Bipartite Distal Phalanx and Navicular Bone in an Andalusian Stallion

Abstract

We describe the clinical findings and radiographic abnormalities of a horse with a bipartite distal phalanx and a bipartite navicular bone of the right forelimb. Associated findings including suspected keratoma and degenerative joint disease of the distal interphalangeal joint are described and possible etiologies are discussed.

Magnetic resonance and radiographic imaging of a case of bilateral bipartite navicular bones in a horse

“…Navicular bone partition is a rare, likely congenital, condition that has been described in horses . Multiple variations of the condition have been reported, including bi‐ and tripartition of the bone, unilateral and bilateral disease, as well as a case in which the distal phalanx was also divided .…”

“…This may be the result of a disturbance to the bone’s blood supply (such as vascular microtrauma or intra‐articular blood vessel compression) at the stage of gestation when angiogenesis occurs in the precursor cartilage model, thus leading to defective endochondral ossification and ultimately partitioning of the bone . Other authors have suggested the syndrome may be a form of mild polydactyly, as evidenced by a case of a bipartite distal phalanx and navicular bone in an Andalusian stallion . It is therefore possible that not all congenital partitioned navicular bones arise by the same pathophysiological process.…”

“…N avicular bone partition is a rare, likely congenital, condition that has been described in horses. [1][2][3] Multiple variations of the condition have been reported, including bi-and tripartition of the bone, unilateral and bilateral disease, 1,3 as well as a case in which the distal phalanx was also divided. 2 Navicular bone partition is generally not detected until well into a horse's working career (reported cases have ranged from 4 to 10 years of age at detection).…”

“…[1][2][3] Multiple variations of the condition have been reported, including bi-and tripartition of the bone, unilateral and bilateral disease, 1,3 as well as a case in which the distal phalanx was also divided. 2 Navicular bone partition is generally not detected until well into a horse's working career (reported cases have ranged from 4 to 10 years of age at detection). 1,2 Prognosis has been ultimately poor in all previously reported cases, but here we describe a case in a horse that currently continues to successfully compete at a high level.…”

“…2 Navicular bone partition is generally not detected until well into a horse's working career (reported cases have ranged from 4 to 10 years of age at detection). 1,2 Prognosis has been ultimately poor in all previously reported cases, but here we describe a case in a horse that currently continues to successfully compete at a high level.…”