Animal Science

Subtle changes detected in eye temperature can indicate animal stress

30 May 2020
Subtle changes detected in eye temperature can indicate animal stress

Thermal imaging can detect subtle changes in temperature in a sheep’s eye that help us understand the levels of stress it is feeling, a study by AgResearch scientists suggests.

Research in which the thermal imaging technology is focused on sheep, as a potential tool to help assess and enhance welfare, has been published today in the international PLOS ONE scientific journal. The article can be viewed at: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0233558.

“For some years now at AgResearch we’ve been looking at how infrared thermography (using a thermal imaging device that detects the amount of infrared energy an object radiates) can help us gain a better understanding of the stress levels livestock may be experiencing, and therefore their welfare,” says AgResearch senior scientist Dr Mhairi Sutherland.

“A key advantage of this technology is that it is non-invasive when clearly the aim is not to add to the stress of the animal in the course of trying to take these measures. The technology has also been used to detect the presence of disease or inflammation in animals that may require further investigation.”

“After demonstrating that infrared thermography could be used to detect stress responses in cattle, we undertook similar research in ewes (female sheep) where we focused on temperature changes of the eye region as a measure of stress and activation of the autonomic nervous system. By comparing ewes injected with epinephrine (also known as adrenaline) and those without, we were able to see subtle temperature changes in the eye. We focused on the eye region because it is not obstructed by wool, but we did look at other areas of the body such as the ear, where there may also be the potential to detect changes in temperature that relate to stress.”

“At this stage, infrared thermography to detect stress responses in animals is being used primarily as a research tool, but there is potential for this technology to be integrated into farming systems, where animals may be directed to pass by an infrared thermography checkpoint to take measurements relating to stress or health. Once you have the tools to detect stress responses in animals, you can of course then look at what situations or circumstances are causing the stress for the animals, and how you can adapt farming practices to reduce this and enhance their welfare.”

“Our experience is that farmers want the best for their animals and are open to how to evolve their practices, and we know that good welfare standards are also an important factor for consumers of food and fibre produced in New Zealand."

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