Exemplary embodiments are directed to sensor apparatuses for attachment to an animal that include a housing and a sensor assembly. The housing can be attachable to the animal and includes an internal cavity formed therein. The sensor assembly can be disposed within the internal cavity of the housing. The sensor assembly includes a force sensor and an accelerometer arranged to detect force data and accelerometer data representative of a physiological state of the animal. Exemplary embodiments are also directed to method and sensor systems for detecting a physiological state of an animal.