Shunt portossistêmico congênito extra-hepático em um felino

Abstract

Portosystemic shunt is the most common hepatobiliary circulatory condition in the Small Animal Clinic, being more frequent in dogs but considered rare in cats. There are some variations in the presentation and sex predilection of this disease between the two species. Portosystemic shunts are vascular anomalies that consist of an abnormal connection between the portal circulation and the systemic circulation. They can be congenital or acquired and occur in either an extra-hepatic or intra-hepatic form. In the case of acquired shunt, it is a form of adaptation of the organism to relieve an increase in blood pressure in the portal circulation, originating from a primary disease. On the other hand, in congenital shunt, this anomaly leads to the diversion of blood flow from the spleen, stomach, pancreas, and intestines, which should pass through the liver, directly into the systemic circulation. As a result, various substances and toxins that should undergo hepatic metabolism are carried to other organ systems, causing damage to liver development and detrimental effects on the central nervous system — mainly due to the development of hepatic encephalopathy — urinary, and gastrointestinal systems. In diagnosing portosystemic shunts, the animal’s history and physical examination should be considered. Some hematological changes and urinalysis alterations may be observed, but imaging techniques such as ultrasound and computed tomography are the gold standard diagnostic methods. For the therapeutic approach to congenital shunts, there is a clinical approach aimed at managing clinical signs, particularly neurological, and a surgical approach, which is the only way to correct the shunt, with several techniques for addressing different types of shunts and varying attenuation times for the anomalous vessels. The present work aimed to report the case of a five-month-old male cat that was treated at the Veterinary Hospital of the Federal University of Minas Gerais (UFMG). The owners reported greater fragility and slower growth compared to other littermates, along with neurological signs such as prostration, balance disturbances, head tremors, stumbling gait, and particular features, including protruding tongue and amber-colored irises, a characteristic seen in some cats with congenital portosystemic shunt. Blood and urine tests were initially collected, and urinalysis revealed ammonium biurate crystals formed by excessive uric acid in the urine, leading to a suspicion of congenital portosystemic shunt. An ultrasound examination was performed, confirming the presence of a shunt, followed by a computed tomography scan to plan the surgical procedure. In this case, both clinical management and surgical attenuation with an ameroid constrictor were employed to manage the clinical signs and correct the shunt.