Evaluation of ameroid ring constrictors for the management of single extrahepatic portosystemic shunts in cats: 23 cases (1996-2001)

Objective-To document the signalment; history; clinical signs; clinicopathologic, diagnostic imaging, and surgical findings; perioperative complications; and long-term clinical results of ameroid ring constrictor (ARC) placement on single extrahepatic portosystemic shunts (PSS) in cats, Design-Retrospective study. Animals-23 cats treated with an ARC on a single extrahepatic PSS. Procedure-An ARC was placed surgically around the PSS. Portal pressure was measured prior to ARC placement, with complete temporary PSS occlusion, and after ARC placement. Cats were scheduled for recheck transcolonic portal scintigraphy 8 to 10 weeks after surgery. Follow-up information was obtained by telephone interview with the owners. Results-An ARC was successfully placed in 22 of 23 cats. Intraoperative complications, consisting of PSS hemorrhage, occurred in 2 cats. Mean ( SD) portal pressure (n = 15 was 6.7 +/- 2.9 mm Hg before PSS manipulation, 18.6 +/- 7.7 mm Hg with complete temporary PSS occlusion, and 6.9 +/- 2.7 mm Hg after ARC placement. Postoperative complications developed in 77% (17 of 22) of cats after ARC placement, and included central blindness, hyperthermia, frantic behavior, and generalized motor seizures. Perioperative mortality rate was 4.3% (1 of 23). Persistent shunting was identified in 8 of 14 cats. Overall, 75% (15 of 20) of cats had an excellent longterm outcome. Conclusions and Clinical Relevance-Placement of an ARC on single extrahepatic PSS in cats resulted in low surgical complication and perioperative mortality rates, but most cats did have substantial postoperative complications. Persistent shunting was common, although many cats with persistent shunting were clinically normal.