Diagnostic imaging, including X-rays, MRIs, and CT scans, has long been a crucial tool in monitoring human and animal health. However, for researchers studying wild populations, administering these common tests can be challenging.
In an effort to overcome this obstacle, a collaborative project has been initiated by scientists at the Woods Hole Oceanographic Institution (WHOI) and colleagues at the Cincinnati Zoo & Botanical Garden, as well as other zoos and aquariums. The team is currently testing the use of thermal video and image analysis to measure heart and respiration rates in a variety of animals in a controlled environment.
The ultimate goal of this research is to advance the development of non-invasive techniques for assessing the health of animals in the wild, particularly threatened and endangered species for which more invasive diagnostic procedures might carry prohibitive risks.
A new paper detailing the team’s work was published today in the journal BMC Biology. The study highlights the importance of understanding an animal’s metabolic rate, or energetic expenditure, as it provides crucial insight into a species’ reproductive and survival chances.
Unfortunately, collecting these benchmark measurements from wild populations is logistically complex and frequently invasive. Even more straightforward tests, such as obtaining heart and respiration rates, often necessitate immobilizing the animal, which can pose its own risks. Additionally, attaching tracking devices can be both expensive and invasive.
The research, led by MIT-WHOI graduate student Caroline Rzucidlo, is investigating the potential of infrared thermography (IRT) combined with Eulerian video magnification (EVM) software to measure the vital rates of exotic wildlife species.
Eventually, the team wants to apply this technique to study Weddell seal populations in Antarctica, assessing whether these animals will be physiologically prepared to survive and reproduce in rapidly changing environments.
“Heart and respiration rates are often used as proxies for determining metabolic rate,” explained Rzucidlo. “Thermal cameras can detect changes in skin temperature associated with blood flow and changes in air temperature associated with exhalation. Thus, determining if thermal cameras could non-invasively capture these temperature changes in animals was the first step.”
While thermal video cameras can easily measure heat and body temperature, as evidenced by the technology used to screen humans for fever at airports, the question remained whether this approach could be applied to exotic animals. Taking their work directly into the field was not feasible, as the researchers first needed to validate the accuracy and precision of the method, which required a controlled setting.
“We had no idea how effectively we could measure temperature fluctuations with the thermal camera, including how close or far away from the animal we needed to be, and how fur, fat, or scale thickness would affect the readings,” explained Rzucidlo.
The Cincinnati Zoo & Botanical Garden offered the perfect setting for testing various animals under diverse conditions, allowing researchers to refine their methods. Collaborating with Erin Curry, a reproductive physiologist, and other animal care specialists, Rzucidlo dedicated months to collecting thermal video data on an array of terrestrial and marine creatures at the facility.
The study also encompassed work conducted at other locations, such as the Louisville Zoo (Kentucky), Columbus Zoo and Aquarium (Ohio), and the Salisbury Zoo (Maryland). Overall, 58 individual animals, ranging from Komodo dragons to polar bears, participated in the research.
“Being able to monitor individual animals under human care created a controlled setting to validate this technology that is impossible to replicate in the wild,” said Rzucidlo.
“Zoos offer a unique setting to develop technologies that can contribute to the conservation of wildlife populations. Animals in zoos have regular veterinary check-ups and some individuals are even trained to participate voluntarily in wellness exams, so using a stethoscope to obtain true heartrates while concurrently collecting infrared video of a variety of species was a very achievable goal,” added Curry.
It soon became obvious to the team that the thermal video alone wasn’t enough. “Capturing heat and temperature is one step, but we needed the EVM computer software to amplify changes in temperature associated with respiration rate and heartbeat,” explained Rzucidlo. “Using the two together was the winning combination and offered us an unprecedented view of animal health.”
While thermal cameras have previously been employed to obtain vital rates in a select few species (primarily hairless ones), this groundbreaking study represents the first application of this technology to an extensive array of exotic animals. Additionally, the research identifies the specific traits that render a species suitable for acquiring measurements through thermal imaging.
“This new study takes thermal imaging data in a controlled setting and allows us to build benchmarks across a suite of species. Having developed and fine-tuned these methods in the zoological setting, we can then take these imaging techniques and apply it to answer much broader ecological questions in the wild,” said Michelle Shero, an associate scientist at WHOI.
“We’ve even been using this method in Antarctica to study energy dynamics in Weddell seal populations. We can use these newly developed methods to start asking how an animal’s energetic expenditure may change if environmental conditions change, or what the energetic demands are for reproduction.”
“What’s more, is that using non-invasive and quickly acquired imagery tools will allow us to make better measurements with less disturbance, and for a lot more animals than would ever have been possible using traditional techniques. This is what is really needed to start asking questions about population health.”
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