The 3Rs are Replacement, Reduction and Refinement

The 3Rs are important methods in laboratory animal research for the Replacement, Reduction and Refinement of animal experiments. Researchers are obliged to take the 3Rs into account at the start of an experimental set-up, by using other approaches which do not involve the use of animals, fewer animals, or which entail less painful procedures. The 3Rs have been described for the first time in 1959 by the British duo W.M.S. Russell and R.L. Burch.

Dutch Act on Animal Experimentation (‘Wet op de dierproeven’ in Dutch)
According to the Dutch Act on Animal Experimentation (based on the European Directive 2010/63/EU), no experiments should be conducted on animals, unless there are no other scientific methods available that would produce the required result without using live animals.

The definition of an animal experiment or procedure, as stated by law, is:
 “Any use of an animal for experimentation or other scientific or educational purposes, which may cause the animal a level of pain, suffering, distress or lasting harm, equivalent to the introduction of a needle in accordance with good veterinary practice”. 

More information about legislation and regulations of animal experiments can be found at the Animal Welfare Body of Utrecht University.

Examples of 3Rs in practice

Plastic rat models are useful in Laboratory Animal Science courses

Examples of the incorporation of 3Rs methods in practice:

  • Replacement: eventually, this is the desired aim for scientific methods in which the animal experiments are effectively replaced by animal-free methods. For example computer models or in vitro methods involving cells- and tissue cultures. For educational purposes, plastic rat models are useful in rat anatomy, or bicycle inner tubes are used by students to practice suturing.
  • Reduction: the number of animals for every experimental procedure has to be reduced as much as possible. The researcher has to set up an experiment in a proper and robust manner; by properly utilizing statistical methods to obtain significant results with as few animals as possible, by choosing the right experimental model and by smart breeding techniques to ensure that as few 'surplus' animals as possible are bred. Experimenters can also use modern laboratory instruments like MRI-scans, to follow tumor growth stadia of one animal instead of using more animals. Body parts and organs of one animal could also be used in separate experiments.
  • Refinement: another very important method for responsibly dealing with experiments on animals is to alleviate the pain or stress that they can experience, before, during and after the experiments, to minimize the possible harm to their welfare. Optimal housing conditions, behavioural monitoring and applying anesthetics or analgesics when necessary are important to take into account, as well as humane endpoints. Humane endpoints are the earliest indicator in an animal experiment of (potential) pain and/or distress that can be used to avoid or limit pain and/or distress by taking proper actions, such as humane killing or terminating the experimental procedure. The ultimate goal is to minimize the pain and distress or any other form of harm to the welfare of the animal.