermal-vascular system of the hoof.
- Arterio-venous anastomoses (AVA’s) are
shunts between the arterioles bringing the
blood into the capillary bed and the venules draining the blood from the capillary bed. - AVA’s occur at the base of the lamellae and papillae and in the deeper layers of the connective tissue of the claw.
The initial local laminitis reaction that takes place in claw tissues are
alterations in the vascular endothelial lining (roughening) and in the microcirculation.
- These events are followed by the activation of a variety of interacting and cross linked inflammatory and regulatory cascades.
The pedal bone of the claw is suspended by
a collagen fiber system inside the claw capsule.
The pedal bone is kept in a certain position preventing
excessive pressure on the sensitive dermis and living horn producing epidermis.
All of the structures between the surface of the bone and the inner aspect of the cornified claw capsule contribute to
suspensory functionality; in their functional entity they are called the
suspensory apparatus of the pedal bone.
This apparatus consists of a dermal component with a deeper reticular layer and a superficial papillary layer (dermal
papillary body) and an epidermal component including living
epidermal layers and the inner parts of the stratum corneum.
For whatever reason, a loosening or increase in length of this connective tissue occurs it will lead to displacement (sinking,
rotation, tilting) of the pedal bone within the horn capsule and subsequent increase in pressure onto the soft tissue
between bone and horn.
The digital cushion extends forward
beneath the pedal bone and is
made up of
three cylindrical parallel oriented bodies each with a capsule of connective tissue filled with soft fat (semi-liquid).
- The dermis of the sole and heel
and the underlying fat cushions in
the subcutis function as ‘shock
absorbers’ bearing a considerable
proportion of the impact of the
first phase of each step the animal
makes when walking.
Changes in digital cushions seem to be correlated with
metabolic changes around parturition and associated changes in body condition.
How does pressure cause lameness?
Inapprorpiate forces on germinal epithelium of the sole lead to
Hemorrhage beneath distal phalanx, active claw horn lesions which lead to
Inflammation and lameness
Sinking of the pedal bone
