The influence of environmental enrichment on the statement “happy animals make good science”

Abstract

It has been argued that scientists are obligated to do everything practicable to ensure the happiness of laboratory animals, because the reduction of distress experienced by the laboratory animals does not only result in a better animal welfare, but also in good science (Poole, 1997). Poole (1997) also mentioned that “a factor, which is increasingly being recognized as a source of unhappiness, is the failure of the captive environment to meet the animal's behavioural needs and assure its psychological wellbeing. It is becoming apparent that captive animals can be bored or resort to abnormal behaviour if their environment is not sufficiently complex and interesting to them.” A possible solution to this source of unhappiness is the application of environmental enrichment. The provision of environmental enrichment potentially results in ‘happy’ animals which tend to have a normal physiology and express normal behaviour. Therefore, these animals are considered to be good subjects for scientific research (Poole, 1997). ‘Unhappy’ animals, on the other hand, live in distressing conditions (i.e. standard laboratory cages with no environmental enrichment), and tend to have behavioural and physiological disabilities, making them unsuitable subjects for scientific studies. These findings suggest that scientists should provide environmental enrichment to ensure the happiness of laboratory animals if the quality of their research is to be beyond reproach (Poole, 1997). However, concern has been raised that introducing environmental enrichment into the standardized cages of laboratory animals may increase the variability, resulting in an increase in the number of animals needed in order to achieve appropriate statistical power and an increase in the difficulty of duplicating the study in another laboratory (Bayne, 2005; Tsai et al., 2002; Richter et al., 2009). Thus, although it has been agreed that environmental enrichment has a beneficial effect on animal welfare (i.e. introducing refinement), it remains questionable whether the provision of environmental enrichment results in good science. Ultimately, the decision to include environmental enrichment should be based on the consideration whether the enrichment has a beneficial effect on the animal, and whether the potential effects of the enrichment are experimentally relevant (Bayne, 2005). Therefore, this thesis will discuss the influence of environmental enrichment on the statement of Poole (1997), “happy animals make good science”.