My wife and I are dog people and our dogs are shelter dogs, usually less-adoptable or non-adoptable misfits my wife has brought home from the shelter.
Dogs and cats ought to be scarce. The "breeding" of dogs, especially types of dogs with known health issues, ought to be severely curtailed.
Dogs started out as wolves. Wolves have a lot of depth to their gene pool and modern dogs were created by a mostly subtractive process -- we killed off or drove off wolves that were incompatible with our human communities and we ended up with dogs. These dogs, with increasingly shallow genetic diversity compared to wolves, were further culled to create the modern dog breeds we know today. It was an ugly process, and it's only recently we can pretend otherwise.
I grew up in a home where the dogs often outnumbered the people and this has often been the case in my life as an adult. And it's the same with my siblings.
We've had dogs who were the surplus of fads -- dalmatians, huskies, etc.
My wife's family tend to be cat people, and their story is similar.
These animals have a large environmental footprint just as people have a large environmental footprint.
If we want to protect what little is left of the earth's natural environment as it once was we need to halt the population growth of humans, our domestic animals, and our pets.
My wife is vegetarian approaching vegan and I'm mostly vegetarian. I'm not sure I can expect the same of our dogs, especially the "ancestral" breeds like huskies that don't really recognize grains as food.
The dogs we live with now would be happy to kill their own food and might be even happier in a family that hunted or butchered livestock. It's been a long time since I've hunted or butchered livestock. Their base diet is kibble I buy at Costco.
Vegetarian dog food is something I'd have to buy from internet sellers. Of all the ways I might reduce our household's environmental footprint I haven't gone there yet.