No-one wants to use animals unnecessarily or to cause them unnecessary suffering. The
guiding principles in animal research today are called the three Rs:
- Reduce the number of animals used to a minimum
- Refine the way experiments are carried out, to make sure
animals suffer as little as possible
- Replace animal experiments with non-animal techniques
wherever possible.
Reduce
There are many ways in which one can reduce the numbers of animals used in an
experiment. It is very important to carry out a proper statistical analysis of the proposed
experiment to determine how many animals need to be used. If too few animals are used
then the results of the experiment are not reliable and it needs to be repeated, using more
animals. Use too many animals and the results are still reliable, but animal life has been
wasted. To reduce the number of animals used to the minimum, the correct number of
animals must be used the first time.
It is also important that all other aspects of the experiment are properly designed and
carried out correctly. If the experiment fails and needs to be repeated, animals will have
been used unnecessarily. Another way of reducing the number of animals used in an
experiment is to use genetically identical animals. This prevents variation in the results from
genetic variations between individual animals and thus makes it possible to get reliable
answers using fewer animals. A reduction in the numbers of animals used can also be
achieved if the animals are born and bred in ultra-clean conditions and are free of any
infections or illnesses which might otherwise interfere with the experimental results.
Refine
Research involving animals has to be designed so that any distress or suffering involved is
kept to a minimum. For example, if the experiment would hurt the animal, an anaesthetic or
painkiller would normally be given. If an experiment involves taking repeated blood
samples from an animal to measure, for example, the level of a particular hormone, it may
be possible to implant a small device to continuously monitor the hormone. This can be
done with a simple operation under anaesthetic, so that the animal does not have to be
repeatedly caught, restrained and blood taken by syringe.
If an experiment involves animals with a painful or fatal disease, it can be designed so that
the animals are painlessly killed at an early stage of the disease, when they only show mild
symptoms, instead of waiting until they are clearly dying.
In some cases it is possible to develop a whole new way of conducting a test involving fewer
animals. The LD50 test has been used for many years to find out how poisonous chemicals
are. The way the test is designed means that some of the animals have to be given a fatal
dose of a poisonous chemical. However, scientists have now developed a new test, called
the Fixed Dose Procedure, to do the same job. This technique uses fewer animals and is
designed so that none of them receive a fatal dose of the poison. The LD50 is now outlawed
in the UK.
Laboratory animals spend most of their lives simply living in the animal house and not being
used in an experiment, so it is important to consider their living conditions. In the past,
laboratory animals would often be kept alone in barren cages. These days we prefer to
keep animals in social groups, preferably in large cages or floor pens, with things for them
to play with. Rabbits would be given bedding material, boxes and tubes. Rodents like to
have nesting material. Dogs like running in groups and having human company. Monkeys
like branches to climb, swings, ropes and platforms. Their diet can also be made much more
interesting with fruit and other titbits. Some of these can be mixed in with wood shavings so
that they have to forage for their food - a favourite activity.
Replace
A lot of scientific effort has been devoted to developing new, non-animal techniques which
can be used in experiments instead of animals. There have been some notable successes,
but overall, progress has been disappointingly slow.
- The LAL test can now be used to test for pyrogens. Bacteria often shed little bits of their
outer covering. If these substances, known as pyrogens, get into the bloodstream, they
raise the body temperature. Even very tiny levels of pyrogens cause a dangerous
temperature rise, so any liquid going to be injected or fed into a patient's blood stream has
to be tested for pyrogen contamination. Previously this was done by injecting the liquid into
a rabbit and monitoring the animal's body temperature. The new LAL test uses white blood
cells taken from the horseshoe crab which can detect the pyrogens in a test-tube.
- Insulin is a lifeline for millions of diabetics, but it is essential they give themselves the
correct dose - either too high or too low a dose can be harmful. Each batch of insulin has to
be tested to measure how active it is so that the correct dosage can be calculated.
Previously, this was done by injecting the insulin into mice. Now that insulin is produced by
bacterial culture rather than being extracted from pig and cow pancreases, it contains fewer
impurities. So a new technique has been developed which uses a machine called a
chromatograph which can provide information about purity, replacing the need to use
animals to test for the purity and activity of batches of insulin.
- Many non-animal techniques have been designed to replace the animal tests used in
safety testing, but these new techniques do not always work well enough. A great amount of
scientific work has been devoted to the search for a non-animal test to replace the Draize
eye irritation test. This test studies whether a chemical irritates the eye by dropping a
dilution of it directly onto the eye of an animal, usually a rabbit. Several different non-
animal tests have been designed and have all been assessed to see if they accurately
predict whether a substance will irritate the eye. Unfortunately, none of them worked well
enough to be used to replace the existing animal test. Work is continuing to find a
replacement for the Draize test.
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