The Center for Alternatives to Animal Testing is an academic center affiliated with the Division of Toxicological Sciences in the Department of Environmental Health Sciences of the Johns Hopkins University Bloomberg School of Public Health.

Research Grants 2004-2005

Measures to Reduce Stress Caused by Experimental Procedures

Bert van Zutphen, PhD, Vera Baumans, DVM, PhD, Margot Meijer, MSc
University of Utrecht, Utrecht, The Netherlands

Animals that are used in biomedical research are often subjected to routine experimental procedures such as injections or withdrawal of blood samples. These procedures may cause an imbalance of the animal's homeostasis ('stress'). Stress can have an effect on the well-being of the animals and is likely to influence study results, leading to less reliable results and an increase the number of animals needed. The aim of the present project is to measure the animal's stress response to experimental procedures and to investigate the options for refinement. It is hypothesized that the stress response not only depends on the experimental procedure per se but also on the animal's environment (e.g. social vs. individual housing; sawdust bedding vs. cage enrichment).

In this project, the impact of injection techniques in mice is studied. Parameters for measuring the stress response include heart rate, body temperature, body weight, behavior and corticosteroids. Radio-telemetry is used for stress-free collection of data on heart rate and body temperature.

In the first experiment performed in this project, we investigated the influence of cage enrichment, handling and social housing. The results of this experiment showed that individual housing may increase the stress response after injections, based on the slower recovery of tachycardia. Mice are social living animals and individual housing should therefore not be recommended. However, individual housing cannot always be avoided in experimental situations, and therefore we will now focus on the possibilities to reduce the stress response in individually housed mice. What will be the effect of cage enrichment in these animals? Would an increase in the predictability of the procedures by means of conditioning have a positive effect? Can the stress response be reduced when the experimental procedure is followed by a reward? Besides these questions, we will compare different injection techniques as to the degree of discomfort provoked by each of the techniques.