Do dogs belong to cats?

Dogs, commonly known as dogs, are common canine mammals and close relatives of wolves. Dog is a kind of domestic animal domesticated by human beings not later than 14000 years ago-more likely 15000 years ago. Today, there are hundreds of domestic dogs. They range from just a dozen centimeters tall (such as Chihuahua puppies) to giant dogs nearly one meter high (such as Irish Wolfhounds), and their colors range from white to black, red, gray or brown. Domestic dogs, like humans, are highly socialized collective predators. This is probably why their overall behavior is trainable, interesting and suitable for human family and social environment. See dog training.

Although dogs are traditionally carnivores, this does not mean that domestic dogs only eat meat. Unlike other real carnivores such as cats, domestic dogs can live a healthy life on food such as vegetables and grains. In fact, their diet is very balanced. The diet of typical wild carnivores is nourished by the stomach contents of herbivores they capture, so their nutrition is often unbalanced. But domestic dogs have dealt with this well. They can be vegetarians, especially when these foods are paired with eggs or milk (that is, they are not strict vegetarians-although this is feasible). On the other hand, domestic dogs are more tolerant of meat than people, and will not suffer from metabolic diseases such as arterial obstruction because they eat more meat. In addition, scientists have also found that high-protein foods (eating a lot of meat) can help them prevent muscle tissue damage, such as the dog sled race in Idatarod, Alaska, and other similar situations that suffer from extreme stress.

Dogs play multiple roles in human society. The work of working dogs includes traditional work such as grazing, as well as new work such as detecting illegal transactions and helping the blind or disabled. For dogs who don't do traditional jobs, there are various dog sports that allow them to show their talents. In many countries, the most common and important social role of domestic dogs is as human companions. Dogs are so closely connected with all aspects of human work and life that they have won the reputation of "human's best friend".