Did you know that animals can diagnosis diseases?Before a doctor can treat a patient, she needs to know what is causing the problem. However, it is not always easy to tell what kind of sickness is affecting someone. Readers will find out how animals can be put to work diagnosing some of the trickiest diseases, from dogs who sniff out cancer to mice who can detect bird flu. They will also learn how scientists are working to reproduce these animals' abilities with advanced electronic devices.