Vegetarian Diet For Dogs

Many people enjoy the vegetarian lifestyle today, either for health or ethical reasons. Some people choose to extend this dietary philosophy to their pets as well, which has prompted the marketing of commercial vegetarian dog and cat foods. There is a spectrum of foods and ingredients that may be included or excluded from a "vegetarian" diet, depending on one’s definition.

At minimum, it usually means that most meat sources are excluded from the diet (such as beef, pork, lamb, poultry, and sometimes fish). More restricted diets exclude other foods of animal origin, such as egg and dairy products. Perhaps the most extreme example would be a "vegan" diet, where all foods and ingredients of foods, including vitamin and mineral sources, are excluded if they are derived from animals. Provided foods are carefully combined in appropriate proportions, vegetarian or vegan diets for people can be very nutritious and tasty.

However, is the same true for dogs and cats?

Why feed a vegetarian diet to pets?

Many people consider their vegetarian diets to be more healthful than the traditional western diet that includes animal-source foods, and some assume the same to be true for dogs and cats. However, the health reasons that people cite as the basis for their own eating habits may not apply where pets are concerned. For example, dogs and cats do not suffer from problems such as high cholesterol or coronary artery disease at anywhere near the incidence as do humans. Thus, reducing intake of saturated fats and cholesterol by cutting meats out of the diet would not be of any real health benefit in pets.

Another concern may be about bacterial contamination of the meat ingredients, which could cause disease when consumed by pets. This may be a legitimate concern when eating raw or undercooked meat or poultry, but properly processed dry or canned pet foods pose a far lesser risk of disease transmission than raw fruits and vegetables. Some vegetarian diets for pets are also offered on the premise that they will prevent food allergies. The true incidence of food allergies in pets is relatively low.

Regardless, allergies can also be developed against proteins in plants just as easily, so cutting out the meat sources does little to prevent this problem.

Potential problems

For example, the protein and calcium needs of the dog and cat are much higher than those for humans. These nutrients are most easily provided through animal-derived ingredients. Some plants, such as soy, are high in protein, but the amino acids within the protein are not as balanced as they are for most animal-source ingredients. Dogs and cats also need a dietary source of vitamin B12, a substance not found in most plants.

All animals "need" this vitamin, but plant-eating animals such as cattle and sheep can make their own through the action of bacteria in their gastrointestinal tracts, provided there are adequate amounts of the mineral cobalt in the diet (which is found in plants). As mentioned above, the cat has even more unique nutritional requirements that make it harder to get adequate amounts of all required nutrients in the diet without using some animal-source ingredients.

Can’t these nutrients be replaced using synthetic substitutes? Yes, it is theoretically possible to formulate a diet that meets all these specific needs using synthetic additives.

However, it becomes more expensive and far less reliable to do it this way. Even when a product is formulated to meet the nutritional needs "on paper," it may not work in the "real" world. For example, plants also contain phytates, substances that bind calcium and trace minerals, lowering their "bioavailability." So, even when minerals are provided at levels that appear adequate, they cannot be properly absorbed and used by the animal.

There are adjustments in the AAFCO Dog and Cat Food Nutrient Profiles to account for decreases in bioavailability of nutrients, but these are made on the assumption that both animal and plant-source ingredients are used. It is impossible to tell whether these levels would still be adequate for a completely plant-based diet.