[Transgenic Animals within the 3R concept]

There are positive examples of transgenic animals where transgenic technology has allowed the use of less animals to answer a specific research question. On the other hand, it requires large numbers of animals to produce transgenic strains. And there remains the question, when these animals show clinical signs of disease, if they suffer more or less than their "pretransgenic" counterparts. To what extent transgenic animals further the cause of the 3Rs must be evaluated on an individual basis.