This condition is often congenital; it occurs because the portal vessel that do not close after birth and therefore, blood bypasses the liver, which allows for an over-accumulation of toxic substances in the circulation due to the inability of the liver to filter toxins
This condition occurs more commonly in dogs than cats; and certain breeds of dogs are more predisposed- such as Maltese and Yorkies, for example. There are also different types of shunts – extrahepatic are more common in small breeds while intrahepatic shunts are more common in larger breeds
Clinical signs may vary; however, the most common signs in young animals are poor growth, difficulty gaining weight, GI, skin issues and neurologic signs due to hepatic encephalopathy. Clinical signs may wax/wane. Your vet may recommend additional testing, such as bile acids or advanced imaging if they suspected a liver shunt based on physical exam or labwork findings
This condition can be treated medically in some cases; this may include a diet change, for example, as well as medications such as lactulose and antibiotics, for example. However, most patients have a better prognosis with surgery to ligate the shunt
1)Veterinary Partner. Veterinarypartner.com
2)Tilley, L. P., & Smith, F. W. (2005). The 5-minute veterinary consult: Canine and feline. Philadelphia: Lippincott Williams & Wilkins.
3)Yin, S. A. (2010). The small animal veterinary nerdbook. Davis, CA: CattleDog Pub.