Evaluation of solid phase radiolabels of dog food for gastric emptying

99mTc‐Pertechnetate, 99mTc‐mebrofenin, 99mTc‐disofenin, 99mTc‐sulfur colloid, and 99mTc‐Dowex resin beads were evaluated for in vitro stability as a label for both dry extruded, and canned dog food for gastric emptying scintigraphy. A sample of each radiolabeled diet was added to water, gastric juice, intestinal juice, or gastric juice followed by intestinal juice for in vitro digestion. After a 3‐hour digestion period, tubes were centrifuged and percentage solid phase retention (%SPR) was calculated. The experiment was repeated three times over a 14‐day period to minimize day‐to‐day variation. For dry dog food, 99mTc‐mebrofenin and 99mTc‐disofenin had similar %SPR in water (96 and 93%, respectively) and gastric juice (>95% each) and were significantly higher than other labels. For canned dog food, mebrofenin had a 91% SPR for the water or gastric juice digestions, and 99mTc‐Dowex had a %SPR of >99%. 99m Tc‐mebrofenin and 99mTc‐Dowex were also tested in vivo, where 99mTc‐Dowex had poor stability, and 99mTc‐Mebrofenin had excellent stability.99mTc‐Mebrofenin is a suitable label for dog food for gastric emptying scintigraphy.