This document discusses different types of animal health surveillance systems. It describes passive surveillance as provider-initiated reporting, while active surveillance is health department-initiated. General surveillance collects data on multiple diseases, while targeted surveillance focuses on a specific disease. Data sources can include recorded diagnoses, clinical signs, survey reports, indirect indicators, and risk factors. Common surveillance systems are farmer-based, facility-based, sentinel, syndromic, and surveys. Each system has advantages and limitations for early detection and monitoring of animal diseases.