Welfare of the minipig with special reference to use in regulatory toxicology studies

This paper reviews the animal welfare challenges associated with the use of minipigs in toxicology testing, and compares these to published knowledge on the other widely used non-rodent species (dogs and non-human primates). Welfare challenges arise from housing and management of populations under laboratory conditions, and from the procedures carried out for product evaluation. Welfare assessment requires a multidisciplinary approach: cardiovascular parameters, adrenocortical hormones and behaviour are well known parameters. However, reliable non-invasive methods to assess welfare and species-specific benchmarks need further development in minipigs. Husbandry of minipigs (housing, diet, and socialisation needs) to promote good welfare is described in the revised Appendix A of the European Convention (ETS 123). This has been supplemented by knowledge of species biology and expert opinion from experienced minipig users. Challenges when using minipigs in toxicity testing have been reviewed in detail. Although deeper location of the peripheral blood vessels makes blood sampling more challenging, samples can be taken with minimal distress when staff members are well trained. Temporary and chronic vascular catheters can also be used for frequent sampling, and are likely to improve the welfare of the animals. Available training courses with a focus on stress free handling and dosing, as well as surgical placement of temporary and chronic vascular catheters, should be utilised to improve welfare during these procedures. Humane endpoints have been described, mainly based on current industry practices, but further scientific investigations are required. From an animal welfare perspective there are no basic restrictions to using minipigs in toxicity testing that are unique to this species. We conclude that it is easier to keep minipigs to a good standard of welfare under laboratory conditions than it is for dogs or non-human primates, since minipigs are not athletic (like dogs) or arboreal (like non-human primates).