Summary Reasons for performing study : Most current models of visceral sensitivity testing in the horse have required visceral cannulation. Colorectal distention (CRD) is a widely used, noninvasive method for testing in other species and could be adapted for use in horses. Objectives : To develop a protocol of controlled CRD in the conscious horse and to evaluate the effect of i.v. xylazine or intrarectal lidocaine on CRD threshold and rectal compliance. Methods : Eight horses were used for baseline studies (3 trials each) and 6 horses to evaluate treatments (4 trials, 2 per treatment). A 45 cm diameter polyvinyl balloon attached to plastic tubing was used for rectal distention following a stepwise barostat‐controlled inflation pattern. Results : The procedure was well tolerated by all horses. Mean baseline threshold pressure was 14.17 mmHg. Xylazine i.v. resulted in significantly (P<0.05) higher mean threshold pressures compared to baseline or rectal lidocaine. Rectal compliance increased following lidocaine treatment relative to baseline or xylazine. Conclusions : CRD offers a noninvasive method for visceral sensitivity testing in the horse. Xylazine raises CRD threshold, while lidocaine increases rectal compliance. Potential relevance : The increased rectal compliance following intrarectal lidocaine administration may explain the benefit of its use to facilitate rectal examination.
Abstract Objectives To determine normal cecal emptying curves for liquid- and solid-phase radiolabeled markers and to further define myoelectric patterns of the ileum, cecum, and colon in healthy ponies. Animals 6 adult ponies. Procedure A cecal cannula and 12 bipolar Ag-AgCl recording electrodes were sutured to the ileum, cecum, and right ventral colon of the ponies. Radioisotopes, indium 111-labeled diethyltriaminepentaacetic acid ( 111 In-DTPA) and technetium 99m ( 99m Tc)-labeled sulfur colloid bound to egg albumen, were introduced through the cannula directly into the cecal body. Movement of these markers from the cecum was monitored by a gamma camera, and power exponential clearance curves were generated. Myoelectric data were collected before and after IV administration of isotonic saline (0.9% NaCl) solution, and were analyzed for spike burst (SB) rate, relative activity index, and mean burst duration. Myoelectric complexes were identified from observation of chart recordings or compressed, digitized data. Results Clearance curves were generated for liquid ( 111 In-DTPA)- and solid ( 99m Tc)-phase markers. Marker types were not different with respect to lag phase, but liquid markers emptied at a slightly faster rate than did solids. Baseline values were calculated after saline solution administration for each of the 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. Conclusions and Clinical Relevance Baseline data on normal cecal emptying was obtained; this technique could be used to evaluate the effect of postulated motility-modifying treatments used in equine practice. ( Am J Vet Res 1998;59:313–319)
SUMMARY Five 5 to 6 month old horses were surgically prepared with silver electrodes sutured to the serosa of gastric antrum, duodenum and proximal portions of the jejunum. Normal migrating motility complex ( mmc ) periodicity was determined during daytime hours in horses that were fed and horses from which food was withheld for 24 hours. Periodicity was defined as time span from the end of one period of regular spike activity ( rsa ) to the end of the next rsa in the mmc . The periodicity was 120.5 ± 9.5 ( sem ) minutes in horses from which food was withheld, and was 125.7 ± 20.3 minutes in horses fed hay free choice. Coincident with each duodenal rsa , antral spike activity ceased. Xylazine (0.25 and 0.5 mg/kg), given IV during the period of intermittent spike activity of the mmc to either fed or unfed horses induced, within 2 minutes, a rsa complex in the duodenum that migrated to the proximal portion of the jejunum. This was followed by a period of no spike activity of normal duration, which proceeded on to a period of intermittent spike activity of varying duration to complete the mmc cycle. Pretreatment iv administration of an α 2 -adrenergic antagonist, tolazoline (1 mg/kg) also provoked a rsa complex, but blocked the xylazine effect. The results indicated that xylazine resets the duodenal mmc in the horse, but does not seriously disrupt proximal gastrointestinal tract motility, and that control of mmc periodicity in this region probably involves more than α 2 -adrenergic receptors.
Summary Equine gastrointestinal motility is a central issue in cases of equine colic, post operative convalescence and alimentary conditions encountered in practice. There are significant syndromes of intestinal dysmotility in the horse such as obstructive disorders and post operative ileus that are still poorly understood. This review describes the various areas of research that aim to elucidate the pathogenesis of intestinal hypo‐ or hypermotility by research methods, which include studies at the cellular level, and those that employ in vitro or in vivo techniques of evaluating the physiology and mechanical means of ingesta transit through the alimentary tract. The review discusses future directions for studies which will hopefully lead to better understanding and appropriate measures for diagnosis, therapy and prevention of ileus and other motility disorders.
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)