Fig 1.
Giraffe hoof capsule and corium.
(A) Reflection of the hoof wall reveals both insensitive and sensitive tissues, including the interface between the hoof capsule and corium. (B) After removal of the hoof wall, the parietal surface of the distal phalanx (Pd) corium displays its normal proximal-to-distal organization. The more proximal region (outlined, left) corresponds to the coronary cushion and contains short papillae. Distally, these papillae transition into long, parallel primary laminae (outlined, right), forming the laminar corium. A gradual transition zone occurs naturally between these regions. (C) Higher magnification of the coronary band shows fine, elongated papillae (←), while the adjacent laminar region displays broad, elongated laminae (Δ). (D) At the toe tip and lateral margins of the digit, the corium consists of long, broad papillae (Δ), consistent with load-bearing areas.
Fig 2.
Sagittal sections of giraffe right front foot medial digits showing normal and abnormal sole alignment.
Sagittal (parasagittal) sections are shown from four male giraffe (A-D) and two female giraffe (E, F). In most feet (A-E), the solar surface of the hoof capsule is approximately parallel to the distal margin of distal phalanx (Pd). In contrast, foot F shows localized caudal sole overgrowth (Δ). The dotted line indicates the expected plane of the solar surface in parallel with Pd; all capsule growth distal to this line represents overgrowth, with a distinct bulge visible distally in the sole. This panel is oriented obliquely to emphasize both the normal concavity of the sole and the abnormal caudal overgrowth. Feet A and B had been thawed before dissection, then re-frozen, and showed generalized hemorrhage on sectioning.
Fig 3.
Histology sampling sites in the medial digit of a giraffe’s front foot.
Corium samples were collected from: (A) coronary cushion, (B) laminae, (C) toe tip, and (D) caudal sole. Additional samples included: (E) solar surface of the distal phalanx (Pd), (F) digital cushion, (G) distal sesamoid bone, and (H) deep digital flexor tendon.
Fig 4.
Solar surfaces of the hoof capsule and underlying corium in a giraffe.
(A) The solar surface of the hoof capsule shows a relatively long peripheral wall and a centrally concave sole, with the heel and hoof wall serving as initial points of ground contact. The interdigital (➤) and caudal (Δ) hoof wall terminations define the borders of the caudal sole. (B) The exposed corium on the palmar/plantar surface of the foot also exhibits a central concavity. The papillae at the toe tip (←) and wall margins are longer, thicker, and darker red compared with the central sole, which contains shorter papillae (☆). (C) Close-up view of the paler corium of the central sole region corresponding to the ⋆ area in panel B, where the corium remains attached to the solar surface of the distal phalanx (Pd). In this region papillary height is reduced compared with the darker, more robust papillae at the toe tip and wall margins. The view is oriented from distal to proximal, analogous to panel A but with the epidermal sole removed.
Fig 5.
Corium histology in the giraffe front foot.
The corium interdigitates with the hoof capsule through both papillary and laminar connections. (A) Coronary cushion: the corium forms papillae (H&E stain, 9.4x). (B) Dorsal hoof wall: laminar connections are present without secondary laminae or evidence of laminitis (H&E stain, 10.3x). (C) Toe tip: elongated papillae are present (H&E stain, 6x). (D) Caudal sole: elongated papillae are also present (H&E stain, 2.5x).
Fig 6.
Sagittal section of the giraffe hoof capsule sole with regional close-ups.
(A) Longitudinal section of the sole from heel to toe (toe tip oriented to the right). The sole is thickest beneath the toe tip and heel, and thinner across the central and caudal sole regions. Tubules within the sole are arranged diagonally, angling dorso-distally toward the tip of the hoof. (B) Heel region: ruler demonstrates sole thickness and diagonal tubule orientation. (C) Central sole region: thinner sole with consistent diagonal tubule orientation. (D) Toe tip region: ruler indicates greatest thickness and oblique tubule orientation.
Fig 7.
Cross-sectional anatomy and histology of the giraffe digital cushion.
(A) Gross transverse section of the distal limb showing two distinct regions of the digital cushion: a proximal soft region (☆) composed of adipose tissue and a distal firm region (Δ) composed of dense connective tissue. The proximal region lies palmar to the deep digital flexor tendon (→) and extends distally beyond its terminal attachment, adjacent to the distal sesamoid bone of the digit. (B) Histological section (H&E stain, 4.9X) of the same regions confirms this distinction, with the proximal portion (☆) consisting of adipose tissue and the distal portion (Δ) composed of dense fibrous connective tissue.
Fig 8.
Histology of giraffe distal limb structures.
Histological sections show: (A) Distal phalanx (Pd) near the caudal sole (H&E, 6.2x); (B) Pd (H&E, 6.3x); and (C) deep digital flexor tendon (DDFT (H&E, 8.7x). No significant pathologic changes were identified in these tissues.