Dogs are pretty special creatures. Not exactly carnivores, nor completely omnivores, but somewhere in between. Let’s see what makes them tick.
Digestive tract, length: 4-5 times the length of their body. For comparison, cat has 3 times, pig has 14 times and human about 17.
Digestive tract, weight / body weight: giant breeds 2.7%, miniature breeds 7%, cat 2.8-3.5% and human 11%.
Stomach, volume: dog 0.5-8 litres. Cat 0.3 l, human 1.5 l.
pH (acidity): dog 1-2, cat 1-2, human 2-4, wolves 1.
Dog’s sense of smell is million times more accurate than human’s: where we have about 5 million receptor cells in our nose epitel, dogs have aroung 150-250 million. Then again, dog has almost 1/10th of the taste receptors compared to us (dog about 1500, human about 10.000).
What does this mean?
Dog, direct descendant and relative of wolf, is mainly a meat eating animal. The thousands of years with human has evolved it into a scavenger, eating all edible that it can find. Thus dog is capable of consuming vegetable material, too: in fact it’s necessary for the bacterial flora in it’s stomach to have some fibres for well being.
The length of the bowels is that of a carnivore, a meat eater: short and effective. The time food remains within the system is approximately 12-30 hours, whereas for us human that is around 30-120 h (5 days). So the energy requirement for the food is high (energy/volume), and that can only be attained from meat and meat derivates (fat).
So the basic function is that the acute sense of smell can spot a rotting carcass miles away, and the low stomach pH can kill almost all pathogens causing intestinal infections. In addition to that, the lack of taste gives the opportunity to eat whatever edible other animals may have left due to bad taste.
In addition to this, dog’s stomach contains pepsinogen, a very effective enzyme that breaks collagen: it makes it possible for dogs to gain energy from the hard collagenous material like bones, cartilages and tendons, which otherwise are left in the carcass. Thus making it’s system capable of acting as a cleaning unit in nature, disposing of the bones of the carcasses.
Like all predatory animals, dogs also have one thing above us dorcile humans: their elastic stomach. It can stretch to hold up to 8 l of material, making it possible for the dog to consume HUGE amount on one eating. So its no wonder the neighbourgs poodle ate the 8 pound turkey the other christmas, as the legend goes: it can and has happened.
Interesting beasts these friends of ours, aren’t they?