Animal models of toxicology testing: the role of pigs.

INTRODUCTION: In regulatory toxicological testing, both a rodent and non-rodent species are required. Historically, dogs and non-human primates (NHP) have been the species of choice of the non-rodent portion of testing. The pig is an appropriate option for these tests based on metabolic pathways utilized in xenobiotic biotransformation. AREAS COVERED: This review focuses on the Phase I and Phase II biotransformation pathways in humans and pigs and highlights the similarities and differences of these models. This is a growing field and references are sparse. Numerous breeds of pigs are discussed along with specific breed differences in these enzymes that are known. While much available data are presented, it is grossly incomplete and sometimes contradictory based on methods used. EXPERT OPINION: There is no ideal species to use in toxicology. The use of dogs and NHP in xenobiotic testing continues to be the norm. Pigs present a viable and perhaps more reliable model of non-rodent testing.