Dogs are domesticated from wolves. As early as in the hunter-gatherer era, people have domesticated dogs as hunting assistants. Dogs were the first domesticated livestock by humans.
Dogs are carnivores and need to be fed with more animal protein in their feed, supplemented by vegetarian ingredients, to ensure their normal growth and health. Dogs sometimes eat grass, but eat very little, and occasionally spit it out. Dogs eat grass not to fill up, but to clear the stomach, mainly because of the unique structure of the dog's stomach and intestines. The dog's stomach is very large, accounting for about 2/3 of the abdominal cavity, while the intestines are very short, accounting for about 1/3 of the abdominal cavity, so the dog basically uses the stomach to digest food and absorb nutrients, easy to digest meat food, not easy to digest leaves, grass and other things with "tendons". Although dogs are carnivores, they can survive on vegetables and grains when survival is difficult. Typical wild carnivores derive this type of dietary nutrition from the stomach contents of herbivores they capture. A high-protein diet (lots of meat) can help them prevent damage to muscle tissue. Dogs like to gnaw on bones. This is a habit left over from tearing up prey in its original state. We need to give it some bones regularly when feeding. Dogs commonly have the habit of feeding on humans and their own feces to varying degrees. Some studies have shown that dogs acquired this habit over tens of thousands of years of domestication with humans, which is one of the important sources of feces that dogs had to accept as food during the scarcity of food in early human societies, and there are also views that this is a manifestation of the dog's pathology in the event of insufficient food, malnutrition, lack of certain micronutrients, or parasitic diseases. This behavior can also be reduced when micronutrients are supplemented.
Puppies and older dogs sleep longer and younger, stronger dogs sleep less. Dogs are usually in a light sleep and can be awakened by the slightest movement, but there are times when they sleep heavily. In light sleep, the dog is in a prone position, with the head bent between the two front paws, often with one ear close to the ground. After a deep sleep, the dog is not easy to be woken up, sometimes issued a dreamy murmur, and accompanied by limbs of the twitching and head, ear shake. When asleep, it often lies on its side, with its whole body spread out. The look is very sound.
Dogs have a territorial habit, they occupy a certain range, and to protect from other animals. They use the anal gland secretion has a special odor, the sweat gland secretion of sweat between the toes and the hind limbs on the ground scratch painting, as a territorial mark. Dogs love to chase creatures, and man is to use this characteristic of the dog, let it drive sheep, cattle and protect humans themselves.