Evaluation of ameroid ring constrictors for treatment for single extrahepatic portosystemic shunts in dogs: 168 cases (1995-2001)

OBJECTIVES: To evaluate use of an ameroid ring constrictor (ARC) for treatment for single extrahepatic portosystemic shunts (PSSs) and identify factors associated with postoperative death, continued portosystemic shunting, and long-term outcome in dogs. DESIGN: Retrospective study. ANIMALS: 168 dogs with a single extrahepatic PSS. PROCEDURE: Medical records of dogs that had a single extrahepatic PSS and were treated with an ARC were reviewed. Signalment, history, clinical signs, results of preoperative blood analyses and portal pressure measurements, PSS location, ARC size, postoperative complications, and postoperative scintigraphy results were recorded. Owners were interviewed 6 months to 6 years after surgery. Results-Postoperative complications developed in 10% of dogs. Postoperative mortality rate was 7.1%. Predictive factors for postoperative death included high preoperative WBC count and postoperative complications. Twenty-one percent of dogs in which portal scintigraphy was performed 6 to 10 weeks after surgery had continued shunting. Predictive factors for persistent shunting included low preoperative plasma albumin concentration, high portal pressure after complete occlusion, and high portal pressure difference (postocclusion minus baseline). Clinical outcome in 108 dogs was classified as excellent (80%), good (14%), or poor (6%). Predictive factors for excellent long-term clinical outcome included high preoperative plasma albumin concentration, low preoperative leukocytosis, low portal pressure after complete occlusion, absence of postoperative seizures, and absence of continued shunting. CONCLUSIONS AND CLINICAL RELEVANCE: Use of an ARC for treatment for a single extrahepatic PSS resulted in low morbidity and mortality rates. Certain preoperative factors were associated with increased risk of postoperative death, continued portosystemic shunting, and long-term outcome.