Hepatic syndromes in dogs

Abstract

The liver plays a critical role in maintaining systemic metabolic and vascular balance. Hepatic failure can lead to serious complications in other organ systems. Hepatopulmonary syndrome, hepatorenal syndrome, and cirrhotic cardiomyopathy–hyperdynamic circulation syndrome are among these complications. Hepatopulmonary syndrome is characterized by pulmonary vasodilation and impaired gas exchange, arising as a consequence of portal hypertension. Increased levels of nitric oxide and prostaglandins lead to arterial hypoxemia, and pulmonary vascular dilatation, anatomical shunts, and ventilation–perfusion mismatches play important roles in the development of the syndrome. Hepatorenal syndrome is defined as functional and reversible renal failure that develops secondary to hepatic failure. As renal perfusion decreases, the renin–angiotensin–aldosterone system becomes activated and the glomerular filtration rate falls. This process results in increased renal vasoconstriction and decreased renal blood flow, ultimately leading to progressive renal failure. Cirrhotic cardiomyopathy is characterized by increased cardiac output due to impaired myocardial contractility, β-adrenergic receptor dysfunction, and systemic vasodilation. Cardiac dysfunctions that develop in chronic liver disease lead to reduced exercise tolerance and hemodynamic instability. Although there are some studies in the veterinary field demonstrating hepatorenal syndrome, more research is needed to determine the prevalence and prognosis of hepatopulmonary syndrome and cirrhotic cardiomyopathy. We believe that a better understanding of liver failure–related syndromes in dogs will contribute to the development of earlier diagnostic and treatment options.