Whether dogs are, carnivores or omnivores is a recent debate that dog food manufacturers have started. Despite dogs being classified in the family Carnivora, kibble producers want you to believe that your dog is an omnivore so that they can add a high percentage of carbohydrates to your dog's food.
The ancestral diet of the wolf is comprised of 85-90% meat, primarily whole prey, which includes flesh, fur, bones, organs, and glands, small amounts of fish, and 10-15% grasses, nuts, berries, and other vegetation, most coming from the stomach contents of their small prey. This diet equals 49% protein, 44% fat, and 6% carbohydrates. Typical dry dog food contains 25% protein, 32% fat, and 43% carbohydrates.
Although the ancestral diet includes 6% carbohydrates, they are not derived from grains or starches. Carbohydrates consumed by the wolf are in the form of grasses, berries, nuts, and other vegetation in the stomach contents of prey, not ultra-processed sugars and starch found in kibble. Although there is a great range of carbohydrate percentages in kibble, some having as low as 5% carbohydrates, the typical kibble comprises 30-70% carbohydrates
So why does dog food contain a high level of carbohydrates? Because it is significantly less expensive to use starchy fillers than high-quality protein and fat sources in the kibble.
What is a Carnivore?
A carnivore is an animal that eats other animals. There are two types of carnivores: obligate carnivores, which rely entirely on obtaining their nutrients from meat, and facultative carnivores, which can get some of their nutrients from non-meat sources. Dogs are facultative carnivores.
Unique abilities of facultative carnivores include synthesizing taurine from cysteine and methionine, converting vitamin A from beta-carotene, and converting linoleic acid into arachidonic acid. Obligate carnivores are not able to perform these metabolic processes.
Carnivores share several characteristics. They possess large brains and are highly intelligent. Their digestive tract is short to allow food to pass through quickly. Carnivores have sharp teeth and claws to grab and hold onto their prey. Finally, carnivores have the status of a predator.
Dogs have all of the characteristics of a carnivore. Their powerful jaw is hinged to open fully but does not allow the lateral movement required to grind food. Their sharp premolars and molars simply break down food into small enough pieces to be swallowed. Amylase, the digestive enzyme found in the saliva of omnivores and herbivores, is absent in the saliva of dogs. The digestive process does not start until the food enters the stomach.
Why Some Believe Dogs Are Omnivores
Almost all animals classified in the Carnivora order are adapted to a predominantly carnivorous diet, obtaining a high percentage of their nutrients from animal proteins. A few species have adapted to an omnivorous diet composed of different portions of plant substances and animal substances. Some canids, such as the fox and the maned wolf, are opportunistic, feeding abundantly on seasonal fruits as they ripen.
Arguments for classifying dogs as omnivores center around two issues: the intestinal tract's length and the ability to digest starch. Let's examine these topics.
An omnivore's intestinal tract is six to sixteen times the length of its body, whereas a dog's intestinal tract is just two to three times the length of its body. A cat's intestinal tract, an obligate carnivore, is slightly shorter than a dog's.
Science has shown that it isn't just the length of the intestinal tract that determines if an animal is an omnivore or a carnivore; it is the "coefficient of fermentation" or the ability to extract nutrients from plant materials via fermentation.
Herbivores, such as cows, horses, and rabbits, have huge intestinal tracts to convert plant materials into nutrients through fermentation. They have a high coefficient of fermentation. Dogs, like other carnivores, cannot ferment food in their intestinal tract, so they have a low coefficient of fermentation. The coefficient of fermentation in the dog and cat is very comparable.
As dogs coevolved with humans, they began sharing the starch-based foods their human counterparts ate at the rise of agriculture. Modern science revealed how their diet altered the dogs' gene expression. A variance in the AMY2B gene allowed for the production of the enzyme amylase in the pancreas, enabling dogs to digest starchy foods like wheat, millet, and potatoes. Modern dogs do not have a set number of the AMY2B gene; some dogs have as few as three copies of the gene, while others have up to 32 copies. However, this gene variance isn't significant enough to alter the dog's entire digestive evolution.
Flaws in the Omnivore Theory
Dogs can survive on high levels of carbohydrates, but can they thrive? Studies are revealing that dogs are steadily losing years of life. One UK study showed that the mean longevity of purebred dogs in Britain has decreased by 11% in the past decade. In 1970, the average lifespan of a medium breed like the Golden Retriever was 17 years. Now, the average lifespan for Goldens is 9-10 years. With the introduction of kibble, cancer rates are also on the rise. This is not thriving.
Herbivores, such as ruminants, have a complex digestive system, some with multiple stomach chambers to ferment their food. Carnivores have a very simple digestive system, as meat is easily digested. Omnivores begin the digestion process in their mouth by thoroughly chewing their food. They have long, pointed teeth to tear meat and flat molars to crush plant materials. Much of the plant material consumed is eliminated as waste as it is not easily digested.
Just because your dog can digest glucose and starch does not mean you should feed him an ultra-processed diet, low in protein and fat but high in carbohydrates, primarily starch. Their diet should closely resemble the ancestral diet of the wolf. Simply, it should be an all-natural diet containing quality meat-based protein, natural fats and oils, and low in carbohydrates and starch. Help your dog thrive, not just survive.
Should fruits and vegetables be in my dog’s diet if the ancestral diet includes them?
The primary source of vegetation in the wolf diet is the stomach contents of small, non-ruminant prey. The wolf is also known to eat berries and other vegetation, likely to correct a nutrient imbalance.
Fruits and vegetables provide additional benefits to the raw diet. Fruits contain antioxidants that fight against free radicals, glucose, and soluble and insoluble fiber for gut health. Vegetables also provide soluble and insoluble fiber to your dog's diet. They also contain vitamins, minerals, and phytonutrients, filling in nutritional gaps caused by the lack of regular feeding of whole prey.
Takeaway Bites
- Dogs are facultative carnivores, meaning they can get a small portion of their nutrients from non-meat sources.
- Dogs have powerful jaws with teeth that can tear meat into small enough pieces to be swallowed. They cannot move that jaw laterally to grind plant materials efficiently.
- The ancestral diet consists of 85-90% meat, primarily whole prey, which includes flesh, fur, bones, organs, and glands, small amounts of fish, and 10-15% grasses, nuts, berries, and other vegetation, most coming from the stomach contents of their small prey.
References
- Carnivores, Omnivores, and Herbivores: Their Differences and Roles in the Food Chain
- Habib, Rodney; Becker, Karen Shaw. (2021). The Forever Dog. HarperCollins. Kindle Edition.
- Brady, C. (2020). In Feeding dogs: dry or raw? The science behind the debate. Farrow Road Publishing.