Immunosensors can play an important role in the improvement of veterinary diagnostics in areas such as the diagnosis of diseases, drug detection and food quality control, by providing applications with rapid detection, high sensitivity and specificity. Associated with advances in biochemistry, biotechnology, electronics and microfabrication, new transduction devices that translate a biological interaction into an electrical signal have been developed. An overview of the current immunoassay techniques used in standard diagnosis is presented. This includes a brief description of the different immunosensor transducer principles and some examples of present and future developments.