Foot shape and radiographs of free-ranging Nubian giraffe in Uganda

Abstract

Foot health in zoo giraffe has been a topic of recent research, although little is known about the foot health of free-ranging giraffe. This study describes the foot shape and radiographic pathological changes in 27 young adult Nubian giraffe (Giraffa camelopardalis camelopardalis) from a translocation in Uganda (August 2017). Giraffe feet were observed to have a concave sole, the hoof wall was longest by the toe tip, and the weight-bearing surface of the foot was primarily along the periphery of the foot including hoof wall, parts of the heel, and the edge of the sole. Radiographs showed that pedal osteitis and sesamoid bone cysts were relatively uncommon (3/24 giraffe with osteitis, 1/24 giraffe with sesamoid cysts), and that no giraffe in the study had P3 joint osteoarthritis, P3 rotation, or P3 fractures. Radiographs consistently demonstrated a positive palmar/plantar angle with the sole of the hoof thicker at the heel than by the toe tip, with the non weight-bearing palmar/plantar angle measuring 1.6°- 4.3°. This is the first systematic review of foot shape and radiographs in free-ranging giraffe and demonstrates a low prevalence of foot pathologies. This study suggests qualitative differences in foot shape, foot health, radiographic anatomy, and foot pathologies when comparing free-ranging and zoo giraffe. Further research is needed to identify why these differences occur and whether husbandry modifications could help improve zoo giraffe foot health and prevent associated lameness.

Fig 1. Giraffe positioning during immobilization.

A leg rope was used on the giraffe for human safety during foot health evaluations and radiographs. The person holding the x-ray generator wore a leaded gown and a thyroid shield while collecting radiographic images. All other personnel were at a distance of at least two meters from the x-ray generator.

Fig 2. Foot radiographs from free-ranging young adult giraffe.

Projections were collected with giraffe in lateral recumbency, using either a medial or lateral oblique projection (dorsomedial-palmarolateral or dorsolateral-palmaromedial oblique). (A) Normal front foot with no pedal osteitis or sesamoid cysts. (B) Abnormal front foot with mild (level 1) pedal osteitis on the dorsal surface (blue arrow) and sesamoid cysts (in circle). (C) Normal hind foot with no pedal osteitis or sesamoid cysts. (D) Abnormal hind foot with mild (level 1) pedal osteitis involving both the dorsal and plantar surfaces (blue arrow). In both the front and hind feet the sole plane runs parallel to P3 bone. Compared to the front foot, the hind foot has a more rounded toe tip of the distal phalangeal bone.

Fig 3. Giraffe foot sole height was thicker by the heel than by the toe tip, demonstrating a positive palmar angle.

(A) Using an oblique view, sole thickness was measured from the most caudal and most distal weight-bearing aspect of P3. (B) For feet where medio-lateral or latero-medial radiographs were also available, the average palmar angle was 2.65° (range 1.88°-4.29°) and the average plantar angle was 2.26° (range 1.61°-3.23°).

Fig 4. Lateral view of a giraffe front foot, showing a relatively straight coronary band.

Fig 5. Solar views of giraffe front feet, demonstrating how hooves are self-maintained during the rainy season in Murchison Falls National Park, Uganda.

(A) A well maintained balanced capsule and no hoof wall overgrowth. The wall at the toe tips and periphery (↑) is worn to the same level as the sole. (B) A foot with mild hoof wall overgrowth by the toe tip still maintains good foot symmetry medially to laterally, but has a slightly overgrown lateral toe tip (blue triangles). The medial claw hoof wall (↑) has broken or chipped off and is being worn off to the level of the sole. For the lateral claw, the hoof wall has grown beyond the level of the sole (blue triangles) and is starting to chip or break off. This suggests that many hooves are not getting much longer than moderate overgrowth before the process of exfoliation of the sole and breaking the hoof wall happens, which maintains the balance of the hoof capsule. (C) A foot with moderate overgrowth of the hoof wall, sole, and heel (↑). This foot has prominent sole papillae (□). (D) Close-up of sole papilla from 5C, which have a hair-like projections as the sole starts to overgrow.

Fig 6. The solar surface of the giraffe’s foot is concave with hoof ground contact points around the periphery of the foot including the hoof wall, heel, and parts of the sole.

Paint marks the most prominent aspects of the sole with the giraffe in lateral recumbency, with most paint on the hoof wall and heel.