MYOELECTRIC ACTIVITY OF THE ILEUM, CECUM, AND RIGHT VENTRAL COLON, AND CECAL EMPTYING OF RADIOLABELED MARKERS IN CLINICALLY NORMAL PONIES

Objectives-To determine normal cecal emptying curves for liquid-and so lid-phase radiolabeled markers and to further define myoelectric patte rns of the ileum, cecum, and colon in healthy ponies. Animals-8 adult ponies. Procedure-A cecal cannula and 12 bipolar Ag-AgCl recording ele ctrodes were sutured to the ileum, cecum, and right ventral colon of t he ponies. Radioisotopes, indium 111-labeled diethyltriaminepentaaceti c acid (In-111-DTPA) and technetium 99m (Tc-99m)-labeled sulfur colloi d bound to egg albumen, were introduced through the cannula directly i nto the cecal body. Movement of these markers from the cecum was monit ored by a gamma camera, and power exponential clearance curves were ge nerated. Myoelectric data were collected before and after IV administr ation of isotonic saline (0.9% NaCl) solution, and were analyzed for s pike burst (SB) rate, relative activity index, and mean burst duration . Myoelectric complexes were identified from observation of chart reco rdings or compressed, digitized data. Results-Clearance curves were ge nerated for liquid (In-111-DTPA)- and solid (Tc-99m)-phase markers. Ma rker types were not different with respect to lag phase, but liquid ma rkers emptied at a slightly faster rate than did solids. Baseline valu es were calculated after saline solution administration for each of th e myoelectric variables investigated. A relation between ileal, cecal, and colonic myoelectric activity was identified. Activity consistent with the previously described colonic migrating myoelectric complex in the pelvic flexure was identified in the right ventral colon. Conclus ions and Clinical Relevance-Baseline data on normal cecal emptying was obtained; this technique could be used to evaluate the effect of post ulated motility-modifying treatments used in equine practice.