Case report of a seven-year-old horse with alterations of the navicular bone - clinical symptoms, radiology, computed tomography, and histologic examination

Fallbericht über Strahlbeinveränderungen bei einem 7-jährigen bayrischen Warmblutpferd - Klinik, Röntgen, Computertomographie und histologische Untersuchung

Schröer N, Niederacher V, Horstmann W, Hermanns W

DOI: 10.21836/PEM20000502
Year: 2000
Volume: 16
Issue: 5
Pages: 474-478

Clinical signs and diagnosis of a 7-year-old horse with multiple alterations of the navicular bone are described. The aim of this study was, to answer the question wether the observed alterations were a congenital disturbance of the development or an old remodelled fracture of the navicular bone. When introduced to the veterinarian the horse showed a severe lameness at the right forelimb with a sudden onset that lasted for six weeks. The pulse on the digital arteries was strong and bounding. Pressure applied to the distal aspect of the deep digital flexor tendon caused pain. The horse didn’t react to applied pressure with the hoof testers. On the dorsopalmar radiographic view of the navicular bone one or two horizontal „fracture lines“ lateral and medial to the sagittal ridge of the navicular bone were discovered. These alterations could be seen on three limbs. Post mortem computed tomography and histologic examination of two tripartite (forelimbs) and one bipartite (left hindlimb) navicular bones were performed. The histologic examination showed rounded edges of the separate pieces of the navicular bone with connective tissue in between. There were no signs of an acute inflammation. The deep digital flexor tendon had two outgrowths which fitted into the deepenings of the navicular bone. Because of the degnerative alterations of the navicular bone, the conclusion could be drawn that the alterations were of chronic nature. The question wether the alterations were a congenital disturbance of the development or an old remodelled fracture of the navicular bone could not be finally answered. It is supposed that if there exists more than one centre of ossification in the navicular bone an incapacity of ossification is possible.