The RETHINK project--minipigs as models for the toxicity testing of new medicines and chemicals: an impact assessment.

The objective of the RETHINK project was to evaluate the potential impact of toxicity testing in the minipig as an alternative approach in regulatory toxicity testing that can contribute to the replacement, refinement and reduction of animal testing (3Rs). Minipigs are strains of domestic pigs that are markedly smaller than farmyard varieties, and thus better adapted to laboratory housing. The pig closely resembles man in many features of its anatomy, physiology, biochemistry and lifestyle. In particular, the cardio-vascular system, skin and digestive tract are considered to be very good models for man. Because of these similarities the toxic effects of chemicals and drugs in pigs may resemble the effects in man more closely than do some other commonly used laboratory animals. The pig also has some features that make it a very practical model for laboratory studies. Finally, being a food animal, testing in the minipig may be more acceptable to the public than animals such as dogs or monkeys. Expert study groups (Working Groups) were assembled to review five different areas relating to the use of minipigs in regulatory safety testing: ethical issues, welfare and animal care, development of new medicines and chemicals, safety testing issues and emerging technologies in safety testing. Their conclusions are presented in the articles of this special issue. The RETHINK project was funded as a Specific Support Action under the European Community 6th Framework Programme.