Full-grown miniature pigs
Sus scrofa domesticus
A miniature pig (also mini pig, or micro pig) is a breed of pig developed and used for medical research or for use as a pet. Miniature pigs weigh between 75 pounds (34 kg) to 150 pounds (68 kg) when fully grown, while farm pigs may weigh more than 700 pounds (320 kg). They were first used for medical research in Europe before being introduced to the United States in the 1980s. Since then, the animals have been used in studies by scientists around the world, and have also risen in popularity as companion animals.
In the 1960s, pigs that grew to be 150–200 pounds (68–91 kg) were sent to zoos in Western nations and were used for medical research in the fields of toxicology, pharmacology, pulmonology, cardiology, aging, and as a source of organs for organ transplantation. These comparatively smaller pigs were easier to work with than the larger farm pigs, which typically reach weights of 300-500 pounds. Pot-bellied pigs also became a fixture in many zoological parks where their small stature, sway backs, and potbellies attracted the attention of visitors. The purchase of a few potbellied pigs by wealthy pet owners helped start a new trend in pet pigs.
The popularity of miniature pigs grew in the 1980s, with pet potbellied pigs appearing everywhere from New York apartment complexes to small hobby farms. However, the trend was short-lived, mostly due to city ordinances forbidding raising farm animals within the city limits. Furthermore, many owners came to realize that even a 165-pound pig was difficult to handle in most housing situations.
The 1990s and 2000s saw a rising trend of marketing pet pigs that were supposed to be much smaller than even the potbellied pigs, and therefore suitable pets for house and apartment owners. While multiple animal protection groups and pig breeders question or deny the existence of true "miniature pigs", there are currently breeders selling piglets claimed to be miniature pigs in North America and in the United Kingdom.
In the mid-1980s, Keith Connell of the Bowmanville Zoo in Ontario imported breeding potbellied pigs to Canada, which became the foundation for the potbellied pig in North America. Because of customs laws, only their offspring could be sold in the United States. US zoos were the main target for the piglets, but private owners soon began purchasing them as pets. 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.
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 15 inches (38 cm) tall and weighing under 55 pounds (25 kg). All of the foundation pigs were dual registered in PPRSI and MPPRSI.
In May 2015, the China Academy of Agricultural Science announced that its research team had successfully produced F-25 (the 25th generation) of inbred Chinese Wuzhishan Mini Pig (WZSP), with an inbreeding coefficient of 0.99519.
Miniature pigs, also known as micro pigs, pocket pigs, and or teacup pigs, have seen an increase in popularity as pets, especially following Paris Hilton's attempt to purchase one in 2009 (She ended up with a much larger breed.). They are intelligent animals and can be house-trained. They do not shed and tend to keep themselves clean.
Micro pigs can potentially make great pets, but there are considerably more risks involved when buying a micro pig over other common pets, such as cats or dogs. The biggest concern is that, since there is no established breed of "teacup pig", there is no guarantee that the pig sold as such will actually stay small. The risk of ending up with a large pig can be somewhat minimized by looking at the pig's parents and grandparents if possible. If they are on the smaller side, the odds are better that the pig will remain small. However, since pigs can breed years before they fully mature, unscrupulous or ignorant breeders may show off parent pigs which are not fully grown themselves, so have not reached their full adult size. Some breeders may falsely claim that a mini-pig is guaranteed to stay under a certain weight, and sometimes will recommend a diet regimen that starves the animal and unnaturally stunts its growth.
In 2012, the Juliana Pig Association & Registry (JPAR) was officially founded. This registry is concerned with the lineage and breeding of a subset group of miniature pigs called Juliana pigs. JPAR records lineage, size, and age on every pig entered and has an online database that is open to the public. JPAR has a breed standard, Code of Ethics for responsible breeding, and consequences to falsification of information for farms that make false claims about their pigs. As JPAR grows so does the consistency of this particular breed of miniature pig.
Some towns and cities have ordinances disallowing farm animals within city limits; a pig is usually considered a farm animal regardless of its size. As well, many small animal vets will not treat pigs. Since these animals have a life span of 15 to 20 years, they require long term commitment. Due to their ability to bond, combined with their need for attention, people who have limited time for a pet may find a pig far more than they can handle. Additionally, if pet pigs are not properly trained when they are young, just like a dog they can strive for dominance and become aggressive.
There are multiple animal rescue organizations set up to find new homes for pet pigs which have grown too large or otherwise unmanageable for their owners
Other notable references
- John Pukite (1999). A field guide to pigs. ISBN 1-56044-877-6.
- Sachs, DH; Galli, C (2009). "Genetic Manipulation in Pigs". Current Opinion in Organ Transplantation 14 (2): 148–153. doi:10.1097/mot.0b013e3283292549. PMC 2687522. PMID 19469029.
-  - Miniature Potbellied Pig Registry Service, ref>The Truth about "Tea Cup" Pigs
- "History". Miniature Potbellied Pig Registry Service, Inc. Retrieved 4 Feb 2013.
- About Miniature Potbellied Pigs - Miniature Potbellied Pig Registry Service, Inc.
- History of pigs in research Andrew David Thaler, on October 14th, 2012
- Mini Pig Care guide
- You must have been told a porky: 'Micro' pig grows to 25 stone and takes over its owners' home By Daily Mail Reporter PUBLISHED: 12:51 EST, 27 July 2012 | UPDATED: 15:00 EST, 27 July 2012
- Minimizing risk when buying a micro pig About Micro Pigs and their size - UK
- Teacup Pigs All the Rage, But Animal Welfare Group Urges People to do Homework Before Taking One Home October 28, 2009
- "Instead of providing breed-appropriate feed and portions, her breeder recommended tiny, toy breed puppy-appropriate food and water bowls." 
- Juliana Pig Association and Registry
- Pot Bellied Pigs as Pets
- http://www.teacuppigs.info/Mini-Yucatan-Pig.html Meet Rosie a Yucatan miniature pig] May 10, 2009 NECN.com
- Mini pigs are big success on farm 15 October 2007 BBC News