Over at The Ümulaut, it's pointed out that dogs are not very utilitarian, which calls into question the strength of utilitarian analysis:
Utilitarianism is fundamentally about rationalizing human behavior; this is its first goal before arriving at its stated goal....How one understands dog ownership from this perspective is a mystery to me. If you own a dog and take the trouble to keep it alive, healthy, and happy, you have to sacrifice a great deal. There are the simple financial realities of feeding a dog and vet visits and medication or treatment when necessary, and often dog walkers as well. Then there is the sacrificed freedom—it is much harder to be spontaneous after work in terms of going out or seeing people; someone has to make sure to dog goes out, gets fed, and so on. And, for many people, there’s the added anxiety of having a life that depends on you — you invest emotions in your dog in a way that makes you vulnerable.