Evaluation of Intraperitoneal Injection Accuracy

Following CHB, each animal was carefully removed from the chamber and positioned in dorsal recumbency for necropsy examination. The skin was incised along the midline and the injection site was identified in the abdominal wall musculature. The abdominal wall was incised and the intestines were reflected out of the abdominal cavity. Distribution of blue injectate and any misinjection into hollow viscera were noted. The liver was reflected cranially and any presence of dye within the biliary vessels caused by uptake of injectate from the peritoneal cavity and subsequent biliary excretion was noted. The GIT from the cardia to the descending colon was removed and any intestinal segments with dye-stained serosa were opened to confirm or rule out intraluminal misinjection. Misinjection was defined as the presence of blue injectate within hollow viscera or subcutaneous tissues, or staining the fur. For each rat, the serosal surfaces of the abdominal wall injection site, the caudate liver lobe, and transverse sections of at least three intestinal sections were examined histologically after formalin fixation for evidence of acute inflammation or swelling of mesothelial cells. Evaluation was performed by a single board-certified veterinary pathologist (CK), who was blinded to treatment group assignments.