Infrared thermography (IRT) is a tool that can be used to estimate temperature remotely by measuring the amount of thermal energy that an animal or object emits. All living organisms emit thermal energy in the form of radiation as a result of normal physiological processes. This radiation is emitted as heat photons, or particles that carry energy. An IRT camera is used to measure the heat photons emitted from the animal and to convert them into electrical impulses, which are then displayed as colored images on a monitor. This visual image graphically maps the animal’s body temperature and is referred to as a thermogram.
A significant advantage to this type of technology is that it measures temperature without needing to be in contact with the object being measured, resulting in a non-invasive way of measuring temperature in animals. This technology has been used in a variety of ways with animals, including detecting the presence of animals for population surveys, as a medical diagnostic tool in combination with other indicators of disease, and for the study of thermoregulation as an aspect of animal anatomy and physiology. Some scientists have also been using it to help assess aspects of animal welfare.
Since animal welfare encompasses the physical, psychological and emotional experience of an animal, it is important to use measures that look at all of those components to understand how an individual animal is faring. The body’s response to certain things, such as stress and positive experiences, can have an impact on temperature. This means that in some cases, changes in the temperature of body parts, such as the eyes, can tell us how an animal is responding to an event. This kind of information is really valuable, as we cannot ask an animal directly how it is feeling. It is hard enough for us to understand how other humans are feeling, imagine how difficult it is to grasp how other species, most of which perceive the world very differently than we do and cannot communicate with us using words, are experiencing the world around them from an emotional standpoint.
Finding new ways to assess the emotional lives of animals is critical to advancing our understanding of animal welfare. It is also incredibly important to develop methods that are non-invasive, thereby not affecting the animals during the process. Infrared thermography is a potential way for us to do just this, and our staff is working on new ways to apply it at the Detroit Zoo. We have begun to investigate the use of IRT to assess emotion in gorillas, and the effect of being handled for veterinary exams, for example, on species like penguins and amphibians. The more tools we have to study animal welfare, the better we can be at ensuring animals are thriving.