Equine Stay Apparatus & Canine & Ruminant Feet

Question 1

what is the mechanism for passive weight bearing in horses

Answer 1

the stay apparatus

Question 2

what are the requirements for passive weight bearing

Answer 2

maintenance of all joints in weight bearing extension

Question 3

what do the proximal limb joints prevent

Answer 3

prevent flexion

Question 4

what does the carpus prevent

Answer 4

flexion

and hyperextension

Question 5

what does the distal limb joint prevent

Answer 5

prevention of hyperextension

Question 6

what is the serratus ventralis

Answer 6

suspends weight of body between forelimbs

Question 7

which muscles in the shoulder, elbow and carpus prevent flexion

Answer 7

shoulder: biceps brachi
elbow: collateral ligaments (caudal location), alignment of bones
carpus: lacertus fibrosis

Question 8

what components of the stay apparatus are at the carpus

Answer 8

1. palmar fibrocartilage joint reinforcement
2. SDFT and check ligament
3. retinaculum

Question 9

what components of the stay apparatus are at the MCP, PIP, DIP joints

Answer 9

DDFT and SDFT

check ligaments

annular ligaments

Question 10

what are the components of the MCP/fetlock joint in the stay apparatus

Answer 10

1. suspensory ligament
2. common digital extensor
3. proximal sesamoids
4. distal sesamoidean ligaments (short, cruciate, oblique, straight)

Question 11

what do the digital pads cover

Answer 11

the DIP joint

Question 12

where is the MCP/MTP pad

Answer 12

overlies the MCP/MTP joints

Question 13

what does the carpal/stopper pad cover

Answer 13

forelimb only

protects accessory carpal bone

Question 14

what are the functions of the footpads (6)

Answer 14

1. allow weightbearing over entire digit
2. support digit and metacarpo/metatarso (phalangeal joints)
3. protect deep structures
4. anti-concussion/shock absorption
5. resistance to trauma/wear & tear
6. traction - prevent slipping

Question 15

how is the metacarpo/metatarso - phalangeal joint supported

Answer 15

interosseus muscle for each digit (CF suspensory ligament in horse)

support from metacarapal/metatarsal foot pad

Question 16

what muscle is this

Answer 16

serratus ventralis

Question 17

what are the layers of the carnivore footpad

Answer 17

dermis (d)

germative layer (g)

epidermis (e)

Question 18

what are the features of the epidermis layer of the carnivore footpad

Answer 18

keratinized stratified squamous epithelium

thick for protection

Question 19

how is the footpad maintained

Answer 19

increased turnover of cells

Question 20

what are the contents of the carnivore footpad (5)

Answer 20

1. digital cushion
2. fibrous tissue
3. elastic tissue
4. fat
5. vascular channels

Question 21

what are the components of the carnivore claw

Answer 21

1. dermis
2. germinative layer
3. epidermis

Question 22

what are the features of the dermis in the claw

Answer 22

fused to periosteum of ungual process

sensitive and bleeds

Question 23

where is the germinative layer in the claw active

Answer 23

in 2 areas (same as horse)

1. recess at ungual crest (forms dorsal and lateral surface of claw)
2. palmar surface ungual process (forms underside of claw)

Question 24

what are the features of the epidermis of the claw

Answer 24

heavily keratinized = horn +/- pigment

Question 25

how does the carnivore claw balance forces

Answer 25

through dorsal elastic ligaments/CDE/DDFT tip touches ground continuous growth - wears naturally

Question 26

why are cat claws normally not visible

Answer 26

very strong dorsal elastic ligament

Question 27

what position is the DIP in neutral position in the cat claw

Answer 27

DIP joint hyperextension distal phalanges rotated dorsally claws rests in skin fold/sheath between phalanges

Question 28

how are cat claws exposed

Answer 28

DDFT flexes joint manual pressure to digital pad

Question 29

what are the features of the distal limb in the ruminant

Answer 29

the metacarpals 3 & 4/metatarsals 3 & 4 are fused 2x metacarpo/metatarso - phalangeal joints 2x pairs of proximal sesamoids

Question 30

what bones are present in the ruminant digits 3 & 4

Answer 30

all bones are present all are weight bearing 2x proximal interphalangeal joint 2x distal interphalangeal joint 2x distal sesamoid bones

Question 31

what is present in digits 2 & 5 in the ruminant

Answer 31

dew claws/little hooves palmar aspect MCP/MTP joint

Question 32

what digit is absent in the ruminant

Answer 32

digit 1

Question 33

what are the components of the ruminant hoof

Answer 33

1. cloven hoof (medial and lateral claws) 2. interdigital cleft 3. sole 4. heel (no frog) 5. wall (lateral = convex continuous with heel and medial = vertical stops at parapedal groove) 6. white line

Question 34

how does shock absorption occur in ruminant hoof

Answer 34

bulbous heels digital cushions digits splay (supported by interdigital ligaments) no lateral cartilages no frog

Question 35

where does the hoof growth occur in the ruminant hoof

Answer 35

coronary band --\> only part of dermis covered by laminae sensitive laminae insensitive laminae primary only not secondary

Question 36

what are the clinical considerations of the ruminant hoof

Answer 36

1. solar ulcers (esp. parapedal groove) 2. interdigital dermatitis 3. secondary infection (can track up DDFT sheath)