Editing Guinea pig (section)

== Importance ==

=== As pets ===
{{See also|List of guinea pig breeds}}

==== Social behaviors ====
If handled correctly early in life, guinea pigs become amenable to being picked up and carried and seldom bite or scratch.<ref name=harkness/> They are timid explorers who often hesitate to escape their cage even when an opportunity presents itself.{{sfn|Vanderlip|2003|p=20}} Still, they show considerable curiosity when allowed to walk freely, especially in familiar and safe terrain. Guinea pigs that become familiar with their owner will whistle on the owner's approach; they will also learn to whistle in response to the rustling of plastic bags or the opening of refrigerator doors, where their food is most commonly stored.

==== Coats and grooming ====
[[File:Rene the long-haired Satin Peruvian Guinea pig.jpg|thumb|right|A lilac, orange, and white [[Satin guinea pig|satin]] [[Peruvian guinea pig]] with a show-length coat|275x275px]]

Domesticated guinea pigs occur in many breeds that have developed since their introduction to Europe and North America. These varieties vary in hair and color composition. The most common variety found in pet stores is the English shorthair (also known as the American), which has a short, smooth coat, and the [[Abyssinian guinea pig|Abyssinian]], whose coat is ruffled with [[cowlick]]s, or [[rosette (zoology)|rosettes]]. Also popular among breeders are the [[Guinea pig breed#Peruvian|Peruvian]] and the [[Guinea pig breed#Silkie|Sheltie]] (or Silkie), both straight longhair breeds, and the [[Guinea pig breed#Texel|Texel]], a curly longhair. Grooming of guinea pigs is primarily accomplished using combs or brushes. Shorthair breeds are typically brushed weekly, while longhair breeds may require daily grooming.<ref>{{cite journal|title=Guinea Pigs: The Right Pet for You?|journal=The Humane Society of the United States|date=April 21, 2010|url=http://www.humanesociety.org/animals/guinea_pigs/tips/guinea_pigs_as_pets.html|access-date=25 June 2014|archive-date=27 June 2014|archive-url=https://web.archive.org/web/20140627185728/http://www.humanesociety.org/animals/guinea_pigs/tips/guinea_pigs_as_pets.html?}}</ref>

==== Clubs and associations ====
Cavy clubs and associations dedicated to the showing and breeding guinea pigs have been established worldwide. The American Cavy Breeders Association, an adjunct to the [[American Rabbit Breeders' Association]], is the governing body in the United States and Canada.<ref>{{cite web|title=Constitution |url=http://www.acbaonline.com/constitution.html |publisher=American Cavy Breeders Association |date=2006-09-29 |access-date=2007-03-22 |archive-url=https://web.archive.org/web/20070405184705/http://www.acbaonline.com/constitution.html |archive-date=2007-04-05 }}</ref> The [[British Cavy Council]] governs cavy clubs in the United Kingdom. Similar organizations exist in Australia (Australian National Cavy Council)<ref>{{cite web|url = http://cavycouncil.org.au/|title = Official Website|publisher = Australian National Cavy Council|access-date = 2007-04-03|archive-date = 2011-07-06|archive-url = https://web.archive.org/web/20110706124348/http://cavycouncil.org.au/}}</ref> and New Zealand (New Zealand Cavy Council).<ref>{{cite web|url = http://nzcavycouncil.org.nz/ |title = Official Website|publisher = New Zealand Cavy Council|access-date = 2015-02-26}}</ref> Each club publishes its standard of perfection and determines which breeds are eligible for showing.

