Short- and long-term outcomes of 14 dogs with single congenital extrahepatic portosystemic shunts attenuated with a percutaneously controlled hydraulic occluder.

Abstract

Case history: Medical records from two veterinary referral centres were reviewed to identify dogs that underwent gradual attenuation with post-operative iterative inflation of a hydraulic occluder (HO) for treatment of a single congenital extrahepatic portosystemic shunt (CEHPSS) between 2013 and 2023. Median age at presentation of the dogs (n = 14) included in the study was 17 (min 10, max 26) months, and median body weight was 5 (min 4, max 9) kg.

Clinical and imaging findings: All dogs presented with clinical signs of hepatic shunt: nine with neurological signs, four with signs related to the gastrointestinal tract, and three with polyuria-polydipsia. Pre-prandial serum bile acid concentrations (BA) were above the reference range in all dogs. CEHPSS were characterised by CT angiography (CTA). Median hepatic volume and portal vein diameter to aorta diameter ratio (PV:A) were both below reference ranges.

Treatment and outcome: All dogs received medical treatment prior to surgery for a median time of 66 (min 44, max 94) days. All procedures were carried out by the same surgeon, with no intra-operative complications. Iterative percutaneous inflations of 25% of the total filling volume of the HO were scheduled to achieve gradual attenuation until the shunt was fully occluded. Complete shunt occlusion was obtained over a median time of 30 (min 21, max 35) weeks in all but two dogs, which showed partial occlusion at 73% and 77%, respectively. Major complications occurred in four cases, including HO cuff leakage (n = 3, between 8 and 25 months) and SC port shifting (n = 1, at 3 months). One dog was lost to follow-up 1.5 months after surgery, and one dog with cuff leakage died after revision surgery. Post-occlusion CTA performed in dogs without revision surgery (n = 11; median 12 (min 8, max 21) months after surgery) showed normalisation of liver volume, a statistical increase in PV:A compared to baseline, and a decrease in serum BA concentration in 5/9 cases. At a median of 67 (min 47, max 80) months after surgery, 10/11 cases (91%) had no clinical signs and 7/11 cases (64%) were receiving no medical treatment.

Clinical relevance: Gradual attenuation of a single CEHPSS in dogs with HO appears to be an effective method. However, poor implant reliability may prevent consistent occlusion and necessitate prolonged case monitoring after surgery, and revision surgery in some cases.