Canine intrahepatic portosystemic shunts: Interlobar and intralobar classifications

Area of Science:

• Veterinary Radiology
• Comparative Anatomy
• Surgical Pathology

Background:

• Canine congenital intrahepatic portosystemic shunts (IPSS) are vascular anomalies impacting liver function.
• Accurate classification of IPSS is crucial for effective treatment planning and prognosis.
• Current classification methods may lack consistency, necessitating improved descriptive criteria.

Purpose of the Study:

• To classify canine congenital intrahepatic portosystemic shunts (IPSS) based on their location: interlobar (within a liver fissure) or intralobar (within a liver lobe).
• To describe the imaging characteristics of normal canine ductus venosus (DV) anatomy using CT angiography (CTA).
• To determine the frequency and anatomical distribution of interlobar and intralobar IPSS in a cohort of dogs.

Main Methods:

• A two-part study combining a prospective anatomic assessment of normal canine liver morphology with CT angiography (CTA) and a retrospective multi-institutional case series of 56 dogs with IPSS.
• Normal canine liver anatomy and ductus venosus (DV) were reviewed via dissection and literature.
• Portal CTA data from dogs with single IPSS were analyzed to document shunt location (interlobar vs. intralobar) and origin.

Main Results:

• Intralobar IPSS were more common (57%) than interlobar IPSS (43%).
• Interlobar IPSS primarily originated from the left portal branch and were located craniodorsal to the porta hepatis.
• Intralobar IPSS predominantly arose from the right portal branch, located in the right-lateral liver lobe or caudate process.

Conclusions:

• Classifying canine congenital intrahepatic portosystemic shunts (IPSS) as interlobar or intralobar enhances descriptive consistency and diagnostic validity.
• Understanding the specific locations and origins of different IPSS types aids in accurate interpretation of portal CT angiography.
• This classification system provides a framework for more precise communication and research regarding canine portovascular anomalies.