Bone scans are a sensitive but non-specific imaging modality.  The technique uses bone seeking radionuclides that accumulate in bone lesions.  Images display areas of increased uptake of the radionuclide in the bone  commonly called "hot spots".  The accumulation of isotope indicated increased activity and blood flow  to the area.   The concentration of activity does not describe a specific pathology.   Radiographs generally require a 30% decalcification of bone to visualize a lesion.   Bone scans view bone tissue in the cellular level potentially enabling earlier visualization of a lesion.  The radio- active compounds are injected directly into the horses' jugular vein.  The primary rays are detected, enhanced and collected by a sophisticated network of electronics which produce an image.  The images can be viewed on a monitor, transferred to film or printed.