Given the centrality of pain to most accounts of our ethical obligations towards animals, as well as the importance of animal models of pain in clinical medical research (see Mogil 2009 for a review), it is hardly surprising that there is a substantial (albeit controversial) scientific literature bearing on animal pain. Reports by the Nuffield Council on Bioethics in the U.K. (Nuffield Council 2005; see esp. chapter 4) and the U.S. National Academy of the Sciences Institute for Animal Laboratory Research (ILAR 2009) have recently covered the definition of pain and the physiological, neurological, and behavioral evidence for pain in nonhuman animals. These reviews also distinguish pain from distress and suffering (see also Bermond 2001), and the ILAR has divided what used to be a single report on recognition and alleviation of pain and distress into two separate reports, although the scientific investigation of distress is relatively rudimentary (but see Dawkins 1985; Farah 2008). 