Carnivore & Ruminant Feet

How does the distal phalanx look in the carnivore?

• Distal phalanx: Carnivore:

• Ungual process - supports claw

• Ungual crest - vascular root of claw

• Extensor process - extensor tendons

• Palmar process - flexor tendons

Cats and dogs are ______.

digitigrade

Describe the digital pads, metacarpal/tarsal pad and carpal/stopper pad in the dog and cat paw.

• Digital pads (d) (n=4):

• overlies DIP joint

• Metacarpal / metatarsal pad (m) (n=1):

• heart shaped

• overlies MCP / MTP joints

• Carpal / stopper pad (c) (n=1):

• Forelimb only, none in the hindlimb

• Protects accessory carpal bone

What are the functions of the footpads in the carnivore?

• Allow weightbearing over entire digit

• Support digit & metacarpo / metatarso

• phalangeal joints

• Protect deep structures

• Anti-concussion / shock absorption

• Resistance to trauma / wear & tear

• Traction - prevent slipping

What muscle in the carnivore distal limb helps provide phalangeal joint support, similar to the suspensory ligament in the horse?

Metacarpo/metatarso - phalangeal joint support

• Interosseus muscle for each digit

• (cf suspensory ligament in horse)

• Support from metacarpal / metatarsal foot pad

Describe the surface of the skin found in carnivore footpads.

• Modified skin

• Dermis (d)

• Germinative layer (g) - active

• Epidermis (e)

  • Keratinised stratified squamous epithelium

• Thick for protection, to sustain wear and tear

• Maintained by increased turnover of cells

• Rough surface (thrown up in conical papillae) for traction

• Sweat glands in pads, but only this location in dogs (Which is why they rely on panting)

  • For heat loss

• Variable amounts pigmentation

What tissue provides the digital cushion in the carnivorous footpads?

Digital cushion, which contains:

• Fibrous tissue

• Elastic tissue

• Fat

• Vascular channels

• Function = Shock absorption

Why is the digital cushion of clinical significance?

• Vascular channels

• Messy, considerable amount of blood

• Elastic tissue

• Suturing, not a great idea, possibly use glue or bandage

• Sweat glands

• Keep in mind when bandaging, need to absorb fluid and be changed frequently

What structures compose and make the layers of the carnivore claw?

• Dermis

• Fused to periosteum of ungual process

• Sensitive and bleeds if damaged

• (No laminae like in the horse)

• Epidermis

• heavily keratinised = horn +/- pigment

What are the two active layers in the carnivore claw?

• Germinative layer

• active in 2 areas (same as horse)

1. Recess at ungual crest

• Forms dorsal & lateral surface of claw

2. Palmar surface ungual process

• Forms underside of claw

How does the normal claw look in the dog?

• Tip touches the ground, usually has continuous growth but wears naturally

• Balanced forces of Dorsal elastic ligaments / CDE / DDFT

What are the consequences of reduced wear to the claws of dogs?

• Claw grows in circular fashion

• Can eventually grow into pad

• Need trimmed!

• Cut epidermis & not dermis

• Pigmented & non-pigmented

How does the normal claw look in the cat?

• How are they exposed?

• What does de-clawing entail?

• Claws not normally visible:

• Very strong dorsal elastic ligament

• Neutral position = DIP joint hyperextension

• Distal phalanges rotated dorsally

• Claws rests in skin fold / sheath between phalanges

• Is a lifestyle so they remain sharp for hunting / climbing etc.

• Exposure of claws:

• DDFT flexes joint

• Manual pressure to digital pad

• De-clawing - amputation of distal phalanges

Describe the ruminant distal limb, beginning with the metacarapals.

• Metacarpals 3 & 4 / Metatarsals 3 & 4:

• Fused

• 2 x Metacarpo / metatarso - phalangeal joints —

• 2 x pairs proximal sesamoids

• Digits 3 & 4:

• All bones present

• Weight bearing

• 2 x proximal interphangeal joint

• 2 x distal interphalangeal joint

• 2 x distal sesamoid bones

• Digits 2 & 5:

• Dew claws / little hooves palmar aspect MCP / MTP joint

• Digit 1 absent

The ruminant has a _____ hoof. What does this mean?

• What are the main structures of the hoof?

cloven

• Medial and lateral claws

• Interdigital cleft - division down the center

• Sole (1)

• Heel (2)

• No frog

• Wall:

• Lateral - convex

• Continuous with heel

• Medial - vertical

• Stops at parapedal groove

• Transition hard to soft horn = region is prone to damage

• White line - space between hoof wall and the sole

What allows the ruminant feet to be good shock absorbers?

Shock absorption:

• Bulbous heels

• Digital cushion

• Digits splay:

• supported by interdigital ligaments

• No lateral cartilages

• No frog

How does hoof growth occur in the ruminant hoof?

• Hoof growth:

• Coronary band - contains germinative epithelium 

• Only distal part of dermis covered by laminae

• Sensitive laminae

• Insensitive laminae

• Primary laminae only

• No secondary

What are some clinical consideration of cow hooves?

• Welfare, Effect on production

• Horn overgrowth:

• Soft ground, overgrowth to do with weight distribution

  • FL = inner claw

  • HL= outer claw

• Solar ulcers:

• especially parapedal groove, since it is softer

• Abrasive flooring

• Interdigital dermatitis - infection between claws

• Secondary infection

• can track up DDFT sheath

How do sheep hooves appear?

• Same components as cattle

• Skin gland proximal to interdigital cleft

• Overgrowth also a problem

• May need pared