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

Clinical signs and diagnosis of a 7-year-old hone 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 naviculor bone. Whe n 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 dista l aspect of the deep digital flexor tendon caused pain. The horse didn't re ad to applied pressure with the hoof testers. On the dorsopalmar radiographic view of the navicular bone one or two horiz ontal "fracture lines" lateral and medial to the sagittal ridge of the navi cular bone were discovered. These alterations could be seen on three limbs. Post mortem computed tomography and histologic examination of two triparti te (forelimbs) and one bipartite (left hind[imb) naviculor bones were perfo rmed. The histologic examination showed rounded edges of the separate piece s of the navicular bone with connective tissue in between. There were no si gns of an acute inflammation, The deep digital flexor tendon had two outgro wths which fitted into the deepenings of the navicular bone. Because of the degnerative alterations of the naviculor bone, the conclusion could be dro wn that the alterations were of chronic nature. The question wether the alt erations were a congenital disturbance of the development or an old remodel led fracture of the navicular bone could not be finally answered. It is sup posed that if there exists more than one centre of ossification in the navi cular bone on incapacity of ossification is possible.