Comparative anatomy of the giraffe distal limb

Abstract

Giraffe in human care are known to experience significant clinical issues related to their feet. To characterize normal foot anatomy, we analyzed six sets of front and hind feet from wild Angolan giraffe and one calf in human care. We used computed tomography, three-dimensional reconstruction, sagittal sections, and gross dissection to acquire as much gross anatomical detail as possible. Significant anatomical findings include the deep digital flexor tendon that is very gracile as it crosses the fetlock and proximal phalanges but widens significantly before inserting onto the entire palmar/plantar surface of the distal phalanx. Significant subcutaneous abaxial veins were noted at the level of the fetlock in both front and hind feet. The digital cushion was found to be a complex structure consisting of two distinct regions, one underneath the distal phalanx, characterized by multiple transversely oriented small adipose compartments separated by dense connective tissue septa, and a significantly larger portion within the heel bulb, consisting of two sagittally oriented fat bodies encased in a dense connective tissue capsule and divided by a thick septum. The proportion of adipose tissue volume in the heel bulbs compared to the distal phalanx decreases with age. The thickness of the sole was found to be much greater than that of the wall and the sole appears to be the major weight supporting structure of the foot. In particular, the heel is greatly expanded in giraffe relative to other ruminants and was found to consist of softer material than the rest of the sole. Data presented here provide an overview of normal giraffe foot anatomy, which can be compared with data from giraffe in human care to better understand, guide treatment and prevention of abnormal anatomical conditions.