==== Human allergies ====
[[Allergy|Allergic]] symptoms, including [[rhinitis]], [[conjunctivitis]], and [[asthma]], have been documented in laboratory animal workers who come into contact with guinea pigs.<ref name="ncbi.nlm.nih.gov">{{cite journal|title=Severe Allergic Reactions to Guinea Pig|journal= Clinical and Molecular Allergy|date=October 27, 2005|volume=3|issue=2005|page=14|pmc=1282583|last1=Zacharisen|first1=M. C.|last2=Levy|first2=M. B.|last3=Shaw|first3=J. L.|last4=Kurup|first4=V. P.|doi=10.1186/1476-7961-3-14|pmid=16253140|doi-access= free}}</ref><ref>{{cite web|title=Occupational Health and Safety for Staff with Substantial Contact with GUINEA PIGS|url=http://www.iacuc.ucsf.edu/Safe/awOhsGuineaPig.asp|publisher=University of California San Francisco|access-date=25 June 2014}}</ref> Allergic reactions following direct exposure to guinea pigs in domestic settings have also been reported.<ref name="ncbi.nlm.nih.gov"/> Two major guinea pig allergens, Cav p I and Cav p II, have been identified in guinea pig fluids (urine and saliva) and guinea pig [[dander]].{{update after|2021|3|15}}<!-- See https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6040002/ --><ref name="ncbi.nlm.nih.gov"/> People who are allergic to guinea pigs are usually allergic to hamsters and gerbils, as well.{{better source needed|date=November 2020}}{{medical citation needed|date=November 2020}}<ref>{{cite web|title=Pet Allergy Causes: Rodents|url=http://www.mayoclinic.org/diseases-conditions/pet-allergy/basics/causes/con-20028932|website=www.mayoclinic.org|publisher=Mayo Clinic|access-date=25 June 2014}}</ref> [[Allergy shots]] can successfully treat an allergy to guinea pigs. However, treatment can take up to 18 months.{{medical citation needed|date=November 2020}}

=== Traditional uses in Andean populations ===
Folklore traditions involving guinea pigs are numerous; they are exchanged as gifts, used in customary social and religious ceremonies, and frequently referred to in spoken metaphors.{{sfn|Morales|1995|pages=10–16, 45–74}} They also are used in traditional healing rituals by folk doctors, or ''[[curandero]]s'', who use the animals to diagnose diseases such as [[jaundice]], [[rheumatism]], [[arthritis]], and [[typhus]].{{sfn|Morales|1995|page=96}} They are rubbed against the bodies of the sick and are seen as a supernatural medium.{{sfn|Morales|1995|page=78}} Black guinea pigs are considered especially useful for diagnoses.{{sfn|Morales|1995|page=87–88}} The animal may be cut open and its entrails examined to determine whether the cure was effective.{{sfn|Morales|1995|page=83}} These methods are widely accepted in many parts of the Andes, where Western medicine is unavailable or distrusted.{{sfn|Morales|1995|page=75–78}}

Peruvians consume an estimated 65 million guinea pigs each year. The animal is so entrenched in the culture that one famous painting of the [[Last Supper]] in the [[Cusco Cathedral|main cathedral in Cusco]] shows [[Christ]] and his disciples dining on guinea pig.<ref name="cbs" /> The animal remains an important aspect of certain religious events in both rural and urban areas of Peru. A religious celebration, known as {{lang|es|jaca tsariy}} ("collecting the cuys"), is a major festival in many villages in the [[Antonio Raymondi Province|Antonio Raimondi]] province of eastern Peru and is celebrated in smaller ceremonies in [[Lima]].{{sfn|Morales|1995|pages=3, 101–112}} It is a [[syncretism|syncretistic]] event, combining elements of [[Catholicism]] and [[pre-Columbian]] religious practices, and revolves around the celebration of local [[patron saint]]s.{{sfn|Morales|1995|page=3}} The exact form the {{lang|es|jaca tsariy}} takes differs from town to town; in some localities, a ''sirvinti'' (servant) is appointed to go from door to door, collecting donations of guinea pigs, while in others, guinea pigs may be brought to a communal area to be released in a mock [[bullfighting|bullfight]].{{sfn|Morales|1995|page=3}} Meals such as ''cuy chactado'' are always served as part of these festivities, and the killing and serving of the animal are framed by some communities as a symbolic [[satire]] of local politicians or important figures.{{sfn|Morales|1995|page=3}} In the [[Tungurahua Province|Tungurahua]] and [[Cotopaxi Province|Cotopaxi]] provinces of central Ecuador, guinea pigs are employed in the celebrations surrounding the feast of [[Corpus Christi (feast)|Corpus Christi]] as part of the ''Ensayo'', which is a community meal, and the ''Octava'', where ''castillos'' (greased poles) are erected with prizes tied to the crossbars, from which several guinea pigs may be hung.{{sfn|Morales|1995|pages=119–126}} The Peruvian town of [[Churin]] has an annual festival that involves dressing guinea pigs in elaborate costumes for competition.<ref>{{cite web |date=2007-07-26 |title=Peruvians Pig-Out |url=http://itn.co.uk/89319c3295386535197a613d28bcf198.html |archive-url=https://web.archive.org/web/20090525000157/http://itn.co.uk/89319c3295386535197a613d28bcf198.html |archive-date=2009-05-25 |access-date=2007-07-29 |publisher=[[ITN]]}}</ref> There are also guinea pig festivals held in [[Huancayo]], [[Cusco]], [[Lima]], and [[Huacho]], featuring costumes and guinea pig dishes. Most guinea pig celebrations occur on National Guinea Pig Day (Día Nacional del Cuy) across Peru on the second Friday of October.<ref>{{Cite web |date=18 September 2013 |title=Declaran el segundo viernes de octubre será el Día Nacional del Cuy |url=https://rpp.pe/lima/actualidad/declaran-el-segundo-viernes-de-octubre-sera-el-dia-nacional-del-cuy-noticia-632118 |website=RPP}}</ref>

