Share thisRecent studies have shown that enrichment improves the results of laboratory experiments, but it can make experiments more expensive and labour intensive. How much enrichment is sufficient?
Every species in the zoological kingdom is endowed with innate behaviour patterns tied to a place in the predator chain, and each creature is impelled by the very force of nature to express those patterns. That is not in dispute. Yet, providing opportunity for experimental animals to express species-specific behaviour remains a dilemma, for several reasons.
Repressing natural behaviour produces anxiety and stress, irrespective of the species, which is a sad and sorry state for the animal and affects the outcome of the experiment. However, until recently, bringing the wild inside the lab has not seemed financially or logistically practical. And, some people who accept the notion of innate behaviour across the fauna—yet believe that only humans are sentient— conclude that the extra expense isn’t necessary.
Also, the specification for an environment that sufficiently allows expression of innate behaviour is not generally agreed, so people who speak about such environments—called enriched environments—often have very different practices in mind. In the field of neuroscience, enrichment provides for an extremely stimulating environment, as the aim is to stimulate the brain as much as possible in order to enhance learning and memory capacities. From the point of animal well-being, enrichment (perhaps here more aptly characterised as refinement) provides for the animal’s species-specific basic needs and opportunity to express them, in order to minimise animal suffering and gain the best possible data. This is consistent with the aim of reduction and refinement in the practice of animal research, and calls for tailoring enrichment to the animal and the research goal. In addition, perhaps thanks to the widely publicised notion of enrichment as palliative for animal welfare activists, in some quarters enrichment has taken on the patina of novelty and fashion, as if enrichment equals anything added to the standard cage.
Considering investigators and research institutions, there is the matter of calculating the trade-off between potential benefits to experimental results of providing for natural behaviour, and the costs in time, energy, and money of doing so. And there is the difficult issue of coping with change—in expectations, perspective, and behaviour. Rife as they are with false starts and growing pains, such changes can be slow-going and difficult for individuals and organisations, and may ruffle feathers among vested interests.
ENRICHMENT AS PREVENTION
A recent, distinguished cancer study brings this problem of change straight to centre stage.
Matthew J. During, Professor of Molecular Medicine and Pathology at the University of Auckland in New Zealand where he directs neuroscience and gene therapy programs, and colleagues demonstrated that in an enriched environment mice are less susceptible to cancer. Specifically he found that an enriched environment caused melanoma and colon cancer remission and inhibition—and also that exercise alone didn’t produce this result. Dr During defines enrichment as complex housing with sensory, cognitive, motor, and social stimulation that offers dynamic social interaction, exposure to novel objects, and enhanced physical activity. He says that such housing influences the interaction between the central nervous, endocrine, and immune systems.