Equine foot and passive stay apparatus:

• Manus = structures distal in the thoracic limb.
• Pes = structures of the distal pelvic limb.
• More weight is held in the forefoot than the hind.
• 3rd metatarsal is longer/rounder than the 3rd metacarpal in cross-section.
• Trauma to cartilage can cause ossification which can lead to sidebone and cause lamness.
• Penetrating injury to the coronary band can infect the ungual cartilage which leads to quittor - chronic drainage tracts.
• Corium = vascular, innervated tissues deep to the cornified hoof - like dermis of the skin.
• Periople = waxy hoof surface.
• Most of the horse's weight is transferred to by the laminae to the hoof wall rather than the sole.
• Laminitis = laminae inflammation, severity can cause detachment of insensitive from sensitive laminae - hoof wall and distal phalanx attachment is lost.
• Sole = keratinized plate attaching to the plantar surface of the 3rd phalanx.
• Tendonitis/tenosynovitis = strain of flexor tendons, inflammation causes a convex appearance - bowed tendons. Often seen in horses used at speed.
• The foot has lateral and medial collateral ligaments, the suspensory ligament runs parallel to the cannon bone and branches at the fetlock.
• Superficial and deep flexor tendons share a synovial sheath 5-8cm above the fetlock.
• Wind galls = excessive synovial fluid within the palmar recess.
• The frog aids vascular shunting and dissipates shock energy.
• Internal hoof structures = distal interphalangeal joint, podotrochtear bursa (navicular), distal end + insertion of the DDFT, insertion of the common DET and navicular ligaments.
• Integument cavity = hoof covering.
• Subcutaneous tissue/subcutis contains elastic/collagenous connective tissue, blood vessels and nerves. (Digital cushion and coronary cushion).
• Corium = very sensitive, bleeds heavily if injured and supplies nutrients to the epidermis. Papillae - finger-like projections and lamina - leaf-like structures increase SA.
• Germinal layer = keratinocytes which grow through divisions and is close to the dermis to receive nutrients.
• Corneal layer = dead cells, keratin proteins which reinforce the hoof wall.
• Corneocytes produce cementing substance ( intracellular cementing substance). Firm cohesion using the membrane coating material.
• Corneocytes are arranged in a 3D structure.
• Tubular horn = hollow space (medulla) which reinforces the stable structure of the hoof wall.
• Lamellar horn = forms over the dermal lamellae which is important for suspensory mechanisms.
• 5 hoof capsule segments = perioplic, coronary, lamellar, sole and frog/bulbar.
• Perioplic segment = thin band of horn around the hoof hairline which is rubbery when wet.
• Coronary segment = largest, most of the hoof wall, 10mm to the coronary band and subcutaneous layer is the coronary cushion.
• Lamellar segment = next to the coronary segment, 600 primary dermal lamellae, white line and junction between the hoof wall and sole.
• Sole segment = attached to the pedal bone and the outer layer flake off.
• Frog/bulbar segment = caudal hoof, short papillae, higher water content for elasticity and the digital cushion shock absorbs.
• Hoof bars = palmar limit and the buttress of the heel.
• Angle of the bars = corresponding edge.
• Sole = concave, only bearing edge and the frog touch the ground.
• Suspensory apparatus issues = blood sugars, health problems/overloading and hormonal imbalance.
• Coronary hoof = 7-8mm growth per month.
• Sole and frog horn = 4-5mm growth per month.
• Hoof wall takes 1 year to regrow (100mm).
• Sole and frog regrow every 3-4 months.