The number of animals within European dairy herds is increasing and the time for surveillance of each cow decreases. The aim of the present study was to develop an intraruminal device for monitoring changes in conductivity, pressure, and temperature in individual cows. The precision and accuracy of the device was evaluated by in vitro and in vivo experiments. Whereas conductivity was increased by volatile fatty acid anions concentration-dependently, it was reduced by an increase in osmolarity. For changes in temperature, conductivity and pressure, high correlations were observed between values obtained by the intraruminal device and those registered by external reference methods. The intraruminal device might be of benefit to future feed and management systems for dairy cows.