The term refinement signifies the modification of any procedures that operate from the time a laboratory animal is born until its death that minimise the pain and distress experienced by the animal and enhance its well-being.
Being aware of animal welfare is not only important from the viewpoint of ethics, it is also a matter of good science. The experience of pain and other stress is likely to result in physiological changes which may increase the variability of experimental results.
Therefore, it is in the interests of scientists to ensure that conditions in the animal house are the best possible.
The environmental enrichment of laboratory animal housing
This need not be an expensive exercise. Toilet rolls, egg cartons and PVC tubing can provide rats and mice with places in which to hide. Bales of straw and rubber tyres can be used to create an area for rabbits to interact with others of their species. Dogs can be given toys to play with, and be provided with a raised platform so that they are not forced to stand in their own dirt.
The choice of species
Some species have a greater capacity to feel pain and distress, and therefore should only be used when absolutely necessary. Some species have more complex husbandry requirements and should not be used if the institution cannot provide appropriate facilities. Moreover, there are environmental, ethical and scientific arguments for giving preference to captive-bred animals rather than those caught in the wild.
Once the study is in progress, it is important that laboratory staff are well trained and competent in the handling of the species that is being used, and that they have the correct attitude towards the animals. Anaesthesia and analgesia should be used whenever appropriate and possible. The injection volumes used should be as small as possible as should the sizes of needles. The endpoints and measurable parameters used in the experiment should be those which are least invasive and which can be assessed as early as possible, so as to minimise both the distress caused to the animals and the duration of the study. Where possible, researchers should aim to reduce the frequency with which samples are taken and also the volume of each sample.
Using the least invasive methods
In some cases, it may be possible to use a non-invasive method. For example, high-quality MRI (magnetic resonance images) can provide information on the distribution of water and electrolytes, fat deposition and the development of oedema in an organ tissue, MRS (magnetic resonance spectroscopy) can be used for serial non-invasive measurements of xenobiotics, metabolites and endogenous compounds in cells and tissues, and can enable differential measurement of mitochondrial and cytosolic pH. New advances in MRS raise the possibility of it being used in future to investigate more-complex structures, such as receptor interactions and cell membrane perturbations.
At the end of the experiment, the most humane method of euthanasia should be chosen. Guidelines on the killing of laboratory animals are available, which discuss the problems associated with the use of some methods.
More information on refinement can be found by going to the external links or papers listed in the submenu to this page or by searching the paper database.