=== In popular culture and media ===
[[File:Page 54 Alice's Adventures in Wonderland (Carrol, Robinson, 1907).png|thumb|275x275px|Guinea pigs feature in ''[[Alice's Adventures in Wonderland]]'' (1907)]]
As a result of their widespread popularity, especially in households with children, guinea pigs have shown a presence in culture and media. Some noted appearances of the animal in [[literature]] include the short story "[[Pigs Is Pigs]]" by [[Ellis Parker Butler]], which is a tale of [[bureaucracy|bureaucratic]] incompetence. Two guinea pigs held at a railway station breed unchecked while humans argue whether they are "pigs" or "pets" to determine freight charges.<ref>{{cite book|last = Butler|first = Ellis Parker|title = Pigs is Pigs|url = https://archive.org/details/pigsispigs00cogoog|publisher = McClure, Phillips & Co|year = 1906|isbn = 978-0-585-07104-6}}</ref> Butler's story, in turn, inspired the ''[[Star Trek: The Original Series]]'' episode "[[The Trouble with Tribbles]]", written by [[David Gerrold]].<ref>Star Trek: The Original Series, [[Blu-ray]] edition, Season 2, Disc 4: "The Trouble with Tribbles," CBS Home Video: Catalog No. 07176</ref>

==== In children's literature ====
''[[The Fairy Caravan]]'', a novel by [[Beatrix Potter]],<ref>{{cite book|last = Potter|first = Beatrix|title = The Fairy Caravan|year = 1929|publisher = David McKay Co|isbn = 978-0-7232-4044-0}}</ref> and [[Michael Bond]]'s [[Olga da Polga]] series for children,<ref>{{cite book|last = Bond|first = Michael|title = The Tales of Olga da Polga|publisher = Macmillan|year = 2001|isbn = 978-0-19-275130-0}}</ref> both feature guinea pigs as the [[protagonist]]. Another appearance is in ''[[The Magician's Nephew]]'' by [[C. S. Lewis]]: in the first (chronologically) of his ''[[The Chronicles of Narnia]]'' series, a guinea pig is the first creature to travel to the [[Wood between the Worlds]].<ref>{{cite book|last = Lewis|first = C.S.|title = The Magician's Nephew|publisher = Macmillan|year = 1955|isbn = 978-1-56179-702-8}}</ref> In [[Ursula Dubosarsky]]'s ''Maisie and the Pinny Gig'', a little girl has a recurrent dream about a giant guinea pig, while guinea pigs feature significantly in several of Dubosarsky's other books, including the young adult novel ''The White Guinea Pig'' and ''The Game of the Goose''.<ref>[http://www.penguin.com.au/contributors/523/ursula-dubosarsky Ursula Dubosarsky]. penguin.com.au</ref>

