This is an interesting topic. Personally, I wouldn't feed my snakes a cat or dog nor would I eat them myself, yet in other parts of the world they are considered a food source. In fact, in many other cultures insects are seen as a food source and are actually considered nutritionally better for you then mammals.
As far as intelligence goes, if we equate intelligence to being more worthy of living then by that same train of thought, dolphins and several other mammals should be worth more than humans as it has been shown that these animals are at least, if not more, intelligent than homo sapiens. Rats are supposedly just as intelligent as dogs.
Should we use cats and dogs as food for reptiles? Well.. it would sure decrease the number of animals being killed at the pounds! Why not just give these animals to zoos or whatever to feed to the larger carnivores? I doubt a lion or tiger or bear would think twice about eating a dog and I'm sure if people knew their family pet would be eaten it might make them stop and think before they so carelessly toss their pets aside when it suits them. :P
Annie B. <:3 )~~