Dog breeds are dogs that have relatively uniform physical characteristics developed under controlled conditions by humans, with breeding animals selected for phenotypic traits such as size, coat color, structure, and behavior. The Fédération Cynologique Internationale recognizes over 400 pure dog breeds.
Other uses of the term breed when referring to dogs may include pure breeds, cross-breeds, mixed breeds and natural breeds.
Archaeology has revealed dog remains of various sizes but there does not appear to have been distinctive breeds until 3,000-4,000 years ago when greyhound-type dogs were depicted on pottery and paintings in Egypt and Western Asia. Mastiff-type dogs were kept for guarding and hunting, and short-legged dogs were also bred. By Roman times, most of the breed-types known today were well-defined and their qualities and functions recorded. Dog breeds proliferated in Europe during the Middle Ages 700 years ago. Most modern dog breeds are the products of the controlled breeding practices of the Victorian era (1830-1900), and the accurate documenting of pedigrees with the establishment of the English Kennel Club in 1873 in imitation of other stud book registries for cattle and horses.
Dogs have been selectively bred for thousands of years, sometimes by inbreeding dogs from the same ancestral lines, sometimes by mixing dogs from very different lines. The process continues today, resulting in a wide variety of breeds, hybrids, and types of dogs. As such, dogs are the only animal with such a wide variation in appearance without speciation, "from the Chihuahua to the Great Dane."
The following list uses a wide interpretation of "breed." Breeds are usually categorized by the functional type from which the breed was developed. The basic types are companion dogs, guard dogs, hunting dogs, herding dogs, and working dogs, although there are many other types and subtypes. Breeds listed here may be traditional breeds with long histories as registered breeds, rare breeds with their own registries, or new breeds that may still be under development.
In some cases, a breed's origin overlaps the boundaries of two or more countries; the dog is normally listed only in the country with which it is most commonly associated; for example, by its designated country according to the Fédération Cynologique Internationale (FCI). Some dogs, such as the Löwchen, have an uncertain origin and are listed under several countries.