The Hoof

Equine thoracic limb Stashak

Equine foot Banks

Banks

Hoof - Epidermis Wall Wall Bars Bars Sole Sole Frog Frog Stashak Fig. 1.4

Hoof Epidermis (orange) Dermis (green)

Hoof - Epidermis Bacha & Bacha Fig Stashak Fig. 1.4

Hoof - Epidermis Hoof wall Hoof wall Bars Bars Sole Sole Frog Frog

Equine hoof wall

Hoof wall Perioplic epidermis = stratum externum, stratum tectorium Perioplic epidermis = stratum externum, stratum tectorium Coronary epidermis = stratum medium, tubular epidermis Coronary epidermis = stratum medium, tubular epidermis Tubular and intertubular horn Tubular and intertubular horn Laminar epidermis = stratum lamellatum Laminar epidermis = stratum lamellatum Non-tubular horn Non-tubular horn Fuses to stratum medium and connects wall to dermis Fuses to stratum medium and connects wall to dermis

Hoof Figure 34. Junction of epidermis and hoof, 6X. The figure shows the area of the periople; this is the region of the epidermis that gives rise to the stratum externum. Distal to the periople is the coronary region; this is the region where the stratum germinativum of the epidermis gives rise to the tubular and intertubular horns of the stratum medium. The coronary region is seen at higher magnifications in the figure that follows. epidermis periople stratumexternum coronary corium epidermis at coronary region coronary region

Hoof wall Perioplic epidermis, stratum externum Perioplic epidermis, stratum externum Coronary epidermis, stratum medium Coronary epidermis, stratum medium Laminar epidermis, stratum lamellatum Laminar epidermis, stratum lamellatum Stashak Fig. 1.5

Coronary epidermis, stratum medium Tubular horn Tubular horn Intertubular horn Intertubular horn

Figure 28. Cross section of the wall of equine hoof, 6X. Section was taken from a young horse. The hoof is the horny epidermal covering of the distal end of the digit; it is composed of dead keratinized cells. The wall of the hoof, on cross section, shows a stratum externum (external layer), a stratum medium (middle layer), and a stratum internum (internal layer). An area similar to that in the inset is seen at higher magnifications in the figures that follow. Hoof stratum externum stratum medium stratum internum dermis (corium)

Figure 29. Equine hoof, cross section. 20X. The figure shows the stratum externum and stratum medium. The stratum externum (stratum tectorium) is a thin layer of flat keratinized cells. The stratum medium comprises the bulk of the wall and is composed of tubular horn and intertubular horn. The inset is seen at higher magnifications in the next figures. Hoof stratum externum stratum medium tubular horn intertubular horn

Figure 30 A-B. Stratum medium of hoof wall. A-50X, B-200X. The stratum medium is composed of tubular and intertubular horns. The inset in Figure A shows a tubular horn which is magnified in Figure B. The tubular horn is composed of spirally arranged cells that do not cornify (keratinize) as completely as those of the intertubular horn and they stain more intensely (basophilic). The intertubular horn is composed of flat keratinized layers of cells. Hoof tubular horn intertubular horn A B

Stratum medium – tubular and intertubular horn

Stratum lamellatum Primary laminae Primary laminae Secondary lamina Secondary lamina

Equine hoof wall

Primary and secondary epidermal laminae

Figure 28. Cross section of the wall of equine hoof, 6X. Section was taken from a young horse. The hoof is the horny epidermal covering of the distal end of the digit; it is composed of dead keratinized cells. The wall of the hoof, on cross section, shows a stratum externum (external layer), a stratum medium (middle layer), and a stratum internum (internal layer). An area similar to that in the inset is seen at higher magnifications in the figures that follow. Hoof stratum externum stratum medium stratum internum dermis (corium)

Figure 31. Stratum internum of hoof wall. 20X. The stratum internum (stratum lamellatum) is composed of several primary laminae, each of which bears several secondary laminae. The vascular connective tissue between the laminae is the laminar corium (dermis). Hoof primary laminae laminar corium secondary laminae

Figure 32 A-B. Stratum internum of hoof wall. A-50X, B-200X. Figure A shows primary laminae with several secondary laminae. The laminae are seen at high magnification in Figure B. The primary lamina is composed of dead keratinized cells. The secondary laminae are composed of living cells of the stratum germinativum of the epidermis. Hoof A B primary laminae laminar corium secondarylaminae bloodvessel bloodvessel primarylamina secondary laminae laminae

Bacha & Bacha

Primary and secondary laminae, equine hoof

Epidermis Bars, sole, frog Bars, sole, frog Epidermis is similar to tubular regions of wall Epidermis is similar to tubular regions of wall Horn material is softer than wall Horn material is softer than wall

Figure 37. Sagittal section of equine foot. 2X. This is the same section in Figure 33 and is being shown for orientation purpose. The figures that follow will show the region of the hoof sole (inset). Hoof P1 P2 P3 ds DDF DC sole of hoof wall of hoof epidermis dermis epidermis dermis coronary corium corium (Stratum germinativum of epidermis is located here) epidermis is located here)

Figure 38A-B. Region of the sole of hoof. A-6X, B-20X. The structure of the sole is similar to that seen in the coronary region. Notice the dermal papilla extending downward into the epidermis of the sole. The epidermal cells will produce tubular and intertubular horns similar to those seen in the stratum medium of the hoof wall. Hoof sole of hoof osseous tissue of P3 of P3 dermal papillae sole epidermis sole corium A B

Hoof Dermis (green)

Dermis (corium) Perioplic corium Perioplic corium Papillae are perpendicular to ground Papillae are perpendicular to ground Nourishes stratum externum Nourishes stratum externum Coronary corium Coronary corium Papillae are perpendicular to ground Papillae are perpendicular to ground Nourishes stratum medium Nourishes stratum medium Laminar corium Laminar corium Primary and secondary laminae instead of papillae Primary and secondary laminae instead of papillae Laminae are perpendicular to ground Laminae are perpendicular to ground Nourishes stratum lamellatum Nourishes stratum lamellatum

Papillae of the coronary corium

Corium of the Foot Corium Corium Continuation of the skin Continuation of the skin Contains elastic fibers and extensive venous plexus Contains elastic fibers and extensive venous plexus Intimately associated with periosteum of bones in foot Intimately associated with periosteum of bones in foot Frog corium contains modified merocrine sweat glands Frog corium contains modified merocrine sweat glands Digital cushion Digital cushion Fibroelastic connective tissue Fibroelastic connective tissue Acts as a shock absorber Acts as a shock absorber

Laminae Sensitive lamina Sensitive lamina Secondary epidermal lamina with nerve endings and germinal epithelium Secondary epidermal lamina with nerve endings and germinal epithelium Primary and secondary laminar corium Primary and secondary laminar corium Insensitive lamina Insensitive lamina Primary epidermal lamina – cornified material Primary epidermal lamina – cornified material

Desmosomes

Stratum lamellatum, sheep hoof

Nails, Claws and Hooves

Dog Claw Banks

Dellman Fig

Dog Claw Aughey & Frye

Dog Claw Aughey & Frye