列出一个有关“犬”品种种类的分类列表。
以下是一些犬的品种分类列表：

按体型分类： toy dogs, small dogs, medium dogs, large dogs, giant dogs.

按原始用途分类： hunting dogs, herding dogs, guard dogs, sled dogs, companion dogs.

按毛发类型分类： short-haired dogs, long-haired dogs, wire-haired dogs, curly-haired dogs.

按国别分类： French breeds, Japanese breeds, German breeds, Chinese breeds, Russian breeds.