Miniature Pigs, also called Mini Pig, Micro Pig, Teacup Pig or Pygmy Pig, are small breeds of domestic pig, such as the Vietnamese Pot-Bellied pig, Göttingen minipig, Juliana pig, Choctaw hog, or Kunekune (and specimens derived by crossbreeding these breeds). Miniature pigs can usually be distinguished from other pigs by their possession of small perked-back ears, a potbelly, a swayed back, a chubby figure, a rounded head, a short snout, short legs, a short neck, and a tail with thick hair at the end. Typically, miniature pigs will range in weight from about 70 pounds (32 kg) to 150 pounds (68 kg).
In the 1960s, Chinese pigs that grew to be 68–91 kilograms (150–200 lb) were sent to zoos in Western cities and were used for medical research in the fields of toxicology, pharmacology, pulmonology, cardiology, ageing, and as a source of organs for organ transplantation. These comparatively smaller pigs were easier to work with than larger pig breeds, which typically reach weights of 300–500 lb (140–230 kg).
In the mid-1980s, Keith Connell of the Bowmanville Zoo in Ontario imported breeding Vietnamese Pot-Bellied pigs to Canada, which became the foundation for the pot-bellied pig in North America. The breed is known for its small stature, swayed back, and pronounced potbelly. Because of custom laws, only their offspring could be sold in the United States. U.S. zoos were the main target for the piglets, but private owners soon began purchasing them as pets. Pet pot-bellied pigs started to appear everywhere; from New York apartment complexes to small suburban residences. Up to five additional imports were made in the following 10 years. To track the pedigrees, the Potbellied Pig Registry Service, Inc (PPRSI) was created to preserve these bloodlines and establish a breed registry in the United States. This registry was dissolved in the late 1990s. Today, most pot-bellied pigs are little to never purebred, as the pure breed is critically endangered.
The Miniature Potbellied Pig Registry Service, Inc (MPPRSI) was established in 1993 to provide a registry for those pigs who were pedigreed in the PPRSI and met the breed standard when fully grown not being more than 60 centimetres (24 in) tall and weighing under 80 kilograms (180 lb). All of the foundation pigs were dual-registered in the PPRSI and MPPRSI.
Beginning in the late 1960s at the Institute of Animal Breeding and Genetics (Institut für Tierzucht und Haustiergenetik) at the University of Göttingen, Germany, the Göttingen minipig was developed by crossbreeding the Minnesota minipig, the Vietnamese Pot-Bellied pig and the German Landrace pig. It is considered the smallest breed of domestic pig in the world.