According to this paper,
ScienceDaily (Feb. 14, 2011) — New research shows that all not mammals are created equal. In fact, this work shows that the animals most commonly used by scientists to study mammalian genetics — mice — develop unusually quickly and may not always be representative of embryonic development in other mammals.
Hmm. Lab rats might not work out either. For medical purposes, the only solution, I guess, is to use lab technicians and postgrad students instead. Some regulations appended to the legislation may need to be changed, of course, but it shouldn’t take too long …