INTRAHEPATIC VENOUS COLLATERALS PREVENTING SUCCESSFUL STENT-SUPPORTED COIL EMBOLIZATION OF INTRAHEPATIC SHUNTS IN DOGS

Congenital Portosystemic Shunts in Dogs and Cats: Treatment, Complications and Prognosis

Congenital portosystemic shunts (CPSS) are a common vascular anomaly of the liver in dogs and cats. Clinical signs of CPSS are non-specific and may wax and wane, while laboratory findings can raise the clinical suspicion for CPSS, but they are also not specific. Definitive diagnosis will be established by evaluation of liver function tests and diagnostic imaging. The aim of this article is to review the management, both medical and surgical, complications, and prognosis of CPSS in dogs and cats. Attenuation of the CPSS is the treatment of choice and may be performed by open surgical intervention using ameroid ring constrictors, thin film banding, and partial or complete suture ligation or by percutaneous transvenous coil embolization. There is no strong evidence to recommend one surgical technique over another. Medical treatment strategies include administration of non-absorbable disaccharides (i.e., lactulose), antibiotics, and dietary changes, and are indicated for pre-surgical stabilization or when surgical intervention is not feasible. After CPSS attenuation, short- and long-term post-surgical complications may be seen, such as post-operative seizures and recurrence of clinical signs, respectively. Prognosis after surgical attenuation of CPSS is generally favorable for dogs and fair for cats.

Imaging findings in a minipig with congenital portosystemic shunt

A 15-month-old, male minipig was presented with a clinical history of seizure activity for one year. The minipig was the smallest among the littermates and was referred due to an elevated blood ammonia level with suspected portosystemic shunt (PSS). Ultrasound and CT angiography were consistent with a congenital extrahepatic PSS. To the author’s knowledge, this is the first description of a congenital extrahepatic PSS diagnosed by ultrasound and contrast-enhanced computed tomography in a minipig (pig). Partial shunt closure was performed by interventional stent application.

Intrahepatic venous collaterals in dogs with congenital intrahepatic portosystemic shunts are associated with focal shunt or hepatic vein narrowing

Dogs with congenital intrahepatic portosystemic shunts (IHPSS) occasionally have multiple smaller intrahepatic, tortuous blood vessels surrounding the primary shunt. This study was a retrospective, observational design that was also descriptive and anatomic in nature. Objectives were to characterize vascular morphology in IHPSS dogs presenting with intrahepatic venous collaterals (IVCs) relative to IHPSS dogs without IVCs, and to propose reasons for IVC development. The authors hypothesized that (a) IVCs develop secondary to flow resistance around a focal area of a shunt or draining hepatic vein narrowing and (b) the presence of IVC is associated with portal vessel development before intervention. Anonymized CT angiograms (CTA) and fluoroscopic portovenograms (FPV) of dogs with IHPSS were evaluated for the presence of IVCs, focal narrowing within the IHPSS, and intrahepatic portal vessels >5 mm long. Eleven of 47 (23%) dogs had IVCs identified. IVCs were significantly associated with focal narrowing in the shunt or draining hepatic vein on CTA (P = 0.039) and FPV (P = 0.021). IVCs were not associated with the presence of intrahepatic portal branches >5 mm long on portovenography (P = 0.42) or CTA (P = 0.49). Focal narrowing in the shunt (circumferential soft tissue narrowing >20% of the shunt diameter) was significantly associated with intrahepatic portal branches >5 mm long on both modalities (P < 0.001). IVCs are associated with focal narrowing of the shunt or draining hepatic vein in dogs with IHPSS. IVC should be distinguished from other conditions when evaluating a CTA for canine IHPSS.

Endovascular evaluation and treatment of intrahepatic portosystemic shunts in dogs: 100 cases (2001-2011)

OBJECTIVE

To evaluate short- and long-term outcome following endovascular treatment of intrahepatic portosystemic shunts in dogs.

DESIGN

Retrospective case series.

ANIMALS

100 dogs.

PROCEDURES

All patients had angiographic evaluation with or without endovascular shunt attenuation. The medical records were reviewed for pertinent data, complications, outcome, and survival time.

RESULTS

95 dogs with congenital intrahepatic portosystemic shunts received 111 procedures (83% [79/95] had 1 treatment, and 17% [16/95] had > 1 treatment; 5 dogs had no treatment because of excessive portal venous pressure-central venous pressure gradients). Angiography identified 38 right, 33 left, and 19 central divisional single shunts (n = 90) and 10 complex or multiple shunts. Partial shunt attenuation was performed in 92 dogs by means of caval stent placement and insertion of thrombogenic coils within the shunt, and 3 had complete acute shunt occlusion. Major intraoperative complications (3/111 [3%]) included temporary severe portal hypertension in 2 dogs and gastrointestinal hemorrhage in 1 dog. Major postoperative (< 1 week after surgery) complications (14/111 [13%]) included seizures or hepatoencephalopathy (7/111 [6%]), cardiac arrest (2/111 [2%]), jugular site bleeding (2/111 [2%]), pneumonia (1/111 [1%]), suspected portal hypertension (1/111 [1%]), and acute death (1/111 [1%]). Median follow-up time was 958 days (range, 0 to 3,411 days). Median survival time for treated dogs was 2,204 days (range, 0 to 3,411 days). Outcome was considered excellent (57/86 [66%]) or fair (13/86 [15%]) in 70 of 86 (81%) treated dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that endovascular treatment of intrahepatic shunts in dogs may result in lower morbidity and mortality rates, with similar success rates, compared with previously reported outcomes for open surgical procedures. Gastrointestinal ulceration was a common finding among this population of dogs, and lifelong gastroprotectant medications are now recommended.