Animal research has always played a crucial role in various medical and scientific breakthroughs. They offer, inter alia, insights into diseases mechanisms, genetic predisposition to a disease, and drug therapy. However, the use of animals for medical research is a cause of major controversies and debates in modern science. To warrant high bioethical standards, new directives have been being adopted to replace animal research whenever possible, to reduce the number of animals, and to refine the procedures to minimize stress and pain. Here, we present two new approaches, based on thermal imaging (a remote and passive technology), to assess respiratory rate (RR) as well as exploratory behavior and general activity in rodents. In animal research, these parameters are gold standards for welfare assessment. The approaches were validated in a study conducted with both rats and mice. To test the feasibility of our algorithm to estimate RR, thermal videos from anesthetized rodents were acquired. The capability of the second approach to monitor activity was tested with videos of Open Field tests. Regarding RR, a high agreement between thermal imaging and gold standard (electrocardiography-derived RR) was achieved. The mean relative error averaged 0.50 ± 0.15 breaths/min and 4.55 ± 2.94 breaths/min for rats and mice, respectively. The second approach was capable of monitoring and tracking the activity of the rodents very well. This paper demonstrates that thermal imaging is a promising and relevant alternative for monitoring of RR and activity in rodents, thus contributing to the remote assessment of animal welfare.
Keywords: animal research; infrared thermography; locomotor activity; motion heat maps; remote monitoring; respiratory rate; thermal imaging; vital signs.