Congenital portosystemic shunt (CPSS) diagnosis begins with liver function tests, with paired serum bile acids (SBA) as the best test to exclude the diagnosis and fasting ammonia (FA) as the best combined screening test. FA has a sensitivity of 77.4% and specificity of 93.3% for diagnosing CPSS, while paired SBA achieves 100% sensitivity and 100% negative predictive value, making a normal paired SBA result sufficient to rule out CPSS in a suspected case.Veterinary Reco… Abdominal ultrasound (aUS) has a sensitivity of 80.8% and specificity of 90.0%, but fails to visualize the shunt in approximately 20% of cases and is particularly unreliable for extrahepatic shunts not inserting into the prehepatic caudal vena cava.Veterinary Reco…
When clinical suspicion remains after initial bloodwork, advanced imaging is required for anatomic confirmation and surgical planning. Computed tomography angiography (CTA) has a sensitivity of 96% and specificity of 89% for detection of extrahepatic PSS.BMC Veterinary… Portography remains the gold standard for portal system visualization but is being replaced by CTA, MRI, and ultrasonography in most centers.BMC Veterinary… Nuclear scintigraphy, ultrasound, CT, and MRI are all accepted modalities for confirming intrahepatic portosystemic shunt (IHPSS) diagnosis and classifying shunts as left, right, or central divisional.Journal of the…
A machine learning model using routine CBC and chemistry data achieves a sensitivity of 94.3% and specificity of 90.5% for diagnosing any PSS, with mean corpuscular hemoglobin, lymphocyte count, and serum globulin concentration as the most predictive variables.Frontiers in Ve… This tool is best used as a pre-imaging screening step to raise or lower index of suspicion before committing to advanced imaging.Frontiers in Ve…
Shunt morphology influences clinical presentation and should guide diagnostic suspicion. Dogs with portocaval (PC) shunts present significantly younger, with lower body condition scores, more severe clinical signs, more pronounced microcytosis and monocytosis, lower urea and creatinine, and higher preprandial SBA and fasting ammonia compared to dogs with portophrenic (PP) shunts.Journal of the… Dogs with portoazygous (PA) and PP shunts are diagnosed at an older age than those with PC shunts.Journal of the… In older dogs with mild or atypical signs, PP shunts — which are more difficult to detect on ultrasound — should be specifically screened for.Journal of the… Miniature Schnauzers are diagnosed with extrahepatic PSS (EHPSS) after 7 years of age more frequently than other breeds, and dogs with portoazygous morphology may present later due to intermittent reductions in shunt fraction.Journal of the…
Surgical attenuation is the treatment of choice for both EHPSS and IHPSS, as long-term medical management is substantially less effective than surgery and is reserved for cases with prohibitive anesthetic risk, challenging shunt morphology, owner financial constraints, or mild clinical signs only.Journal of Vete…+1 Long-term clinical outcome after surgical techniques is clearly superior to medical management alone, though this difference only becomes evident at longer follow-up (median 1,936 days versus 579 days).Journal of Vete… Dogs ≥5 years of age at diagnosis have better long-term outcomes with surgical attenuation than with medical management alone.Journal of the…
Medical management targets ammonia reduction and is used for preoperative stabilization or as sole therapy when surgery is declined. This consists of lactulose, metronidazole to reduce colonic bacterial load, and a hepatic support diet.Journal of the…
For EHPSS, gradual occlusion devices are preferred over acute complete ligation to allow the portal vasculature time to adapt to increased blood flow and reduce the risk of fatal portal hypertension.Journal of the…+1 Ameroid constrictor is statistically superior to thin film band for achieving EHPSS closure (P = .003); no other pairwise comparisons among surgical techniques have reached statistical significance.Journal of Vete… Cellophane banding induces gradual occlusion via inflammation and thrombosis, with shunt occlusion potentially taking more than 6 months depending on vessel size.BMC Veterinary… Overall surgical mortality rates range from 0% to 32% depending on technique, shunt location, and degree of narrowing.Journal of Vete…
For IHPSS, percutaneous transvenous coil embolization (PTCE) is a well-established minimally invasive alternative to open surgery, with success rates equivalent to cellophane banding.Journal of the… Open surgical techniques for IHPSS have historically carried perioperative complication rates up to 77% and mortality rates up to 28%.Journal of the… PTCE has perioperative complication and mortality rates similar to or better than open surgical techniques.Journal of the… Right and central divisional IHPSSs are particularly challenging for open surgery due to short hepatic veins partially covered by parenchyma, making PTCE especially advantageous for these subtypes.Journal of the… Gastroduodenal ulceration and erosion occurs in up to 21% of dogs with IHPSS undergoing PTCE and can occur both before and after treatment, independent of NSAID use.Journal of the…
Portal hypertension is the critical intraoperative and postoperative complication to avoid, defined as portal pressure >10 mmHg.Journal of Vete… It manifests as ascites, development of multiple acquired portosystemic shunts (MAPSS), or hemodynamic shock.Journal of Vete… MAPSS must be distinguished from a single congenital EHPSS preoperatively — MAPSS appear as multiple tortuous vessels on imaging, in contrast to the single vessel of a congenital shunt.Journal of the…
Postoperative assessment of shunt closure should use fasting blood ammonia as the primary functional test, as preprandial and postprandial SBA frequently remain elevated after complete ligation even in dogs without residual shunting.Journal of Vete… The lidocaine/monoethylglycylxylidide (MEGX) test is a promising noninvasive adjunct: at 15 minutes post-injection (1 mg/kg IV lidocaine), a MEGX concentration of 33.73 ng/mL (median) in dogs with closed EHPSS versus 13.74 ng/mL at diagnosis achieves a sensitivity of 96.2% and specificity of 82.8% for confirming shunt closure.Journal of Vete… For imaging-based assessment after cellophane banding, CTA has variable sensitivity (50–100%) and specificity (57–85%) at 3 months post-surgery, while splenoportography shows substantially better inter-rater agreement.BMC Veterinary… At 2–6 months post-surgery, 85% of dogs show normal liver function.BMC Veterinary…
| Test / Technique | Protocol | Performance | Key Caveat |
|---|---|---|---|
| Fasting ammonia (FA) | Single fasted sample | Sensitivity 77.4%, specificity 93.3% | Best combined screening test Veterinary Reco… |
| Paired serum bile acids (SBA) | Pre- and postprandial | Sensitivity 100%, NPV 100% | Best test to exclude cPSS Veterinary Reco… |
| Abdominal ultrasound | Standard abdominal US | Sensitivity 80.8%, specificity 90.0% | Misses ~20% of cases; unreliable for some EHPSS Veterinary Reco… |
| CT angiography (CTA) | Contrast-enhanced multidetector CTA | Sensitivity 96%, specificity 89% for EHPSS detection | Variable performance for post-treatment residual flow assessment BMC Veterinary… |
| Machine learning model | CBC + chemistry panel | Sensitivity 94.3%, specificity 90.5% | Subtype classification accuracy only 85.7% Frontiers in Ve… |
| Lidocaine/MEGX test | 1 mg/kg IV lidocaine; MEGX at T15 | Sensitivity 96.2%, specificity 82.8% for shunt closure | Validated for EHPSS post-attenuation only Journal of Vete… |
| Ameroid constrictor (EHPSS) | Gradual occlusion device | Superior to thin film band for closure (P = .003) | No significant difference vs. other techniques Journal of Vete… |
| PTCE (IHPSS) | Percutaneous transvenous coil embolization | Equivalent to cellophane banding | GUE in up to 21% pre- and post-procedure Journal of the…+1 |
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