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.
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.
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.
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 contact1.
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.
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 animals2-4.
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.
Research has shown that picking up mice by the tail induces aversion and high anxiety and generally should be avoided1,5. Although this method was used widely in the past, it appears to stimulate an inherent anxiety to being captured, to which mice do not readily habituate. Instead, where possible, mice should be picked up by a non-aversive method that promotes a positive response to human contact.
A recommended method to pick up mice is to guide them into a handling tunnel, lift them inside the tunnel and transport them to their destination. Gently tip animals from the tunnel backwards, directly onto the surface or hand (a smooth plastic tunnel that the animals cannot grip is best). Use one hand to hold the tunnel and the other to guide the animal. With good technique, animals can be confined immediately and it takes no longer than other methods. Though contact with the handler is minimal when using a tunnel, mice quickly habituate to handling and readily accept human contact when tipped from the tunnel, even after physical restraint. Although handling tunnels do not have to be present in the home cage to be effective, having a handling tunnel in the home cage increases recognition of a familiar safe site as well as providing cage enrichment. Home tunnels are also particularly useful for more anxious strains5.
Another method is to simply scoop the mouse onto the hand. This works well once mice have become habituated to being picked up, although naïve and more jumpy young animals will initially leap from the hands. To habituate them, animals can be held loosely between closed hands initially (for example, to transfer between cages during cleaning) or picked up in a handling tunnel until they no longer jump from the hand. Observe the animal’s response closely to ensure that it is cupped and transferred safely. This method is suitable for docile strains, animals that are well habituated to handling and stay on the hand, and for experienced handlers with a confident approach. Use of a handling tunnel is recommended for less confident mice and handlers.
Mice accustomed to non-aversive handling 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. 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.
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 avoided6. The same is likely to be true of other rodent species, many of which shed the skin from their tails as an anti-predator response. 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. It is very important to habituate rats to good handling to avoid bites, which can be severe. For details of methods of restraint for specific procedures, see the Procedures With Care website.
- Hurst JL, West RS (2010). Taming anxiety in laboratory mice. Nature Methods 7: 825–826.
- Prescott MJ, Bowell VA, Buchanan-Smith H (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, Morton DB, Anderson D, 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, Kirkwood J (Eds) (2010). UFAW Handbook on the Care and Management of Laboratory and other Research Animals, 8th Edition, Wiley-Blackwell.
- Gouveia K, Hurst JL (2013). Reducing mouse anxiety during handling. PLOS ONE 8(6): e66401.
- Deacon RMJ (2006). Housing, husbandry and handling of rodents for behavioural experiments. Nature Protocols 1: 936–946.
Information provided by Kelly Gouveia, John Waters and Jane L Hurst, University of Liverpool
Last updated: November 2013