2. Footpads, hooves, horns, antlers Flashcards
What does the number of digital pads correspond to?
number of digits
The digital footpads are homologous with what?
- BULB of ruminates + pigs
-FROG of horses
what is the structure of footpads?
- Thick subcutis with adipose tissue, portioned by collagen + elastic fibres
- ligaments anchor pad to the skeleton
- thickly cornified epidermis
- have eccrine sweat glands
- has stratum lucid layer
what is the functions of footpads?
- protection
- grip
- shock absorber
what are the similar components of nails/claws/ hooves and there functions
similar components:
- wall
- sole
- footpad
functions:
- protects distal digit
- tool for scratching/digging etc
- defence/hunting
- blood circulation
what is known as the horn in nails/claws/hooves?
highly keratinised epidermis
where is the coronet found in horses?
junction between skin epidermis + hoof
what does periods of disturbed growth result in?
transverse ridges
nails/hooves/ claws are epidermal structure, how are they anchored to the underlying dermis?
interdigitations of laminae
in claws what is dermis also known as?
the ‘quick’
what is the dermis (quick) closely adhered to?
periosteum of distal phalanx
what keeps cats claws retracted?
elastic dorsal ligaments
what are the special considerations of horse hooves we should know?
- Digit loss - only digit III is weight-bearing
- Elongation of distal limb segments
- Muscle mass concentrated proximally
- Motion restricted to protraction and retraction
- All ‘cursorial’ adaptations for running
- no foot no horse
- poor venous return
what is the dermis called in the hoof?
corium
what are the 5 parts of the dermis in the hoof?
- perioplic
- coronary
- lamellar
- solar
- frog
what is the subcutis of a horse?
coronary cushion + digital cushion
what is the 3 layers of the hoof epidermis?
- stratum externum
- stratum medium
- stratum internum
in the 3 epidermis hoof layers, which are pigmented and which are not?
pigments = stratum medium
unpigmented = stratum externum and internum
what is the white line of a hoof?
junction of the soft sole of the foot and hard hoof wall
what is the white line made of?
the worn end of the epidermal laminae + the interlamellar horn from terminal papillae
what does the white line indicate the silhouette of?
distal phalanx/pedal bone
How does venous return in a horse hoof work?
- compression of the frog (footpad) pushes the digital cushion outwards and squashed the hoof cartilage
- venous plexus in the cartilages are squashed, squeezing the blood out into digital veins
- digital veins have valves so blood can’t flow backwards
what family are antlers seen in?
cervids
what are the similarities of horns and antlers?
- Initially formed from a bony core covered by integument
- Located on the frontal bone
- Paired and usually symmetrical
- Present or larger in males
- But in some species and breeds, both sexes can have horns e.g. cattle, reindeer, goats, some sheep
- Weapons, social signal
how do antlers grow?
- Antlers grow from an attachment on the skull (‘pedicle’)
- When growing, antlers are covered in well-vascularised skin (“in velvet”)
- When finished growing, blood supply to skin cuts off and velvet is shed (“in tatters”)
how do horns grow?
Horn bud starts out in the subcutis and later fuses to skull
are antlers branched?
yes
do antlers shed?
yes
why is it better do disbud a calf?
- Horn bud starts out ‘floating’ in integument
- Later attaches to frontal bone
- At 6 months, frontal sinus starts extending into horn’s bony core
what is the risk of a horn fracture or dehorning older animals?
sinus infection
