The gut-liver axis in animal diseases: roles, mechanisms, and veterinary clinical applications.

The liver serves as the core organ for metabolism, detoxification, and immune regulation in animals. Its functional homeostasis directly determines the animal's health status and production performance. The gut-liver axis, as a critical inter-organ regulatory network connecting the intestine and the liver, plays a vital role in regulating immune responses, maintaining nutritional metabolism balance, and preventing pathogen invasion. The review systematically elucidates the central role of the gut-liver axis in regulating metabolic homeostasis and immune defense in animals. It comprehensively integrates the structural foundations, regulatory mechanisms, and pathological functions of this axis across ruminants, pigs and poultry. It focuses on disruptions to intestinal barrier integrity and dynamic alterations in the gut microbiota and its metabolites (such as short-chain fatty acids, bile acids, etc.). These alterations directly or indirectly influence hepatic metabolism, immunity, detoxification functions and systemic inflammation, thereby contributing to the pathogenesis of various liver and related metabolic disorders. It provides intervention strategies based on gut-liver axis regulation, such as dietary interventions, probiotics/prebiotics, and microbiota-directed modulation. It also explores the application of artificial intelligence (AI) and big data modeling in monitoring the gut-liver axis with the goal of developing early warning systems. By integrating multi-omics technologies to identify key regulatory factors specific to the gut-liver axis, this work extends beyond the conventional gut-centric, single-organ framework to encompass multi-organ synergistic interactions. This approach provides novel theoretical insights and technical support for the discovery of multi-target bioactive compounds and the advancement of precision disease prevention strategies.