Nuclear scintigraphy (sometimes known as "bone scanning") is an invaluable diagnostic tool in some lameness cases. It is particularly useful in cases where nerve blocks have not revealed the source of the lameness, when other imaging techniques have not shown any abnormalities, in cases of multi-limb lameness and in difficult to image areas such as the pelvis. It is mainly used for imaging bones, although vascular and soft tissue phases are also possible.
The procedure involves injecting the horse with a radioactive "dye" (technetium 99), which is taken up by areas of increased bone activity. Shortly after this a special camera is used to detect the radioactivity produced and provide detailed images of the skeleton. It is particularly useful to identify stress fractures, abnormal stress modelling and to monitor fracture healing. It is also very useful in assessing some cases of back and neck pain.
Although it is well known to be a safe procedure, after injection and imaging the horse is kept in controlled conditions for twenty four hours to comply with radiation safety regulation requirements. Horses are generally allowed to leave the hospital the day after imaging, but sometimes the technique identifies problems which require further investigation. This must be done the next day to avoid unnecessary handling when the radioactivity levels are relatively high.