Problems that may preclude the use of pigs for influenza studies include caging, the complexities of animal husbandry and waste management. Thus, the recent development of a model in Ellegaard Göttingen minipigs appears to offer an alternative, if these animals can be shown to develop a fulminant pneumonia using a less intrusive route than intratracheal inoculation. However, as in the case of common pigs, minipigs were not susceptible to infection with H5N1 strains such as A/chicken/Yamaguchi/7/04 (Isoda et al., 2006). As with normal pigs one must always be cautious to obtain animals with no previous exposure to influenza viruses, since minipigs can be hosts for swine influenza A viruses (Hansen et al., 1997).