狗 Dog

犬（学名：Canis lupus familiaris），現代俗称为狗或狗子，一种常见的犬科哺乳动物，生物学分类上是狼的一个亚種。狗是最早被驯化的一个物种。被人豢养的称为家犬，返回野外没人养的狗称为“野狗”或“流浪狗”。犬的壽命約十多年，與貓的平均壽命相近。若無發生意外，平均壽命以小型犬為長。

DNA分析显示狗不单单是灰狼（Canis lupus）的近亲，更是各地不同灰狼亚种的混血后代。现代狗的祖先约在1.1万至1.6万年前开始在西欧被人类驯化，更早的古代狗如在比利时所发现距今3.6万年及阿尔泰山所发现约3.3万年前的标本，则显示已经中断的驯化事件，这些更早期的古代狗均未留下现存后代。

狗被用来做各种事情：看家护院、捕猎、拉雪橇、拉车、警用、军用、做宠物、帮助身障人士等。

在西方文化裡，狗被称为“人类最好的朋友”。在另外一些地方，如東亞的韩国，中國个别地区(例如，吉林延边)，歐洲的瑞士，狗也被用来食用。

今天，家犬的种类已达数百个品种，其中多数犬种出现是近几百年的事。人们根据需要培育了许多不同的品种。身高从只有15.2厘米的吉娃娃到76厘米的爱尔兰猎狼犬，颜色也从白色到黑、灰或棕都有。长毛、短毛，直毛、卷毛，不一而足。

The domestic dog (Canis lupus familiaris or Canis familiaris) is a domesticated canid which has been selectively bred for millennia for various behaviors, sensory capabilities, and physical attributes.^[2]

Although initially thought to have originated as a manmade variant of an extant canid species (variously supposed as being the dhole,^[3] golden jackal,^[4] or gray wolf^[5]), extensive genetic studies undertaken during the 2010s indicate that dogs diverged from other wolf-like canids in Eurasia 40,000 years ago.^[6] Being the oldest domesticated animals, their long association with people has allowed dogs to be uniquely attuned to human behavior,^[7] as well as thrive on a starch-rich diet which would be inadequate for other canid species.^[8]

Dogs perform many roles for people, such as hunting, herding, pulling loads, protection, assisting police and military, companionship, and, more recently, aiding handicapped individuals. This impact on human society has given them the nickname "man's best friend" in the Western world. In some cultures, however, dogs are also a source of meat.^[9][10]