Guidance

Handling and restraint: General principles

Guidance on best practices in handling and restraint for mice, rats and other laboratory rodents.

Introduction

Laboratory animals are inevitably subjected to human contact throughout their lives, during both husbandry and experiments. The use of appropriate and skilled handling is essential to ensure that animals readily accept or actively seek human contact and procedures are carried out efficiently. If routine handling procedures are aversive, animals are likely to develop anxiety and show exaggerated stress responses when approached. This is detrimental to animal welfare and will increase the difficulty of handling as animals attempt to avoid contact/restraint and may show defensive aggression. Handling stress can also be a major confounding variable and an unwanted source of variation within and between experiments. Good training in non-aversive handling has benefits for the animal, for the handler and for the reliability of data gained in experiments.

General considerations

Approach

Animals should be approached in a calm and confident manner, avoiding exaggerated or sudden movements, such as waving of the hands and arms. Using soft tones and a quiet voice when talking to animals may help alert them to a non-threatening approach and reinforce a caring attitude in the handler.

Handling method

Choice of an appropriate method to pick up, carry and/or restrain an animal is perhaps the most crucial aspect of handling. The method needs to be suited to the particular species (see specific recommendations below); any strain or individual differences also need to be taken into account. More anxious strains/individuals may be much slower to habituate to some methods, requiring further training and/or adjustment of handling techniques, until they are calm and have learned that handling is not a threat.

Restraint

Correct positioning of both the handler and animal is necessary to achieve quick and secure restraint. Animals need to feel secure and to be completely immobile to avoid struggling, which would promote anxiety and could result in injury to the animal or handler. During restraint, the animal should be gripped with just sufficient force to hold it firmly and securely, but not so tightly that it causes discomfort, compromises the animal’s breathing or causes bruising.

Observing the animal's response

It is important to observe the animal’s behaviour during handling as this allows immediate adjustment to keep the animal secure and safe. However, observing the animal’s response on approach and after the animal has been released back into its home environment also provides invaluable information. Anxious animals will often flee from the handler on release and try to evade recapture or, less obviously, they may attempt to hide quietly to avoid attention. By contrast, animals with a positive response to handling are generally curious and will voluntarily approach the handler to investigate and interact. To check the effectiveness of your own handling procedures, try standing motionless for a short period after handling to assess whether animals approach and seek contact [1].

Training and experience: handlers and animals

Acquiring good handling skills needs training in appropriate methods (see below) and much practice to be able to handle quickly and effectively regardless of the specific presentation of the animal, its behaviour and context. Skill should be sufficient to capture animals quickly, confidently and securely on first approach without any chasing. Failed attempts to catch an animal can increase its anxiety and lead to further evasive response, resulting in frustration and sometimes impatience in the handler. Non-aversive handling from a young age during routine husbandry is a fast and effective way to tame animals. The use of non-aversive methods promotes rapid habituation, which is particularly relevant when time is constrained.

Reward training

Where possible, the handler should try to gain voluntary cooperation from animals to minimise any negative response to handling. Reward training methods (also known as positive reinforcement), usually using food treats, work very effectively in dogs and non-human primates and can remove the need for restraint during procedures that animals would normally avoid. For further information see the NC3Rs page on training animals [2, 3, 4].

Handling and restraint of mice

Mice are by far the most commonly used vertebrates in research. Despite this, people find it harder to relate to mice than to more familiar companion animals and mouse behaviours can be harder to recognise and to understand. Their small size makes them vulnerable to predation or other harm, so it is not surprising that mice often show strong handling stress and anxiety in response to capture. Nonetheless, mice adapt readily to human contact if handled appropriately and will voluntarily seek contact, driven by their inquisitive nature.

Mice should be picked up using refined methods, such as a tunnel or cupped hands. Research has shown that picking up mice by the tail induces aversion and high anxiety and generally should be avoided [1, 5]. Although this method was used widely in the past, we now know that it stimulates an inherent anxiety to being captured, to which mice do not readily habituate.

For further information on using refined methods to pick up mice, see our pages on mouse handling.

