Animal-assisted therapies (AAT) are becoming increasingly common to help hospitalized patients, especially in oncology units. There is a critical need for methods and technologies that can enable a quantifiable understanding of AAT to objectively demonstrate its efficacy and improve its efficiency. In this paper, we present our preliminary efforts towards the development of wireless sensor systems to simultaneously detect the related behavioral (activity level, movement, stroking) and physiological signals (heart rate/variability) of humans and animals during their interaction. To detect heart rate, we tested two different techniques based on wearable or contactless electrocardiography. In this preliminary evaluation, we were able to assess these parameters successfully and identify the design challenges towards deployment of these systems in larger clinical studies.