There are two patterns of increased radioisotope uptake in the navicular bone. 1) Focal central uptake generally seen in older show horses with equivocal  or classic radiographic changes. The focal nature of the uptake is more important than the actual intensity. 2) Mild to moderate uptake of the entire width of the navicular bone seen mostly in young race horses.  Radiographs are usually negative.

Incidental increased radioisotope uptake of the navicular bone is rare. The navicular bone is normally not seen.

               

There is moderate-intense radioisotope uptake involving the navicular bone.

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This horse became sound with an intra-articular coffin joint block.  Elective nuclear scintigraphy showed uptake of radiopharmaceutical in the navicular bone. Note the similarities in the radioisotope uptake in the lateral views of horses with active sidebone. Two views are the discriminating factors.

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Post scintigraphic radiographs revealed a fracture of the left hind navicular bone. Note that intensity of uptake is not necessarily relevant to the diagnosis. This may be an old fracture or a fracture occurring within 24-48 hours.  Radiographs were questionable. The right hind navicular bone is also abnormal in this case.

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Copyright 2001 University of Pennsylvania School of Veterinary Medicine
Faculty Sponsor: Dr. Michael W. Ross
Technologist: Vivian S. Stacy CNMT
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