==== In film and television ====
Guinea pigs have also been featured in film and television. In the TV movie ''[[Shredderman Rules]]'', the main character and the main character's crush both have guinea pigs, which play a minor part in the plot. A guinea pig named Rodney, voiced by [[Chris Rock]], was a prominent character in the 1998 film ''[[Dr. Dolittle (film)|Dr. Dolittle]]'', and Linny the Guinea Pig is a co-star on [[Nick Jr. (TV channel)|Nick Jr.]]'s ''[[Wonder Pets]]''. Guinea pigs were used in some major [[advertising|advertising campaigns]] in the 1990s and 2000s, notably for [[Egg Banking|Egg Banking plc]],<ref>{{cite web|url =http://connection.ebscohost.com/c/articles/32433910/slogan-doctor-egg-you-know-where-you-are-egg|archive-url =https://web.archive.org/web/20111107213230/http://connection.ebscohost.com/c/articles/32433910/slogan-doctor-egg-you-know-where-you-are-egg|archive-date =2011-11-07|title = Slogan Doctor Egg: 'You know where you are with egg'|author=Morrish, John|publisher = Management Today|access-date = 2011-07-18|date=May 2008|page=14}}</ref> [[Snapple]], and [[Blockbuster Inc.|Blockbuster Video]].<ref>{{cite web|last = LaMonica|first = Paul|title = Super Bowl Ads, Like the Game, Disappoint|publisher = CNNMoney|url = https://money.cnn.com/2007/02/05/news/companies/superbowlads/index.htm|date = 2007-02-05|access-date = 2011-07-19}}</ref> In the ''[[South Park]]'' [[South Park (season 12)|season 12]] episode "[[Pandemic 2: The Startling]]", giant guinea pigs dressed in costumes rampage over the Earth.<ref>According to the "Commentary Mini" for the episode, the "costumes" for the guinea pigs were not created by South Park Studios, but rather had been ordered on line from a woman who makes them. "Commentary Mini" for Episode 11, Season 12: ''Pandemic 2: The Startling''</ref> The 2009 [[Walt Disney Pictures]] movie ''[[G-Force (film)|G-Force]]'' features a group of highly intelligent guinea pigs trained as operatives of the U.S. government.<ref>[https://www.rogerebert.com/reviews/g-force-2009 "G-Force" Review]. [[Roger Ebert]], July 22, 2009.</ref>

=== As livestock ===<!-- This section is the target of an [[internal link]] from [[Taboo food and drink]] -->

==== In South America ====
[[File:Cuy or guinea pig, from the restaurant Fogon de los Abuelos in Matus, Ecuador.jpg|thumb|Dish from [[Ecuador]] called ''cuy'']]
[[File:Cuy Peruvian dish.jpg|thumb|A [[Peruvian cuisine|Peruvian dish]] made with ''cuy'']]
Guinea pigs (called ''cuy'', ''cuye'', or ''curí'') were originally domesticated for their meat in the Andes. Traditionally, the animal was reserved for ceremonial meals and as a [[delicacy]] by indigenous people in the Andean highlands. Still, since the 1960s, it has become more socially acceptable for consumption by all people.{{sfn|Morales|1995|page=47}} It continues to be a significant part of the diet in Peru and Bolivia, particularly in the Andes Mountains highlands; it is also eaten in some areas of Ecuador (mainly in the [[Geography of Ecuador#La Sierra (the highlands)|Sierra]]) and in Colombia,{{sfn|Morales|1995|pages=xxvi, 4, 32}} mainly in the southwestern part of the country ([[Cauca Department|Cauca]] and [[Nariño department|Nariño]] departments). Because guinea pigs require much less room than traditional [[livestock]] and reproduce extremely quickly, they are a more profitable source of food and income than many traditional stock animals, such as pigs and cattle;<ref name="Africa">{{cite journal|last = Nuwanyakpa|first = M.|title = The current stage and prospects of guinea pig production under smallholder conditions in West Africa|journal = Livestock Research for Rural Development|date=November 1997|volume = 9|issue = 5|url = http://www.lrrd.org/lrrd9/5/gp951.htm|access-date = 2007-04-16|display-authors=etal}}</ref> moreover, they can be raised in an urban environment. Both rural and urban families raise guinea pigs for supplementary income, and the animals are commonly bought and sold at local markets and large-scale municipal fairs.{{sfn|Morales|1995|pages=32–43}}

Guinea pig meat is high in [[protein]] and low in [[fat]] and [[cholesterol]], and is described as being similar to rabbit and the dark meat of [[chicken (food)|chicken]].<ref name="cbs" /><ref name="csmonitor">{{cite news|last = Mitchell|first = Chip|title = Guinea Pig: It's What's for Dinner|work = The Christian Science Monitor|url= http://www.csmonitor.com/2006/1101/p04s01-woam.html|date = 2006-11-01|access-date = 2007-03-12}}</ref> The animal may be served fried (''chactado'' or ''frito''), broiled (''asado''), or roasted (''al horno''), and in urban restaurants may also be served in a [[casserole]] or a [[fricassee]].<ref name="morales2">[[#Morales|Morales]], pp. 48–67.</ref> Ecuadorians commonly consume ''sopa'' or ''locro de cuy'', a soup dish.<ref name="morales2" /> ''[[Pachamanca]]'' or ''[[huatia]]'', an [[earth oven]] cooking method, is also popular, and cuy cooked this way is usually served with [[chicha]] (corn beer) in traditional settings.<ref name="morales2" />

