Unusual haemodynamics in two dogs and two cats with portosystemic shunt - implications for distinguishing between congenital and acquired conditions

Abstract

Extrahepatic porto-systemic shunt (PSS) in small animals can be congenital (CPSS) or acquired (APSS) as a consequence of portal hypertension (PH), and are distinguished on the bases of their anatomical pattern. A precise morphologic imaging assessment, along with clinical and histopathologic findings, is important for distinguishing patients with PH from those with congenital PSSs, which require different therapeutic approach. Expected findings in patients with PH are presence of ascites, multiple APSS, and a confirmed cause of portal flow obstruction. On the other hand, a single PSS, absence of ascites and no evidence of portal vein, caudal vena cava or hepatic disorders are typical findings of CPSS patients. This paper describes four cases of PSSs in which the combination of the computed tomographic imaging findings did not match the standards for APSS nor for CPSS: one dog had chronic hepatitis causing PH and ascites and a splenoazygos PSS, to date considered a CPSS pattern. One dog showed a left splenogonadal PSS and porto-caval varices, to date considered an APSS pattern, without ascites, portal vein obstruction, primary structural hepatic disorders nor evidence of PH. Two cats, with and without diffuse hepatic structural disorders respectively, had a single left splenogonadal PSS without ascites. Possible interpretation of such unusual haemodynamic conditions and clinical repercussion, especially for orientation of treatment choice, are discussed.

Internal thoracic veins: Anatomy, plasticity and clinico-imaging relevance in small animal practice

“…The spleno-azygos APSS has been described both in humans and small animals but its real origin and differentiation from a simple enlargement of the left gastric and oesophageal veins (cardiac branches of the left gastric vein and oesophageal branches of the azygos vein) is still debated [3,10].…”

“…Despite several descriptions of collateral venous pathways involving the azygos vein having been published in the veterinary literature [2,10], limited information is available on the possible involvement of the internal ITVs. Nowadays, the wide availability of computed tomography angiography (CTA) from multidetector-row CT (MDCT) scans in veterinary practice provide exhaustive depictions of large and small vessels throughout the whole body, allowing assessment of increasingly fine vascular anatomical details until now under-investigated.…”

Clinical characteristics of, prognostic factors for, and long-term outcome of dogs with multiple acquired portosystemic shunts: 72 cases (2000–2018)

“…5,6,15,18,19 Dogs with MAPSSs can have a history of neurologic (eg, abnormal mentation, hepatic encephalopathy, or seizures), gastrointestinal tract (eg, inappetence, diarrhea, vomiting, or weight loss), or urinary tract (eg, polyuria and polydipsia) abnormalities. 7,[20][21][22][23] Common hematologic and biochemical changes include microcytic, hypochromic anemia; high liver enzyme activities; low glucose, BUN, albumin, and cholesterol concentrations; hyperammonemia; and high pre-and postprandial bile acids concentrations. 7,20,23…”

“…7,[20][21][22][23] Common hematologic and biochemical changes include microcytic, hypochromic anemia; high liver enzyme activities; low glucose, BUN, albumin, and cholesterol concentrations; hyperammonemia; and high pre-and postprandial bile acids concentrations. 7,20,23…”

“…Visualization of multiple, extrahepatic, tortuous vessels near the kidneys is characteristic of MAPSSs seen during exploratory laparotomy. 7,15,[20][21][22][23][24] Computed tomographic angiography, trans-splenic portal scintigraphy, and contrast-enhanced portal magnetic resonance angiography are all well-described modalities in diagnosing MAPSSs. [25][26][27][28][29][30] Diagnosis of MAPSSs with trans-splenic portal scintigraphy is based on the identification of several discrete anomalous vessels in various locations, hepatofugal blood flow caudal to the cranial margin of the kidneys, or evidence of bolus fragmentation.…”