The animal kingdom's most famous follower of herd mentality can add another unique distinction to its resume: researchers say sheep can be trained to undergo MR scans without the need for anesthesia.

A research team from the National Research Institute for Agriculture, Food and Environment (INRAE), a public research institute in France, has developed a training protocol adapted to sheep in order to carry out MR scans without the need for restraint or anesthesia.

MR scans are often used for neuroimaging in sheep and other animals. Until now, sheep scans had only been performed under general anesthesia, but in addition to jeopardizing studies of brain activity, anesthesia can lead to stress and other negative side effects.
As soon as the lambs were born in the nursery of the Animal Physiology Facility experimental research unit (UEPAO), located at the INRAE Val de Loire centre in Nouzilly, researchers began a familiarization phase. The objective was to identify which animals were most receptive to being stroked or to having foam objects placed near their heads.

After selecting 10 lambs, an initial training phase took place at the Nouzilly farm, where the team trained the animals to climb a ramp to reach a mock MR scanner and then lie down. The lambs were also taught to place their heads in a mock MR coil.

Once they arrived at the real MR room, the sheep were easily able to reproduce the same behavior, but did have some difficulty remaining perfectly still. It took a few weeks for the animals to get used to the vibrations of the machine and stop moving for a few minutes.

Ultimately, the MR images of their brains were comparable to those obtained from anesthetized sheep, a goal that was initially achieved in six out of the 10 sheep trained at the time of writing, and has since been achieved in nine sheep. The protocol lasted nine months, from the birth of the lambs to the first MR acquisitions.

The success of the protocol is already opening up new avenues for research into animal neuroimaging (e.g. fMRI), since it makes it possible to study brain function in awake animals. A study looking into the activation of certain brain regions in relation to hearing is currently underway, and is the subject of a Ph.D. thesis that relies on this training protocol. This example of voluntary cooperation between trainer and sheep illustrates the animal's ability to learn, and underlines the importance of human-animal relationships in the development of innovative methods.

The study also opens up new possibilities for training other animals to carry out awake MR scans. Such training methods could have numerous other applications, in areas such as shearing or medical training, when the animal learns to collaborate during veterinary care.

Until now, dogs had been the only animal species capable of carrying out this type of protocol.

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