Sheep on Valium Teach Scientists about Anxiety

By Elizabeth Preston | June 14, 2016 2:22 pm

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How do you know when a farm animal is unhappy? Animal welfare researchers wish they had easy ways to measure malaise in pigs, or stress in cows. But those tools are lacking—which is why scientists in Australia studied sheep they’d dosed with Valium.

“Animals are not able to talk to express their emotions,” says Caroline Lee, an animal welfare scientist at CSIRO in New South Wales. “We need to use other ways of understanding how they are feeling.”

One such way is to look for changes in behavior that give away an animal’s mood. For example, when humans are feeling anxious, we pay more attention to things that seem threatening. Scientists call this an “attention bias.” If farm animals do the same thing, then testing how attentive they are to threats could be a simple way to measure how anxious they are.

Lee and her coauthors tested this idea with 60 female Merino sheep. They divided the sheep into three groups. A control group went through the experiment with only their natural level of anxiety. The researchers artificially increased the anxiety of the second group of sheep by injecting them with methyl-chlorophenylpiperazine or mCPP—a drug that “has been reported to induce anxiety in a range of species,” they write. The third group of sheep got a relaxing shot of diazepam, also known as Valium.

For testing, each sheep was led into a walled yard with a food bucket sitting in the middle. A window in one of the walls revealed a dog sitting quietly outside. After 10 seconds, the window was shut so the sheep couldn’t see the dog anymore. Each sheep stayed in the yard for about three minutes while video cameras recorded its behavior.

Every sheep except one froze when it saw the dog. But the scientists were more interested in what happened after the window was shut.

Sheep in the control group spent about 22 seconds staring in the direction of the window after it was closed. Sheep injected with the anxiety-increasing mCPP spent almost 40 seconds like this. But sheep injected with the anti-anxiety drug stared for just 14 seconds, on average, before moving on with their lives. More than half of the diazepam sheep then ate from the bucket. Hardly any control sheep could bring themselves to eat, though–and none of the high-anxiety sheep ate a bite.

The more anxious a sheep felt, the more attention it paid to a perceived threat. In the experiment, that anxiety (or lack of anxiety) was drug-induced. But the researchers say the results could provide a new way to measure the anxiety sheep feel from their everyday experiences.

Testing an animal’s attention bias is quick, and doesn’t require a person to have prior training, Lee says. “So it could potentially be used on a farm as a practical indicator of animal welfare.”

As for the drugged sheep, researchers checked on the animals over the next week and found no long-term effects of their pharmaceutical adventures.


Image: by Karen N. Wood (via Flickr)

Lee C, Verbeek E, Doyle R, & Bateson M (2016). Attention bias to threat indicates anxiety differences in sheep. Biology letters, 12 (6) PMID: 27277950

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  • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

    How do you know when a farm animal is unhappy?” It won’t step into the waders with you. Look – yer gonna steal its milk, steal its young, or slaughter it for food. It will be standing in its own excrement being fed the cheapest whatever you can bulk obtain while jammed elbow to tea kettle with its equally angry or forlorn conspecifics. There is no joy for living in the Bronx or being drugged into Progressivism. Their lot is to provide me with happiness.

    pharmaceutical adventures” Youtube v=wLC-y3r66Ys You can escape, but you cannot escape your escape, Youtube v=etYHWZyRSMU Be your own cause, shoot back, and snarl at the Devil Herself, Youtube v=xd_J4ffqc3M. Luminous being are we.

  • polistra24

    Potentially used on a farm????? Come on. This is a pure waste of money. People who work with animals know how their animals are feeling without any gadgets or tests.

    • colbey

      i agree–in a general sense. but that’s likely not true for CAFOs. (which get defined as “farms” by the government and corporations.) that’s where this might have some use–but it would never be used at them for any sort of animal welfare goal. they might possibly “use” it as a way to lie to the public again.

      more likely–the purpose of the study was for animal researchers. they often need to know the mental/emotional state/well-being of their test subjects. not because they actually care about the animals but because…science, you know.

  • Erik Bosma

    Perhaps they should do a study on CGS (Carnivore Guilt Syndrome). Then we can all do Benzos together. We can call it Animal Farm 2.

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Inkfish

Like the wily and many-armed cephalopod, Inkfish reaches into the far corners of science news and brings you back surprises (and the occasional sea creature). The ink is virtual but the research is real.

About Elizabeth Preston

Elizabeth Preston is a science writer whose articles have appeared in publications including Slate, Nautilus, and National Geographic. She's also the former editor of the children's science magazine Muse, where she still writes in the voice of a know-it-all bovine. She lives in Massachusetts. Read more and see her other writing here.

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