I would emphasize that the dog’s body, yes, is less suited to digesting carbohydrates than humans, not producing ptyalin at the mouth level, being equipped, for example compared to humans, with a shorter intestinal tract and being practically devoid of diverticula (small fermentation chambers), having however expressed, thanks to domestication, genes that facilitate digestion, as I will describe later.
To complete, it could be specified how the lack of ptyalin, shorter intestine and absence of diverticula require the use, in the formulas, of precooked and unrefined cereals such as e.g. the whole ground corn kernel and brown rice (this thanks to the higher fiber intake). Trying to answer the question exhaustively, I make the following considerations. Recently in the sights of nutritionists, cereals have been accused of causing numerous problems and causing huge damage to the health of dogs and cats. The contamination that occurred a few years ago in the United States and Canada, with dangerous mycotoxins, led the market to orient itself towards grain-free products (Grain Free) and at the same time the idea also emerged that the dog, as a descendant of the wolf, is not able to digest them.
The dog is a non-obligate carnivore and has become, we can say almost omnivorous, with domestication. In fact, from the Neolithic onwards, the domestication of the wolf was carried out to protect populations from attacks by wild animals, effectively transforming the wolf’s specialization into its opposite. Later, when men became sedentary, they began to grow cereals to feed animals and dogs consequently were fed with scraps of human food, including cereals. From this coexistence between man and dog, the part of the genome responsible for the production of some neurotransmitters has changed, dogs have tried to interpret and understand the messages and behaviors of man, developing characteristics different from those of the wolf and an intelligence therefore , more “human-sized”. The genetic heritage has thus changed and, among other things, even the “wolf dog” has “learned” to digest cereals. In fact, in a very important study published in 2013 by Uppsala University, some geneticists analyzed the entire genome of 12 wolves and 60 dogs of different breeds, identifying 36 regions of the genome that differ from each other, even in all breeds considered. The genes involved are those responsible for the production of amylase and maltase, enzymes produced by the pancreas that participate in the degradation of carbohydrates and complex sugars; researchers have discovered that dogs had between 4 and 30 copies of these genes, while wolves only had two.
The result is that dogs are up to 5 times more efficient in assimilating carbohydrates than wolves. In a subsequent study, published on “Open Science” by the Royal Society of London and conducted by researchers from the Universities of Rennes and Grenoble together with CNRS in Lyon, DNA samples from bones and teeth from 13 ancient wolf remains found in different archaeological sites scattered throughout Eurasia and dating back to different epochs were instead analyzed. The result is an irregular progression of the wolf / dog genetic heritage, with samples equipped with very different quantities of specific genes, explainable only through the different behavior of three different human groups: those who remained hunters , gatherers and those who dedicated themselves to agriculture. Interestingly enough, the only two breeds of dogs that still have only two copies of Amy2B gene (the main enzyme for digesting starches) are Siberian Husky and Dingo , who lived with populations that until very recent times had a diet based almost exclusively on hunting or fishing products.