Classification of portosystemic shunts entering the caudal vena cava at the omental foramen in dogs

Development of Three-Dimensional Anatomical Models of Dogs with Congenital Extrahepatic Portosystemic Shunts

The aim of this study was to develop three-dimensional anatomical models of dogs with congenital extrahepatic portosystemic shunts (CEPSs) using 3D printing, as well as to detail their development process and compare the final models to volume rendering (VR) derived from computed tomography (CT) scans. CT scans in the Digital Imaging and Communications in Medicine (DICOM) format of two canine patients were used-one with splenocaval deviation and the other with right gastrocaval deviation. The images were segmented using 3DSlicer software, generating 3D files in Standard Tessellation Language (STL) format, which were then subjected to refinement and mesh adjustment using Blender software. The models were printed on a J750™ Digital Anatomy™ printer, followed by post-processing in a 2% sodium hydroxide solution for 72 h, with subsequent rinsing to remove support resin residues. The printed models showed colored anatomical structures, including the liver; spleen; kidneys; part of the arterial, venous, and portal circulations; and CEPSs. For comparison purposes, VR of the scans was recreated in the RadiAnt DICOM Viewer software. Despite some limitations of the segmentation software, the 3D-printed models effectively represented the anatomy of the patients and the CEPSs, demonstrating good equivalence to the VR.

Single Posthepatic Portosystemic Shunt Communicated With Internal Thoracic Vein and Azygos Continuation of the Caudal Vena Cava in a Dog

Computed tomography angiography (CTA) was performed under general anaesthesia on a 7-month-old toy poodle that was referred with the chief complaints of salivation and neurological symptoms. The CTA revealed a rare form of posthepatic portosystemic shunt (PSS) via the suspected persistent left umbilical vein communicating with the internal thoracic vein in addition to an azygos continuation of the caudal vena cava (CVC). The patient underwent surgery for partial ligation of PSS on Day 4 after the initial examination. On Day 71, after the initial examination, a second surgery was performed for complete ligation. Approximately 10 years have passed since the patient's second surgery, and he is still healthy, and generally in good condition. Although the morphology of the shunt in this case was unusual and was accompanied by an azygos continuation of the CVC, a favourable course of treatment was obtained by ligating the shunt vessel. This case report suggests that CTA can reveal the complex morphological characteristics like our case. Surgical treatment in this case resulted in favourable progress, similar to that in dogs with commonly observed extrahepatic PSS.

Enlargement of the hepatic artery is present in dogs with a congenital extrahepatic portosystemic shunt and is independent of shunt insertion into the systemic circulation

The accurate diagnosis of portovascular anomalies has been facilitated by improvements in diagnostic imaging technology. In humans, hepatic arterial blood flow changes in response to the reduction in portal blood flow. The hepatic arterial buffer response characterizes an intrinsic regulatory mechanism in response to reduced portal venous blood flow, which results in hepatic arterial enlargement. At the authors' institution, enlargement of the hepatic artery has been anecdotally observed in a population of dogs with extrahepatic portosystemic shunting, consistent with previous literature that documents variability in hepatic arterial size. In this retrospective, blinded, analytical study, a hepatic artery:aorta (Ha:Ao) ratio was assessed on CT studies from 112 dogs, with (n = 43) and without (n = 69) an extrahepatic congenital portosystemic shunt in order to compare the hepatic artery size independent of body weight between the two populations. A significant increase in the Ha:Ao ratio was documented in dogs with an extrahepatic portosystemic shunt (EHPSS) compared with those dogs with no EHPSS independent of the location of shunt insertion into the systemic circulation (P < .001). Three cases had repeat CT after surgery, and all had Ha:Ao ratio reductions following treatment. The authors propose that this may be an additional imaging feature observed in dogs with an EHPSS.

Intramural esophageal location of a portosystemic shunt in a dog with two congenital portosystemic shunts on CT angiography

A 5-year-old male neutered pug with hematuria was presented to a referral hospital after identification of an extrahepatic portosystemic shunt (EHPSS) during abdominal ultrasonography. Computed tomographic-angiography revealed two anomalous blood vessels (left gastroazygous and left gastrophrenic). The left gastroazygous vessel followed an atypical path within the dorsolateral esophageal wall before entering the azygous vein. The morphology of this highly unusual vessel has not, based on the authors' review of the literature, been previously reported. In combination with a second anomalous vessel, this resulted in a unique presentation of an EHPSS. Computed tomography-angiography was essential for diagnosis and surgical planning in this case.

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.