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A flock of merino sheep at UWA’s research farm at Wundowie are helping scientists understand more about a condition that affects millions of people around the world every year. Dr Penny Hawken , from the School of Animal Biology, has recently co-authored a paper in Physiology and Behaviour , in which she suggests that handing out benzodiazepines – commonly used to treat anxiety (which often leads to depression) – may not be beneficial for everyone.

Interested in the increasing use of alternative therapies to treat medical conditions in humans, Dr Hawken studied the effects of lavender oil on a group of anxious sheep and on a group of calm sheep.

While rodents are often used to model health problems in humans, sheep can sometimes be a better model and, at UWA, they have been used for research into pre-term birth in humans and the effects of stress in pregnancy.

Dr Hawken grew up in North Wales and started horse-riding when she was nine. As a teenager she was a volunteer at several animal rescue charities and local farms. In WA since 2005, she noticed that chamomile tea had a calming effect on her own horses and wondered if lavender oil might have a calming effect on nervous sheep.

Lavender oil and other essential oils do have a direct effect on the brain and with more research they could be used as alternative treatments to conventional drugs, she said.

To find out how sheep reacted to lavender, she and her colleagues devised a study.

She explained that UWA had been breeding two lines of sheep for about 18 years to study the effects of temperament on a range of outcomes including lambing and meat production.

“The calm sheep ovulate more, have more lambs and are better mothers, especially in challenging situations,” she said. “They tend to be more concerned about their offspring.

“The nervous sheep are not such good mothers as they are more concerned about individual survival.

“The pathways in the brain that mediate the effects of lavender oil are thought to be similar to those used by benzodiazepines,” she said.

In the study, the calm and the anxious sheep were each put into a big solid plywood box. The sheep were in no physical danger but found the situation stressful as they dislike isolation from the rest of the flock.

The control animals in both groups had a mask of just peanut oil placed over their muzzles while the others had a mix of peanut and lavender oil. The animals were observed for signs of distress (such as pawing, urinating and calling out) and the level of cortisol – the stress hormone – in their blood was measured.

“The lavender oil made the calm sheep even calmer but made the nervous sheep even more nervous,” she said.

“The study suggests that genetic differences in temperament determine whether lavender oil alleviates or exacerbates anxiety in sheep. This result could be extrapolated to people who have divergent behavioural and hormonal responses to the same stressor.”

The paper’s other authors were UWA’s Associate Professor Dominique Blache and Dr Carolina Fiol, a researcher from the Facultad de Veterinaria in Montevideo, Uruguay.

Published in UWA News , 29 October 2012