It is important that handling and restraint be conducted in a manner that will cause minimal stress to the animal while preventing injury to the handler. Minimizing stress is important from a scientific standpoint, as well as from an animal welfare perspective (fear and stress responses can result in physiological changes that may contribute to data variability and the number of animals needed to achieve statistically significant results).

For the great majority of species, there will be more and less optimal ways to handle them. To ensure use of the most suitable method, assistance and training should be sought from animal care staff. All animals should be approached in a calm, quiet and confident manner. Developing confidence will, invariably, take an inexperienced handler time and practice.

Animals should be handled regularly to accustom them to human contact and allow for regular clinical examinations. The earlier in the animal's life this process of socialization and habituation can begin, the greater effect it will have, making future handling and restraint less stressful for the animal and easier for the handler. However, handlers should note that the behaviour of animals may vary under different circumstances, for example:

  • a mother with a litter may act in a protective manner when she perceives her young are threatened
  • a sick animal may resent being handler
  • a singly-housed animal may react in a more fearful or aggressive manner compared to those housed in groups

It is necessary to restrain most animals for even the simplest of procedures (e.g., to take the animal's temperature). Physical or mechanical restraint should be used when short-term chemical restraint (e.g., anesthetic, tranquillizer) is not possible, is not compatible with the experimental requirements, or will cause a greater degree of stress for the animal. If restraint is necessary to control an animal during a scientific procedure, then the method used should provide the least restraint required to allow the procedure to be performed properly. Positive reinforcement (e.g., the provision of a food reward, or praise in the case of dogs, cats and primates) should be considered; in many cases, this will help to ease the process when it is next performed.

Two factors that have a strong influence on the degree of stress experienced by a restrained animal are the isolation from conspecifics (during restraint), and the degree of immobilization. Visual, auditory and olfactory contact with conspecifics may help to reduce stress levels. For example, sheep should not be out of sight and sound of other sheep when in an isolation pen.

The quality of the restraint will also influence the animal's response. For example, an experienced handler picking up a rat disturbs the animal less than an inexperienced handler who is afraid of being bitten. Animals become accustomed to repeated, gentle, short-term restraint which is not accompanied by stressful or painful procedures. Longer-term restraint is accompanied by evidence of stress unless the animal has undergone a prolonged period of acclimatization to the experimental situation, and is not subjected to any painful procedures while it is being restrained.

Special Considerations for Handling Fish

Nearly all fish held in the laboratory have to be physically handled. Handling and disturbance appear to be stressful events for fish; therefore, they should be handled only when necessary, and the number of handling episodes should be minimized. Personnel involved in handling fish should undergo training in appropriate methods to ensure their expertise and minimize injury and morbidity to fish in their care. Some key points to consider include:

  • fish should be fasted prior to handling
  • fish should be handled in a fashion that minimizes damage to their mucus-skin barrier
  • restraint and handling of fish should be carried out in a manner to minimize visual stimulation - fish should be protected from direct light and rapid changes in lighting while being restrained

In general, fish should not be kept in air continuously for more than 30 seconds.

This section was adapted from CCAC guidelines and the National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs) website.

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