Miniature and Dwarf Animals
Dwarfism, and other conditions causing small stature, occur in most species of animal. Some examples are shown below. In cases of true dwarfism (rather than incremental selection for small size) the animals will often experience health problems. For that reasons most responsible breeders do not deliberately select for dwarfism. However some lines have selected bred for vigorous health, such as bantam lines of chickens and are well-recognized as a breed in their own right.
Indian Dwarf Cattle: A form of Zebu cattle called the Vechur is considered the smallest breed of cattle. India also has four dwarf breeds of Bos taurus, the Punganur, Iduki,Kasargod (show below) and Vatakara.
Dwarfism occurs in many different breeds of chicken. This includes true-breeding dwarf lines referred to as bantams. Bantams were first developed in Indonesia and spread worldwide by sailors who stocked them on voyages as a source of eggs and fresh meat. Another very old bantam breed is the Japanese bantam or chabo which was traditionally kept by aristocracy.
The smallest known horse is Thumbelina who is recognised by the Guinness Book of Records. Thumbelina is from a miniature breed but is also a dwarf, and so even smaller than is typical. Most miniature ponies were derived fom the already small Shetland pony. Selecting from small size has produced healthy ponies down to the size of a medium/large dog.
The smallest horse in the UK is Little Lucy. Another British pony with disproportionately short legs which have led to frequently false alarms when well meaning passers by called rescue services to report that she was stuck on the mud.
See also: vintage pics of tiny horses.
Ancon: Ancon (a.k.a. Otter) sheep are small, particularly in having short legs. At one time they were considered an example of how evolution can occur in leaps rather than gradual steps. But they are now recognized as achondroplastic dwarfs with a range of health problems rather than examples of an adaptive mutation. This breed is currently considered to be extinct.
Ouessan: By contrast the Ouessant (a.k.a. Ushant, Breton Dwarf) sheep is rare but still found both in its native home, the island of Ouessant of France, and a few other locations around the world. This breed is typical brown or black and has normal proportions, but extremely low weight and small stature.
There is currently a lot of demand for very small "teacup" versions of toy dog breeds. However these extremes of breeding often lead to poor health. Shown right is the Chihuahua "Heaven Sent Brandy".
German Shepherd: German shepherd dogs have a form of inherited dwarfism called juvenile panhypopituitarism. They also often have sparse coats and a shortened life-span.
Munchkin: Munchkin cats are not smaller overall , but they do have shorter front legs which can give the illusion of being a "miniature cat." Pedigree registries generally do not recognize munchkins as this is considered a deformity. There is also a cross between the Sphynx (hairless) and Munchkin (dwarf) cat which possessed both traits and is referred to as the Bambino--and a sparely-furred Rex/Munchkin cross breed called the Minskin. Further crosses go under putative breed names such as Kinkalow, Skookums, Dwelf and Lambkin.
Other: Other cats may be undersized for reason such as malnutrition and poor early care stunting their growth.
Rats: Dwarf rats are one fifth to one half the size of a normal rat. Dwarfism occurs spontaneously and many breeder have developed lines--some with significant health problems and shortened lifespans. Dwarfism is inherited as a simple recessive trait.
Mice: By contrast the Ames Dwarf Mouse lives considerably longer than a normal sized mouse. These 1/3 sized mice have difficulty maintaining their body temperature and so are normally housed with normal sized mice to keep them warm.
- Tantia, M. S., Vijh, R. K., Mishra, B., & Kumar, S. B. (2008). Genetic diversity among four short stature cattle populations of India. Animal Genetic Resources Information, 43, 15-23.