Which is exactly why I think having "pets" is pretty f**ked up when you actually think about it. Obviously, saving cats and dogs from being put down by adopting them should still be encouraged. But if you're going to feed those animals other animals, can that really be justified? Unfortunately, it's too late to "unbreed" domesticated animals so we're stuck with huge dilemmas on how to address these issues.
This is why none of us (well I certainly hope so) here support breeding. It would be inhumane to let carnivorous animals die for the sake of being carnivores. If killing a cat simply to reduce meat consumption is justifiable, then killing a lion to save zebras would also be justifiable.
In the future I'd love to adopt more animals, which includes obligate carnivores like ferrets (ferrets are just so cute *squee*). I'd still be forking over much less money to the meat industry than the average meat eating human.
Another way of looking at this "dilemma" is to ask if the question being posed is based on a valid quandary.
Can we synthesise "meat" from vegetable sources? Yes IMHO, so then why do all of these other animals die needlessly from the misguided beliefs that a vegan diet is inadequate?
And:
Do we really know enough about what a dogs diet really should be? What presumptions are we working on when we assume that all dogs/some dogs are carnivores/omnivores?
Different animals have different digestive systems. We as humans can absorb plant protein perfectly fine, but other animals such as cats absorb animal-sourced protein much more readily. Dogs are much less fussy about protein sources than cats are.
Still, a raw carnivorous diet would still be optimum for a dog's health. But then again, one dog's health wouldn't be worth a hundred other lives. But then again, even if we don't buy meat, we're NOT actually saving any lives. Leftover farm animals get shot if demand is low. What we ARE reducing is the number of animals being bred into existence.