Plant cells are different from animal cells. Plant cell walls are thicker and tougher to open. The carnivore digestive tract is not designed to glean nutrition from plants. The carnivore digestive system is short compared to ours and vegetable matter just goes out the back end without being used.
The human gut is long and designed to ferment plant foods. This fermentation and length of time gives plant cell walls a chance to break down and release the nutrition inside. A good system for omnivores. Our carnivore friends (dogs, cats, and sharks) have a short gut designed to break down raw meat. The cell walls of raw meat are more delicate than plant cells and release their nutrition quickly. Perfect for carnivores.
The carnivore short gut also allows the quick exit of any pathogens that might be on the raw meat so the animal doesn’t get sick. We could also get nutrition from raw animal meat, but that long gut of ours may harbour bad bacteria or intestinal parasites long enough to make us ill. Sushi and steak tar tar are different because the meat is handled very carefully to avoid bacteria and worms.
So, should you feed your dog fruit and vegetables? In short, no. But I realize that some dogs love their veggies and some plant matter isn’t going to be harmful. It just goes out the other end. Your dog will get a little nutrition from the veggies, but they can’t get at the nutrients easily. Dogs and cats aren’t vegetarians; they eat vegetarians.
Freezing or steaming the vegetables may help break down the cell walls, but why are you fighting against your carnivore’s natural needs? We are so ingrained with the idea that we should eat our veggies, that we carry it over to our pets. This is about love and love is good. But our dogs and cats are very different on the inside than we are and the best way to love them with food is to honour them as the carnivores that they are.