Species differences of fatty liver diseases: comparisons between human and feline

Nonalcoholic fatty liver disease (NAFLD) has emerged as the most widespread chronic liver disease that poses significant threats to public health due to changes in dietary habits and lifestyle patterns. The transition from simple steatosis to nonalcoholic steatohepatitis (NASH) markedly increases the risk of developing cirrhosis, hepatocellular carcinoma, and liver failure in patients. However, there is only one Food and Drug Administration-approved therapeutic drug in the world, and the clinical demand is huge. There is significant clinical heterogeneity among patients with NAFLD, and it is challenging to fully understand human NAFLD using only a single animal model. Interestingly, felines, like humans, are particularly prone to spontaneous fatty liver disease. This review summarized and compared the etiology, clinical features, pathological characteristics, and molecular pathogenesis between human fatty liver and feline hepatic lipidosis (FHL). We analyzed the key similarities and differences between those two species, aiming to provide theoretical foundations for developing effective strategies for the treatment of NAFLD in clinics.