The disease often suffered by Sugar Glider shown in terms of physical condition. However, the illness is often undetected by Sugar Glider owner until it reaches a serious stage and only began to be noticed after consulting with veterinary doctors. Therefore, this expert system allows the owner of Sugar Glider makes a preliminary diagnosis by selecting its symptoms. Selected symptoms will produce result contain diseases and treatment methods. Development of a knowledge base about the symptoms, diagnosis and treatment method for Expert System Apps for Diagnosing Sugar Glider Diseases (SGApps) have involvement and cooperation from one of the lecturer in Faculty of Veterinary Medicine, University Putra Malaysia. Knowledge engineering model has been chosen as methodology while forward chaining as the inference method. Atom software, the Apache server and MySQL database are implemented to develop a web-based system for the administrator. Next, Bootstrap software is used as a development platform for android, MySQL as database and Visual Studio as a compiler. Usability test by doctor suggests that this expert system can produce suitable diagnosis results that match the input symptoms. While usability testing with the owner of Sugar Glider show this android based expert system can provide information on proper care of the Sugar Glider. Finally, the system can allow users to ask any questions directly to the veterinarians.