Portosystemic Vascular Anomalies
Metabolic/Digestive • Gene Not Determined • Complex
Summary
Portosystemic vascular anomalies (PSVAs) are congenital (present at birth) malformations of the blood vessels. In this condition, blood from the portal vein, which normally carries nutrients and toxins to the liver to be filtered, instead bypasses the liver and flows straight into the general circulation. This means toxins are not properly removed, which can lead to neurological and other health problems. Small breed dogs, such as Yorkshire Terriers, Maltese, Shih Tzus, and Miniature Schnauzers, are more likely to develop extrahepatic PSVAs (originating outside of the liver). Larger breeds like Labrador Retrievers and Irish Wolfhounds are more prone to intrahepatic PSVAs (originating inside of the liver). While no single genetic mutation has been identified, some breeds are predisposed to these blood vessel malformations.
Symptoms
Dogs with PSVAs may show signs early in life because their bodies cannot filter toxins properly. They may have nausea, vomiting, diarrhea, or grow more slowly than their littermates. Neurological signs can include confusion, vision problems, unusual behavior, or excessive vocalization. Some dogs also experience urinary issues, such as blood in the urine or bladder stones. The range and severity of symptoms can vary depending on the type of shunt and how much blood bypasses the liver.
Care
Treatment depends on the severity and location of the shunt. For extrahepatic shunts, surgery such as shunt ligation or the placement of special constricting devices is often recommended. Intrahepatic shunts generally require more complex surgical procedures. Some dogs can also be managed medically with special diets and medications to help reduce toxin build-up and control symptoms. Your veterinarian will determine the best course of treatment based on your dog’s individual needs.
Citations
Hayward, J., Castelhano, M., Oliveira, K. et al. Complex disease and phenotype mapping in the domestic dog. Nat Commun 7, 10460 (2016). https://doi.org/10.1038/ncomms10460
Review
19/08/2025 by Dr Robyn Bird
Breed
Akita, alaskan malamute, bearded collie, belgian sheepdog, belgian tervuren, berger picard, boerboel.