Nutrition is the foundation of pet health. If the nutrition is correct, then your pet will thrive, ward off diseases naturally and generally live a longer, healthier life. If his or her nutrition is lacking, then your pet is subject to many diseases of aging and vitality. It only makes sense to feed our pets the types of food that they were created/evolved to eat. Dogs and cats are both carnivores although cats are obligate carnivores. This means that cats need to eat meat and are not designed to eat vegetables or grains. Dogs are scavengers but are carnivore scavengers. This means they can eat some grains and veggies to survive but need meat for optimum nutrition.
How do we know dogs are carnivores? Well look at their teeth–dogs have sharp,pointy teeth for tearing meat and jaws made for up and down motion for crushing prey. They have digestive tracts that are short and not a lot of enzymes to break down plants. Dogs require 22 amino acids but can produce only 12 of them–the rest come from a meat based diet. Herbivores with large stomachs and long digestive tracts can make all the amino acids they need, but not so with dogs and cats. Fat and protein are needed to supply the essentials that they need.
It does not make sense to feed a biologically inappropriate diet to a carnivore just because we, the animal guardians, do not like the idea of meat based diets. Dogs and cats should be fed a whole, unprocessed, species appropriate diet. If we as the guardians do not wish to eat animal products that is our choice, but we should not force that choice onto our dogs. Many of my friends and colleagues are vegetarians and vegans but they know that their dogs and cats can not do well on vegan diets. A vegan diet, even if it is endorsed by well meaning celebrities, is not appropriate for our pets unless the pets are herbivores like rabbits and guinea pigs. Dogs and cats are carnivores. For their health, feed them like carnivores.