In preclinical research, animal welfare is a major foundation for relevant and high-quality data. Due to limited technology features in biomedical research, animal welfare can be impaired leading to poor-quality and irrelevant scientific data. Therefore, there is a growing interest in developing new technologies that are able to deliver satisfactory outcomes for both ethical and scientific needs in widely used species in biomedical research such as rats. A telemetric system was developed to meet these needs in the cardiorespiratory field in small animals within 180 grams-3 kilograms weight range. This system called DECRO is a non-invasive connected jacket designed to simultaneously monitor cardiac and respiratory functions, and activity while animals are unrestrained in their environment. This publication describes recommended procedure to achieve proper recording in rats using this jacket.