==== In the United States, Europe, and Japan ====
Andean immigrants in New York City raise and sell guinea pigs for meat, and some South American restaurants in major cities in the United States serve ''cuy'' as a delicacy.{{sfn|Morales|1995|pages=xvii, 133–134}}<ref name="yamamoto2"/> In the 1990s and 2000s, La Molina University began exporting large-breed guinea pigs to Europe, Japan, and the United States in the hope of increasing human consumption outside of countries in northern South America.<ref name="cbs" />

==== Sub-Saharan Africa ====
Efforts have been made to promote guinea pig [[animal husbandry|husbandry]] in developing countries of [[West Africa]],<ref name=Africa/> where they occur more widely than generally known because they are usually not covered by livestock statistics. However, it has not been known when and where the animals have been introduced to Africa.<ref>Blench, R.M. 2000. African minor livestock species. In: Blench, R.M. and MacDonald, K.C. [https://books.google.com/books?id=sM2WZg3u5iQC&pg=PA314 The origins and development of African livestock: Archaeology, genetics, linguistics and enthnography]. University College London Press, London, UK; pp. 314–338 {{ISBN|1-84142-018-2}}.</ref> In [[Cameroon]], they are widely distributed.<ref>{{cite journal|pmid=9719838|year=1998|last1=Manjeli|first1=Y|last2=Tchoumboue|first2=J|last3=Njwe|first3=RM|last4=Teguia|first4=A|title=Guinea-pig productivity under traditional management|volume=30|issue=2|pages=115–22|journal=Tropical Animal Health and Production|doi=10.1023/A:1005099818044|s2cid=17847427}}</ref><ref>Ngou-Ngoupayou, J.D., Kouonmenioc, J., Fotso Tagny, J.M., Cicogna, M., Castroville, C., Rigoni, M. and Hardouin, J. 1995. [http://www.fao.org/ag/aga/agap/frg/feedback/war/v6200b/v6200b08.htm Possibilités de développement de l'élevage du cobaye en Afrique subsaharienne: le cas du Cameroun] {{Webarchive|url=https://web.archive.org/web/20120126123432/http://www.fao.org/ag/aga/agap/frg/feedback/war/v6200b/v6200b08.htm |date=2012-01-26 }}. World Animal Review (FAO/AGA) 83(2): 21–28</ref> In the [[Democratic Republic of the Congo]], they can be found both in peri-urban environments<ref>{{cite journal|pmid=17966272|year=2007|last1=Bindelle|first1=J|last2=Ilunga|first2=Y|last3=Delacollette|first3=M|last4=Kayij|first4=MM|last5=Di m'Balu|first5=JU|last6=Kindele|first6=E|last7=Buldgen|first7=A|title=Voluntary intake, chemical composition and in vitro digestibility of fresh forages fed to guinea pigs in periurban rearing systems of Kinshasa (Democratic Republic of Congo)|volume=39|issue=6|pages=419–26|journal=Tropical Animal Health and Production|doi=10.1007/s11250-007-9036-y|hdl=2268/19482|s2cid=33303439|url=http://orbi.uliege.be/handle/2268/19482}}</ref> as well as in rural regions, for example, in [[South Kivu]].<ref>Maass, B.L., Katunga-Musale, D., Chiuri, W.L., Zozo, R. and Peters, M. (2010) [http://www.tropentag.de/2010/abstracts/full/491.pdf Livelihoods of smallholders in South Kivu depend on small livestock: the case of the "cobaye"].</ref><ref>{{cite journal|author=Metre, T.K.|year=2011|url=http://www.rural21.com/uploads/media/Small_healthy_highyielding_01.pdf|title=Small, healthy, high-yielding|journal=Rural21 – the International Journal for Rural Development|volume=45|issue=1|pages=40–42 |archive-url=https://web.archive.org/web/20111005155855/http://www.rural21.com/uploads/media/Small_healthy_highyielding_01.pdf |archive-date=October 5, 2011}}</ref> They are also frequently held in rural households in [[Iringa Region]] of southwestern [[Tanzania]].<ref>
BACAS (Bureau for Agricultural Consultancy and Advisory Service). 2007. [http://www.cepf.net/Documents/UnileverTea_Tanzania_Tech_Report.pdf Analysis of the extent of human pressures and impact on natural forests of UNILEVER Tea Tanzania Limited (UTT)] {{Webarchive|url=https://web.archive.org/web/20110928061503/http://www.cepf.net/Documents/UnileverTea_Tanzania_Tech_Report.pdf |date=2011-09-28 }}. Final Report, BACAS, Sokoine University of Agriculture, Morogoro, Tanzania
</ref><ref>Matthiesen et al. (2011) [http://www.tropentag.de/2011/abstracts/links/Matthiesen_llDdf2DY.pdf Importance of guinea pig husbandry for the livelihood of rural people in Tanzania: A case study in Iringa Region.] Tropentag, October 5–7, 2011, Bonn.</ref>

