Scintigraphic evaluation of four dogs with protein-losing enteropathy using 111indium-labeled transferrin.

The purpose of this study was to determine the clinical utility of 111In-labeled transferrin (111In-TF) scintigraphy for evaluating dogs suspected of having protein-losing enteropathies. Four dogs were injected intravenously with autologous 111In-TF after 30 min incubation (at 37 degrees C) of 18.5 MBq (0.5 mCi) 111InCl3 with one ml of autologous plasma. Serial right lateral, left lateral and dorsal images were obtained 2, 4, and 24 hours post 111In-TF administration. Images were subjectively evaluated for the presence or absence of 111In-TF within the gastrointestinal tract. The results of total protein, albumin and globulin levels and results from gastrointestinal biopsies were recorded. In one dog, a follow-up scintigraphic study was done six months after initial evaluation and initiation of treatment for plasmocytic-lymphocytic enteritis. Gastrointestinal activity was noted by two hours in two dogs, while all four dogs had gastrointestinal activity on the 24 hour images. The mean (+/-std dev) plasma protein, albumin and globulin levels were 3.5 (+/-0.9), 1.7 (+/-1) and 1.8 (+/-0.3) respectively at the time of initial presentation. In the one dog that was evaluated after therapy, faint visualization of radioactivity within the colon was noted on the 24 hour image. Based on this study, 111In-TF appears to be a viable scintigraphic method for evaluating dogs with suspected protein-losing enteropathies. Potential limitations of this radiopharmaceutical include cost and prolonged isolation of the animal prior to release to the client due to the long physical half-life (T1/2 = 2.82 days).