2 Anatomy: Equine Hoof, Foot

Front 1

foot:

Back 1

foot:
1. epidermis: hoof, highly keratinized, no vessels or nn
2. dermis: soft, sensitive
3. SQ tissue: digital and coronary cushions
4. ligaments and bones of coffin jt
5. blood vessels, nerves
6. flexor and extensor tendons
7. same for all limbs: only change plantar/ palmar, common digital extensor to long digital extensor

Front 2

foot bruising

Back 2

clinical problems:
foot bruised often as:
1. may remain in wet, putrid conditions for long periods
2. steps on hard, stony or uneven terrain

Front 3

pyramidal dz

Back 3

pyramidal dz:
- ringbone condition of extensor (pyramidal) process of distal phalanx

Front 4

hoof wall

Back 4

hoof wall :
- visible part when on ground
- coronet: jxn b/w hoof and skin
- basal border: on ground
1. toe
2. quarters
3. heel

Front 5

heel

Back 5

heel:
- wall reflects to form bars, separated from frog by paracuneal grooves

Front 6

toe

Back 6

toe:
- thickest part of wall, thins progressively heel-ward

Front 7

quarters

Back 7

quarters:
- lateral has a thicker wall

Front 8

hoof angles

Back 8

hoof angles:
between dorsal surface and ground
1. FL: 45-50 degrees
2. HL: 50-55 degrees

Front 9

wall substance

Back 9

wall substance:
- tubules extending proximo-distally
- held together by amorphous, glue-like intertubular horny material

Front 10

layers of wall

Back 10

layers of wall:
1. stratum externum: periople and stratum tectorium
2. stratum medium
3. stratum internum

Front 11

stratum externum

Back 11

stratum externum:
- layer of wall
- very thin, tubular horny covering
1. periocle
2. stratum tectorium

Front 12

periople

Back 12

periople:
- proximal part of stratum externum (hoof wall)
- soft, non-pigmented
- expands caudally over bulbs of heels

Front 13

stratum tectorium

Back 13

stratum tectorium:
- part of stratum externum (hoof wall)
- covers rest of wall
- impervious to water, smooth, glossy
- direction of growth of horny tubules: parallel, proximo-distal lines
- variations in hoof growth: horizontal smooth ridges

Front 14

stratum medium

Back 14

stratum medium:
- very thick, bulk of hoof wall
- tubules and intertubular horn
- may be pigmented outer layers: no known effect

Front 15

stratum internum

Back 15

stratum internum:
- innermost hoof wall
- NEVER pigmented
- coronary groove proximally
- bears openings accomodating papillae of underlying dermis
- inner surface: keratinized primary laminae, non- keratinized secondary laminae
- caudally: form laminae of bar

Front 16

sandcrack, grascrack

Back 16

1. sandcrack: crack in wall of hoof extending proximodistally
- will continue until worn down
2. grasscrack: less serious, split in wall extending proximally from basal border

Front 17

sole

Back 17

sole:
- concave (normally), flaky outer surface
- angles: b/w walls and bars
- vertical horn tubules and intertubular horn

Front 18

frog

Back 18

frog:
- wedge-shaped
- incompletely keratinized: 50% water vs sole 35% water so softer
- sulcus: separates med, lat crura
- apex: crura meeting cranially
- expands palmarly to join med/ lat bulbs of heels

Front 19

thrush

Back 19

thrush:
- degenerative condition of frog
- esp moist or watery floor/ ground

Front 20

navicular dz, quittor

Back 20

1. navicular dz
2. quittor: suppurative, degeneration of cartilage

Front 21

sidebone

Back 21

sidebone:
- ossified, rigid cartilages of distal phalanx (attached to palmar process of phalanx)
- normally: hyaline in young, fibrocartilage in adults

Front 22

internal surfaces of frog

Back 22

internal surfaces of frog:
1. spine (frog stay): embedded in digital cushion
- bordered by grooves which are surrounded by ridge of frog
2. holes for papillae of frog and sole dermis

