Handling and identification

Catching and handling


A mouse is caught and picked up by the root of the tail with one’s fingers. The mouse must not be hung for long by the tail and it should be placed on a surface as quickly as possible while still holding on to the tail. For examination or transportation, the mouse can be placed on the palm of one’s hand. Another way to pick up the mouse is to hold it by the neck skin with fingers or rubber-tipped forceps.

You may also catch mice for transfer by making a cup with your hands: place hands on both sides of the mouse or mice inside the cage, slide them together under the mouse/mice, and pick them up. Mice that are unused to this procedure may try to escape, in which case it is good to close your hands. This method is not necessarily successful without prior habituation of the mice. However, for mice that are accustomed to the procedure it is a less stressful and recommended way of catching them.

For performing other procedures, the mouse may be placed on a surface which it can grip (e.g. on the lid of the cage, across the metal wires). Holding on to the root of the tail with a slight pull backwards will make the mouse grab onto the surface with its front feet and hold still. If the mouse is calm, it may be directly grabbed on the neck skin right behind the ears. All the loose skin must fit between the thumb and index finger so that the mouse cannot turn its head. The mouse can be picked up and the root of the tail should then be pressed against the palm with the ring finger or little finger of the hand holding it. Now the mouse is in a secure hold, and the other hand is free, for e.g. injections or gavage.

If the mouse is restless or aggressive, it is better to first press your thumb and index finger on its rear end and press it lightly against the surface, and then slide the fingers over the back to behind the ears to get hold of the neck skin.

You must not be afraid to use sufficiently assertive holds – yet not squeezing too much! – and to act quickly but without haste. Otherwise it will be difficult to catch and control the struggling mouse.


Rats can be caught in different ways depending on their state of calmness and how used to being handled they are, as well as the skill and experience of the person handling it. Alternative holds:

  • Grab tightly around the chest so that your thumb is behind the other front leg, while the other leg remains between your index finger and middle finger, and your index finger is under the lower jaw preventing the rat from biting.
  • Grab the rat at the back so that its neck is between your index finger and middle finger, and your thumb, ring finger, and little finger are around the chest behind the front legs.
  • Collect the rat’s loose neck and back skin together in your hand with a firm grip.
  • Grab the rat by the root of the tail and pick it up on your arm or on a surface, after which it may be grabbed in one of the ways described above.

If the rat is not used to being handled or it is otherwise aggressive, there is reason to be careful and to rather catch it at the root of the tail. When necessary, a strongly struggling animal may be wrapped in a cloth. The rat can be picked up by the tail only for a moment, and it is not a recommendable approach for constant use.


Marking and identiffication of the animals

The animals are marked either by notching the ears, tattooing them or with a marker pen on the tail. The scheme is usually different in different laboratory animal centres. Therefore the scheme must be sent alongside with the animals to the associates of the LAC. An ink mark must be intensified almost daily, but the notches and tattoos are permanent.

Last updated: 5.1.2017