Restraint

Mice accustomed to being picked up using refined methods will accept physical restraint without losing tameness towards the handler. While mice should not be picked up by the tail, the base of the tail can be held to manipulate the mouse once on the hand. For full restraint, place mice on a surface they can grip. Holding the tail base securely, pull back gently to stimulate the animal to grip and use the other hand to grasp the loose skin at the back of the neck between thumb and forefingers. It is also possible to restrain mice without using tail restraint, by following the approach outlined in Davies et al. (2022) [6]:

"The mouse is placed onto the forearm and then completely covered gently with the other hand. When its head pokes out between the thumb and forefinger the animal is restrained by pinching the loose skin along the back of the animal between the thumb and forefingers in a similar way to a conventional tail handled restraint."

Whatever approach is taken to restrain mice, the animal should be immobilised but able to breathe easily.

Further information on restraint of mice for specific procedures can be found on the Procedures With Care website.

Rats and other laboratory rodents

The principles that apply to mice generally apply to rats and other laboratory rodents, but species-specific differences in behaviour and size alter the specifics of handling procedures that work well in each species. Picking up rats by the tail is stressful and should be avoided [7]. The same is likely to be true of other rodent species. Picking rodents up by the tail increases the risk of degloving injuries (where the skin of the tail is pulled away from the underlining tissue).

For smaller rodents, handling tunnels can be used to transfer animals between cages, and also to habituate animals to being picked up from the cage. Rats habituated to handling can normally be picked up easily by grasping them around the shoulders.

Tickling is one method that can be used to habituate rats to handling – for more information and resources, visit our rat tickling pages. For details of methods of restraint for specific procedures, see the Procedures With Care website.

Other species and additional resources

Mice and rats

The 3Hs Initiative - Resource page on the housing, handling and habituation of laboratory mice and rats
Handling and training of mice and rats for low stress procedures an NC3Rs webinar with Research Institutes of Sweden (RISE)
Norecopa - a refined technique for scruffing mice
Mouse handling pages - how to pick up mice using refined methods
Rat tickling for habituation of laboratory rats to human handling

Rabbits

The following videos show the traditional techniques for how to lift a rabbit and how to restrain a rabbit. Note that the while the scruff of the neck may be used to secure a rabbit, they should not be lifted by the scruff and should always have their weight fully supported from below.

The handling and restraint of rabbits should be refined using positive reinforcement training. For example, rabbits can be trained to hop directly from their enclosure into a transport box, removing the need for capture and manual restraint in some circumstances.

Non-human primates

Amphibia

RSPCA - Housing and care in aquatic species

Fish

References

Hurst JL and West RS (2010). Taming anxiety in laboratory mice. Nature Methods 7: 825–826.
Prescott MJ et al. (2005). Training laboratory-housed non-human primates, Part 2: Resources for developing and implementing training programmes. Animal Technology and Welfare 16:133–148.
Prescott MJ et al. (2004). Refining dog husbandry and care: Eighth report of the BVA(AWF)/FRAME/RSPCA/UFAW Joint Working Group on Refinement. Laboratory Animals 38 (S1): 1-94.
Hubrecht R and Kirkwood J (Eds) (2010). UFAW Handbook on the Care and Management of Laboratory and other Research Animals, 8^th Edition, Wiley-Blackwell.
Gouveia K and Hurst JL (2013). Reducing mouse anxiety during handling. PLOS ONE 8(6): e66401.
Davies, JR et al. (2022). Impact of refinements to handling and restraint methods in mice. Animals 12(17), 2173. doi: 10.3390/ani12172173
Deacon RMJ (2006). Housing, husbandry and handling of rodents for behavioural experiments. Nature Protocols 1: 936–946.

Page contributors: Kelly Gouveia, John Waters and Jane L Hurst, University of Liverpool.

The 3Hs Initiative - Housing, Handling and Habituation

Using refined handling methods and positive reinforcement techniques reduces the distress experienced by the animal and the handler. Both rats and mice can form positive associations with human handling if provided with the opportunity.