The "digestive characteristics" of dogs

Dogs belong to the carnivorous order in animal taxonomy. The ancestors of dogs mainly preyed on small animals and occasionally used tubers to satisfy their hunger. After dogs were trained by humans, their eating habits changed and became omnivores dominated by carnivores, but a vegetarian diet can also sustain life. Even so, they still maintain a meat-based digestive characteristic, such as dog teeth, each with a pair of sharp canine teeth, reflecting the characteristics of predators that are good at biting prey, and dogs' molars are also sharp and strong. Can cut off food, gnawing bones, the pressure between the upper and lower teeth can reach 165 kilograms, but not good at chewing. As a result, dogs really "gobble up" when they eat and seldom chew. The esophageal wall of the dog is rich in striated muscle and the vomiting center is well developed. When eating poison, it can cause a strong vomiting reflex and expel the poison swallowed into the stomach, which is a unique defense ability. The dog's salivary glands are well developed and can secrete large amounts of saliva, moisturizing the mouth and feed, making it easy to chew and swallow. Saliva also contains lysozyme, which has bactericidal effect. In the hot season, it depends on the evaporation of water in saliva to dissipate heat to regulate body temperature. Therefore, in summer we can often see dogs open their mouths and stick out their long tongues instead of sweating and dissipating heat. The dog's stomach is not pear-shaped, and the content of hydrochloric acid in gastric juice is 0.4-0.6%, ranking first among livestock. Hydrochloric acid can cause protein swelling and denaturation, which is convenient for decomposition and digestion. Therefore, dogs have a strong ability to digest protein, which is the basis of their meat-eating habits. Dogs can empty all the food in their stomach 5-7 hours after eating, much faster than other herbivores or omnivores. The intestines of dogs are shorter, generally only 3-4 times of body length, while those of horses and rabbits with monogastric stomachs are 12 times their body length. Dogs have thick intestinal walls and strong absorptive capacity, which are typical meat-eating characteristics. The liver of the dog is relatively large, equivalent to about 3% of the body weight, and the bile secreted is conducive to the absorption of fat. The defecation center of dogs is underdeveloped and cannot defecate in a moving state like other livestock.

Dogs can digest and absorb protein and fat very well, but they have poor digestibility of crude fiber because of insufficient chewing and short intestines. Therefore, when feeding vegetables to dogs, they should be chopped and cooked, not the whole piece or the whole tree.