There is the issue of what persons are on the lifeboat. If Regan is suggesting that five innocents (human or animal) are on the lifeboat (I don’t think he is) then his position may hold. My gut feeling is that in the event of four innocent children and one dog, I think the dog goes- it is morally regrettable, but might be necessary. And, instinctually I may save my pet (but possibly not a pet) before I save an unfamiliar person. I see how this might be problematic, and even disagreeable. I responded to this entry.
Here is a link to a (2007) essay by Kemmerer that builds on her intial essay in 2005.http://cla.calpoly.edu/bts/issue_07/07kemmerer_1.htm