Sheep trained to undergo MRI scans while awake

MRI (magnetic resonance imaging) is a commonly used technique to explore the brains of sheep, but until now it was only performed under general anesthesia to ensure the immobility of the animal. This could cause stress and side effects on the one hand, and compromise the study of the functioning of the brain on the other.

An INRAE ​​research team has developed a training protocol adapted to sheep in order to carry out MRI acquisitions in an alert state and without restraint. To do this, the researchers drew inspiration from previous work in dogs, which, until now, was the only animal species capable of successfully completing this type of protocol. In the nursery of the PAO experimental unit, located at the INRAE ​​Val de Loire center in Nouzilly, the researchers began a familiarization phase as soon as the lambs were born. The goal ? Identify the animals most receptive to caresses or to the presence of foam objects near their heads.

After the selection of 10 lambs, a first training phase took place in the Nouzilly sheepfold. The researchers taught the animals to climb a ramp to reach a fake MRI machine and then lie down. The lambs were also taught to place their heads in a dummy MRI coil.

Results: Once they arrived in the real MRI room, the sheep reproduced the same behaviors very easily but had difficulty remaining perfectly still. It took a few weeks for the animals to get used to the vibrations of the machine and not move for several minutes. Ultimately, the MRI images of their brains were comparable to those obtained in anesthetized sheep, this goal having first been achieved for 6 of the 10 sheep trained at the time of writing the article, and since then for 9 sheep. The protocol lasted 9 months, between the birth of the lambs and the first MRI acquisitions.

The success of this protocol is already opening up prospects for research in animal neuroimaging (e.g. MRI), since it makes possible the study of brain functioning in alert sheep. A study on the activations of certain regions of the brain linked to hearing is underway and is the subject of the thesis which required this training work. The results of this voluntary cooperation between the trainer and the sheep illustrate the learning capabilities of this animal, also highlighting the importance of the human-animal relationship in the development of innovative methods. The validation of this protocol opens prospects for training other animals in order to be able to carry out MRI examinations in the awake state. The use of training methods also opens up numerous applications, such as in shearing or medical training (during which the animal learns to collaborate during veterinary care).