The flexibility of new age wireless networks and the variety of sensors to measure a high number of variables, lead to new scenarios where anything can be monitored by little electronic devices, thereby building Wireless Sensor Networks (WSN). Thanks to ZigBee, RFID or Wi-Fi networks the precise position of humans or animals as well as some biological parameters can be known in real-time. However, since wireless sensors must be attached to biological tissues and they are highly dispersive, propagation of the electromagnetic waves must be studied to build an efficient and well-working network. In this work, the radio wave propagation produced by ZigBee devices working over ISM 2.4GHz based network is studied through a home-made 3D Ray Launching simulation tool. Furthermore, a simplified dog model is developed for the chosen simulation code, considering not only its morphology but also its dielectric properties. This model is placed inside a home, taking under consideration all the furniture (tables, chairs, mirrors, etc.) and some measurements have been carried out attaching ZigBee based Xbee motes to a real dog. Power distribution, Power delay profile and delay spread graphs are extracted from simulation results concluding in an extensive and accurate wireless radio propagation studio. Finally, a dog monitoring system is presented, it works over the zigbee network and sends information to Android based devices.