==== Peruvian breeding program ====
[[File:Ollantaytambo-cuy.jpg|thumb|271x271px|Guinea pigs raised as [[livestock]]]]
Peruvian research universities, especially [[La Molina National Agrarian University]], began experimental programs in the 1960s intending to breed larger-sized guinea pigs.{{sfn|Morales|1995|page=16}} Subsequent university efforts have sought to change breeding and husbandry procedures in South America to make the raising of guinea pigs as livestock more economically sustainable.{{sfn|Morales|1995|pages=16–17}} The variety of guinea pig produced by La Molina is fast-growing and can weigh {{convert|3|kg|lb|abbr=on}}.<ref name="yamamoto2"/> All the large breeds of guinea pig are known as ''cuy mejorados'' and the pet breeds are known as ''cuy criollos''. The three original lines out of Peru were the ''Perú'' (weighing {{convert|800|g|abbr=on}} by 2 weeks), the ''Andina'', and the ''Inti''.<ref>{{Cite web |last=Zaldívar |first=Ing Lilia Chauca de |date=October 31, 1997 |title=Producción de cuyes (Cavia porcellus) |url=http://archive.org/details/bub_gb_VxLVzsZ5HWcC |publisher=Roma : Organización de las Naciones para la Agricultura y la Alimentación |via=Internet Archive}}</ref>

=== In scientific research ===
{{See also|Skinny pig}}
[[File:USDA-ARS Guinea Pig.jpg|thumb|left|upright|A guinea pig being examined by a veterinary medical officer for a study on [[leptospirosis]]]]
The use of guinea pigs in scientific experimentation dates back at least to the 17th century, when the Italian biologists [[Marcello Malpighi]] and [[Carlo Fracassati]] conducted [[vivisection]]s of guinea pigs in their examinations of [[anatomy|anatomic]] structures.<ref>{{cite book|last = Guerrini|first = Anita|title = Experimenting with Humans and Animals|publisher = Johns Hopkins|year = 2003|page = 42|isbn = 978-0-8018-7196-2}}</ref> In 1780, [[Antoine Lavoisier]] used a guinea pig in his experiments with the [[calorimeter]], a device used to measure heat production.<ref>{{cite journal|last1 = Buchholz|first1 = Andrea C|last2 = Schoeller|first2 = Dale A.|title = Is a Calorie a Calorie?|journal = American Journal of Clinical Nutrition|volume = 79|pages = 899S–906S |year = 2004|pmid = 15113737|issue = 5|doi = 10.1093/ajcn/79.5.899S|doi-access = free}}</ref> Guinea pigs played a major role in the establishment of [[germ theory of disease|germ theory]] in the late 19th century, through the experiments of [[Louis Pasteur]], [[Pierre Paul Émile Roux|Émile Roux]], and [[Robert Koch]].<ref>{{cite book|last = Guerrini|first = Anita|title = Experimenting with Humans and Animals|publisher = Johns Hopkins|year = 2003|isbn = 978-0-8018-7196-2|pages=98–104}}</ref> Guinea pigs have been [[animals in space|launched into orbital space flight]] several times, first by the [[Soviet Union|USSR]] on the [[Sputnik 9]] [[biosatellite]] of March 9, 1961 – with a successful recovery.<ref>{{cite web|last = Gray|first = Tara|url=https://history.nasa.gov/animals.html|title = A Brief History of Animals in Space|publisher = [[NASA|National Aeronautics and Space Administration]]|year = 1998|access-date = 2007-05-03}}</ref> [[China]] also launched and recovered a biosatellite in 1990 which included guinea pigs as passengers.<ref>{{cite news|url = http://www.cnn.com/2003/TECH/space/10/03/china.space.timeline/index.html?_s=PM:TECH|title = Timeline: China's Space Quest|publisher = CNN.com|date = 2004-01-05|access-date = 2007-05-03|url-status = live|archive-url = https://web.archive.org/web/20120121112706/http://articles.cnn.com/2003-10-03/tech/china.space.timeline_1_long-march-jiuquan-satellite-china?_s=PM%3ATECH|archive-date = 2012-01-21}}</ref>

