The Three Rs of reduction, refinement and replacement are the cornerstones of attempts to combine good science and effective animal welfare while maintaining the goals, validity, and quality of each (Russell & Burch, 1959). Morton (1999) defines refinement as "[t]hose methods which avoid, alleviate or minimize the potential pain, distress or other adverse effects suffered by the animals involved, or which enhance animal well-being."

It is imperative for good welfare and good science to create conditions where animals do not experience prolonged and inescapable stress and distress. Individuals who care for and use animals in toxicology research need to be cognizant of the behavioral, emotional and physiological states of their subjects, of the animal's potential to anticipate negative events that may subsequently cause/increase anxiety levels, and of the impact that these negative emotional/physiological states may have on the experimental results. An animal's anticipation of upcoming events (e.g., daily or weekly blood withdrawal or injections, or even handling practices) and anxiety in conjunction with states of boredom, frustration, and depression due to husbandry practices, may have a profound effect on the immune responses via the hypothalamic-pituitary-adrenal (HPA) axis, and alter responses to the toxicological substances being tested (Carstens & Moberg, 2000).

The use of humane endpoints in coordination with clearly determined behavioral and clinical criteria (i.e., the point at which the experimental results can be achieved without causing an animal to suffer, pushing it into a moribund state) is another approach to the elimination of pain and distress experienced by animals used in toxicity testing (Morton, 1999). The development of humane endpoints can be approached by the use of appropriate scoring systems, non-invasive monitoring schemes, and environmental enrichment.

The presentations at the workshop all dealt with refinements or best practices and the highlights are briefly summarized below. The first section of the workshop discussed dosing regimens for toxicity studies. Dr. Jon Richmond (U.K. Home Office Inspectorate) outlined their dosing guidelines but indicated that these were under revision. Dr. David Smith presented the draft recommendations of an EFPIA committee on dosing guidelines (ESLAV web site, 2000), which are summarized in "Dosing Data and Volume."