Relevance of bone imaging and x-ray examination in the area of navicular diseases

Bone imaging allows the demonstration of the actual metabolism of the equine pedal and navicular bone. With bone scintigraphy the activity within areas showing radiographic changes can be evaluated. 86 young horses were repeatedly scaned in order to establish the value of bone scanning. Besides a very good correlation of clinical, radiological and scintigraphic findings in most horses a number of cases were observed with increased uptake of the navicular bone but missing radiographic and clinical signs. A number of these horse actually developed podotrochlosis but the rest did not. This behaviour is explained by the physiological adaption of the bone metabolism to changing loads, in a new retrospective study the increased-uptake of the navicular bone in horses with persisting lameness but lacking radiograhic alterations was further investigated. Intensive focal tracer accumulation in the navicular bone, which also can be observed in the lateral view, was mainly observed in chronically lame horses. The irritation of the navicular bone metabolism can be considered as a pathological sign in certain occasions. Periodic re-examination of these cases is advised.