An ontology is a way of representing a set of concepts and the relationships between these concepts in a specific field. At present, ontologies are reliable and effective tools for processing and analysing a large number of scientific data with a standardized language and the formalization of knowledge into structured oriented graphs. The design of the data (unique identifiers, relationships, interoperability, etc.) and their characterization (relevance, up-to-date and recognised by the scientific community) are considered. The role of these ontologies is becoming increasingly important due to the increasing number of reports collected every day by the scientific community. The AHOL (Animal Health Ontology for Livestock) ontology has been developed by INRAE with the objective to define and organise the characteristics of farmed animal diseases, as no ontology dealing with these data is currently available to the general public. AHOL is now available on the Web and provides data on 105 swine diseases with their symptoms and pathogens. Each of these three elements is classified in a separate tree structure to facilitate the consultation and search for information. Development is underway to facilitate the search for information by including synonyms (for diseases, symptoms) in the search bar. Eventually, the AHOL ontology will also provide the ability to navigate among diseases of different species (pigs, poultry, rabbits, ruminants, horses, fish). It will then be a useful and effective tool for animal health professionals and students, for use in e-learning for example, and can be integrated into the global ontology network already in place, notably ATOL (Animal Trait Ontology for Livestock)