Received: 9 March 2020 Revised: 22 July 2020 Accepted: 22 July 2020 DOI: 10.1111/vru.12914 ORIGINAL INVESTIGATION CT angiography identifies collaterals in dogs with splenic vein obstruction and presumed regional splenic vein hypertension Swan Specchi 1, 2 Giovanna Bertolini 3 1 Ospedale Veterinario i Portoni Rossi, Anicura, Bologna, Italy 2 Antech Imaging Service, Fountain Valley, California 3 San Marco Veterinary Clinic and Laboratory, Diagnostic and Interventional Radiology Division, Veggiano, Padova, Italy Correspondence Giovanna Bertolini, DVM, Ph.D, Doctor Europaeus the Diagnostic and Interventional Radiology Division of San Marco Veterinary Clinic and Laboratory, Veggiano, Padova, Italy. Email: bertolini@sanmarcovet.it Abstract Occlusion of the splenic vein, without occlusion of the portal vein, can lead to a local- ized, regional splenic hypertension, referred as sinistral or left-sided portal hyperten- sion in the human radiology literature. In people, may cause gastrointestinal hemor- rhages from the esophageal and gastric varices and the primary pathology usually includes pancreatitis and pancreatic neoplasms. The final diagnosis of localized splenic hypertension necessitates accompanying normal liver functions and a patent extrahep- atic portal vein. Following obstruction, the resultant elevated splenic bed venous pres- sure causes formation of collateral routes, the extent of which depends upon the level and degree of obstruction. In this retrospective descriptive study, authors assessed the collateral pathways in dogs with isolated splenic vein occlusion and possible regional splenic vein hypertension. Out of the 46 patients initially recruited, 25 were excluded due to the presence of concomitant portal thrombosis and direct/indirect CT signs of portal hypertension. The remaining 21 dogs had clinicopathological tests suggest- ing normal liver function. The causes of obstruction identified included splenic pedi- cle torsion, tumoral splenic vein invasion, and splenic vein thrombosis. Four of 21 dogs with isolated splenic vein obstruction showed collateral pathways through the left gas- troepiploic vein (4/4), left gastric vein (2/4), and splenogonadal vein (1/4). The diagnosis of isolated, regional splenic hypertension should be based on clinical, biochemical, and radiological evaluation. Computed tomography is an excellent tool to assess the collat- eral patterns and to determine the underlying cause. 1 INTRODUCTION The splenic vein (SV) is the major tributary of the portal venous sys- tem in mammals. Isolated occlusion of the SV (without occlusion of the portal vein) can lead to localized portal hypertension, called sinistral portal hypertension in the radiology literature. 1–3 Other names that have been used in the radiology literature include left-sided, spleno- portal, regional, segmental, localized, compartmental, or linear portal Abbreviations: crPDV, cranial pancreaticoduodenal vein; ltGV, left gastric vein; PV, portal vein; SV, splenic vein. Conflict of interest disclosure: The authors declare that there are no conflict of interest. EQUATOR network disclosure: The study followed the STROBE-VET reporting guidelines. hypertension. 3 Sinistral portal hypertension is considered a misnomer given the normal pressure in the portal vein in these patients. 3 To avoid misunderstanding, in this manuscript authors will use the term regional SV hypertension to refer to this condition. As a result of the isolated SV obstruction, a collateral circulation is established, the extent of which depends upon the level and degree of obstruction. 4 SV hypertension in people is mainly caused by pancreatic diseases such as acute or chronic pancreatitis, pancreatic pseudocysts, and pancreatic carcinomas. 5 Patients may present with splenomegaly and upper gastrointestinal hemorrhage from isolated gastric varices. 3 Importantly, regional SV hypertension differs from other forms of por- tal hypertension in that liver function is often preserved and a patent extrahepatic portal vein is present. 1 Vet Radiol Ultrasound. 2020;1–5. © 2020 American College of Veterinary Radiology 1 wileyonlinelibrary.com/journal/vru