Use of transcolonic 99mtechnetium-pertechnetate as a screening test for portosystemic shunts in dogs

99mTechnetium-pertechnetate, when administered in high concentration into the colon, is rapidly absorbed across the colonic mucosa and results in a nuclear angiogram of the portal circulation. In normal dogs, a series of dynamic lateral scintigraphic images of the abdomen resulted in sequential visualization of the portal vein, liver, and several seconds later, the heart and lungs. In contrast, studies performed in 9 dogs with surgically confirmed portosystemic shunts demonstrated a different pattern of distribution, with heart and lung activity occurring before liver activity. In several cases, the aberrant shunt vessels could be identified. Studies were easy to perform, were well tolerated, and required no computer processing for interpretation.