Front 23

dermis

Back 23

dermis:
- highly vascular, sensitive
- attaches hoof wall to internal foot structures
- produces various parts of wall by means of surface papillae (except laminar dermis)

Front 24

dermis nourishment

Back 24

dermis providing nutrients:
1. periploic
2. coronary
3. laminar
4. sole
5. frog

Front 25

periploic dermis

Back 25

periploic dermis:
- narrow, pale
- coronet below periople
- broadens, joins bulbs of heels
- blends with frog dermis
- papillae produces:
1. horn of periople -and-
2. stratum tectorium (externum)

Front 26

coronary dermis

Back 26

coronary dermis:
- thick, pigmented in dark hoofs
- coronary groove, distal to periploic dermis
- covers extensor t, cartilages of distal phalanx via SQ tissue of coronary cushion
- numerous surface papillae (~5 mm): fit into holes in strata medium and internum of coronary groove

Front 27

production by coronary dermis

Back 27

production by coronary dermis:
- most of wall
1. stratum germinativum produces stratum medium
2. cells of papillae produce tubular horn
3. interpapillar cells produce intertubular horn (glue)

Front 28

coronary venous plexus

Back 28

coronary venous plexus:
- deep in coronary cushion
- anastamoses with palmar/ plantar venous plexuses through foramina in cartilages
- will bleed profusely

Front 29

laminar dermis

Back 29

laminar dermis:
~ 600 primary laminae with several non-keratinized sec laminae
- colorless, interdigitate with laminae of wall and bars
- deep part blends with periosteum of distal phalanx: P from 2nd phalanx directed away from sole to wall
- terminal papillae: distal parts of dermal papillae, produces part of white line
- distal fringe of coronary papillae: produces wall laminae
- dorsal venous plexus deep

Front 30

laminitis

Back 30

laminitis:
- extremely painful
- separation b/w sensitive and insensitive laminae
- new non-tubular horn produced due to stimulation of stratum geminativum
- 3rd phalanx rotated downward, pushing sole down (dropped sole)
- seedy toe: laminar dermis of toe separated from wall by space filled with amorphous, crumbly material produced by dermis

Front 31

sole and frog dermis

Back 31

sole and frog dermis:
- usually pigmented
- numerous papillae fit into hole in sole and frog
- stratum germinativum produces horn of sole and frog
1. sole dermis: attached to undersurface of 3rd phalanx
2. frog dermis:
- attached to digital cushion above

Front 32

white line

Back 32

white line:
- junction of wall and sole
- thin, soft, pale horn:
1. pigmented: produced by stratum germinativum overlying terminal papillae ( on distal parts of laminar dermis)
- fill space between non-pigmented
2. non-pigmented: deep layer of stratum medium and distal parts of horny laminae
2.

Front 33

palmar/ plantar venous plexus

Back 33

palmar/ plantar venous plexus:
- deep in sole dermis and on surfaces of cartilages of the 3rd phalanx

Front 34

dermis problems

Back 34

dermis problems:
1. corn: general dermis injury
2. bruised sole: dermis at angle of sole
3. canker: chronic hypertrophy of frog dermis, usually due to infection

Front 35

digital cushion

Back 35

digital cushion:
- between cartilages of distal phalanx, overlying frog
- distal to 2nd phalanx and DDF tendon (overlies)
- caudally forms bulbs of heels
- fibroelastic tissue, may have scattered areas of cartilage
- pale yellow, fatty, some modified skin glands
- denser towards toe than at hells where it supports the bulbs
- thicker at heel, more spongy: concussion abs

Front 36

coronary cushion

Back 36

coronary cushion:
- elastic SQ tissue of coronary dermis
- attaches coronary dermis to DDF tendon and cartilages of distal phalanx
- blends with digital cushion at prox aspect of heel