I would appreciate comments on the following question; feel free to email me (firstname.lastname@example.org) or, I suppose, tweet at me at @AsherLSteinberg if you don't care to comment here. The question is whether states have a compelling interest in protecting the lives of species which they sincerely and strongly believe, for whatever non-religious reason they may have and which may merely sound in sentiment and tradition, it is morally wrong to kill. Does the answer turn for you on whether the state has some reasoned argument for particularly caring about a species, of the sort some animal-rights advocates make about certain species of apes, or is the answer just the same where the reasons for protecting the species are sentimental and traditional, as seems to be the case of dogs?
If you need examples of where this question could matter, it could come up in the case of properly tailored (i.e., not like the law in Stevens), non-content-neutral laws that prohibit the sale of films of a particularly sacrosanct species (dog, chimpanzee) being killed. It could also come up in the case of laws that specifically target religious animal sacrifice, and hence are subject to strict scrutiny Employment Division v. Smith notwithstanding, and could more easily have come up in the pre-Employment Division era (or the post-Employment Division era towards which we may be headed), when religions that practiced animal sacrifice could have challenged generally applicable and neutral laws that protected certain species from slaughter. Suppose, in short, Employment Division is overruled, that religionists can bring Free Exercise challenges, decided under strict scrutiny, to generally applicable laws that burden religious exercise, and that members of a dog-sacrificing religion bring such a challenge to a law that neutrally and generally forbids the non-euthanasic killing of dogs. Who wins?
The question also has relevance (which is why I ask it) in debates about abortion. See, e.g., Jed Rubenfeld, On the Legal Status of the Proposition That "Life Begins at Conception", 43 Stan. L. Rev. 559, 609–10 (1991) (responding to John Hart Ely's criticism of Roe that states are not limited to protecting human life and may also protect animal life by arguing that, in fact, protecting the lives of "ants (or for that matter, stray dogs)" is not a compelling state interest); Sherry F. Colb and Michael C. Dorf, Beating Hearts: Abortion and Animal Rights (attempting, on the basis of an argument from sentience, to square animal-rights theory with a defense of Roe).