Reasons for rarity in dog breeds varies, but includes both the introduction of new breeds and the dying out of old ones. Wars and catastrophes can affect certain breed populations, as does mechanization of work once done by particular types of dogs, and hereditary health issues.
Similar to the hounds seen in Egyptian paintings, the pharaoh was widely believed extinct. Descendants of this ancient breed were discovered on the island of Malta, where they earned their keep catching rabbits. Like other sighthounds, this dog requires a fenced-in area and shouldn't be trusted off-leash, as this rare breed will bolt after some very common prey. Medium-size and good-natured, this chestnut-colored hound requires lots of exercise.
The chinook, a rare breed of sled dog, doesn't resemble better-known sledding canines such as the husky or malamute. This heavily muscled brown dog with a black muzzle sports either upright or dropped ears. In addition to their sledding acumen, chinooks make fine family pets. They're especially good with kids.
The Norwegian Lundehund traces its heritage back to the Viking era. This medium-size hound is known for joint flexibility. Unfortunately, it's also known for a hereditary gastrointestinal disease that makes nutrient absorption problematic.
The klee kai is basically a miniature Alaskan husky, developed by an Alaskan breeder. While its large ancestors were sled dogs, the klee kai was bred as a companion. In Inuit, klee kai means "little dog."
The Carolina dog predates European arrival in North America. This medium-size breed with upright ears resembles the Australian dingo, and many still live in the wild in the American South. Unlike other domestic female dogs, who go into heat twice a year, Carolina females only do so annually.
New Guinea Singing Dog
Native to New Guinea, the New Guinea singing dog is among the rarest of breeds. Small and resembling a fox, these little dogs get their name from the variety of vocalizations they're capable of producing. Shy by nature, they make good pets for people they trust.
Peruvian Inca Orchid
Even the name "Peruvian Inca orchid" sounds rare and exotic. These black-and-white dogs come in hairless and coated varieties, with the former requiring sunscreen and limited outdoor time to avoid sunburn. Peruvian Inca orchids are like hothouse flowers—they're reputedly very sensitive dogs whose feelings are easily hurt.
You might mistake the first Bergamasco you see for a terribly neglected dog, full of knotted and matted hair. That's actually what this rare breed is supposed to look like. This Italian sheepdog breed resembles an unkempt sheep, and can smell like one if you don't wipe his face after meals. He shouldn't be bathed with shampoo—the oils in his coat moisturize his skin and create natural water- and dirt-proofing.