• Lameness that cannot be localised
and/or multiple limb / shifting lameness.
• Lameness that can be blocked but
no radiographic changes are seen.
• An uncooperative horse where it
would be dangerous to attempt diagnostic analgesia.
• Back and proximal limb problems.
The advantage of nuclear
scintigraphy over radiography is that
it provides a physiological or metabolic assessment of the bone in contrast
to an anatomic or morphological assessment. As a result nuclear bone imaging
is more sensitive to localising and quantifying dynamic bone change before
these changes may be seen on radiographs. However this may also result in
some false positive results being detected and any findings should be
interpreted with clinical findings and
other diagnostic procedures.
It is possible that the inflammation that occurs as a result of
injection of local anesthetics in performing diagnostic analgesia may
interfere with scintigraphic findings, particularly with regard to joint
blocks.Therefore it may be advised
that scintigraphy is delayed for 2-3 weeks after performing diagnostic analgesia.
As a general rule the overall
uptake in younger horses is better than older horses and in Thoroughbreds and
light breeds is better than in heavy draft breeds or warmbloods. There may be
individual variation with lower uptake in one limb compared to the
contra-lateral limb or lower uptake in both limbs below the carpus or the
hock. We bandage the limbs and where appropriate lunge the horse prior to
performing the scan to compensate for this..
It should be borne in mind that
about 50% of chronic lameness cases will have negative scintigraphic findings
due to lack of sufficient bone turnover at the site of pathology.