Guinea pigs remained popular laboratory animals until the later 20th century: about 2.5 million guinea pigs were used annually in the U.S. for research in the 1960s,<ref name="gad">{{cite book|last = Gad|first = Shayne C.|title = Animal Models in Toxicology|publisher = Taylor & Francis|year = 2007|edition = 2nd|pages = 334–402|isbn = 978-0-8247-5407-5}}</ref> but that total decreased to about 375,000 by the mid-1990s.<ref name="harkness" /> As of 2007, they constitute about 2% of the current total of laboratory animals.<ref name="gad" /> In the past, they were widely used to standardize [[vaccine]]s and [[antiviral drug|antiviral agents]]; they were also often employed in studies on the production of [[antibody|antibodies]] in response to extreme [[allergy|allergic reactions]], or [[anaphylaxis]].<ref name="reid">{{cite book|last = Reid|first = Mary Elizabeth|title = The Guinea Pig in Research|year = 1958|publisher = Human Factors Research Bureau|pages = 62–70}}</ref> Less common uses included research in [[pharmacology]] and [[irradiation]].<ref name="reid" /> Since the middle 20th century, they have been replaced in laboratory contexts primarily by mice and rats. This is in part because research into the genetics of guinea pigs has lagged behind that of other rodents, although geneticists [[William Ernest Castle|W. E. Castle]] and [[Sewall Wright]] made some contributions to this area of study, especially regarding [[biological pigment|coat color]].<ref name="robinson" />{{sfn|Wagner|Manning|1976|p=100}} The guinea pig [[genome]] was [[DNA sequencing|sequenced]] in 2008 as part of the [[Mammalian Genome Project]], but the guinea pig sequence scaffolds have not been assigned to chromosomes.<ref>{{cite journal |last1=Romanenko |first1=Svetlana A. |last2=Perelman |first2=Polina L. |last3=Trifonov |first3=Vladimir A. |last4=Serdyukova |first4=Natalia A. |last5=Li |first5=Tangliang |last6=Fu |first6=Beiyuan |last7=O'Brien |first7=Patricia C. M. |last8=Ng |first8=Bee L. |last9=Nie |first9=Wenhui |last10=Liehr |first10=Thomas |last11=Stanyon |first11=Roscoe |last12=Graphodatsky |first12=Alexander S. |last13=Yang |first13=Fengtang |title=A First Generation Comparative Chromosome Map between Guinea Pig (Cavia porcellus) and Humans |journal=PLOS ONE |date=2015-05-26 |volume=10 |issue=5 |pages=e0127937 |doi=10.1371/journal.pone.0127937 |doi-access=free |pmid=26010445 |pmc=4444286|bibcode=2015PLoSO..1027937R }}</ref>

The guinea pig was most extensively used in research and diagnosis of [[infectious disease]]s.<ref name=reid/> Common uses included identification of [[brucellosis]], [[Chagas disease]], [[cholera]], [[diphtheria]], [[foot-and-mouth disease]], [[glanders]], [[Q fever]], [[Rocky Mountain spotted fever]], and various strains of [[typhus]].<ref name=reid/> They are still frequently used to diagnose [[tuberculosis]] since they are easily infected by human tuberculosis bacteria.<ref name=gad/> Because guinea pigs are one of the few animals which, like humans and other [[primate]]s, cannot synthesize vitamin C but must obtain it from their diet, they are ideal for researching scurvy.<ref name=gad/> From the accidental discovery in 1907 that scurvy could be induced in guinea pigs to their use to prove the chemical structure of the "scorbutic factor" in 1932, the guinea pig model proved a crucial part of vitamin C research.<ref>{{cite journal | pmid = 12555613 | volume=122 | issue=17 | title=[Axel Holst and Theodor Frolich—pioneers in the combat of scurvy] |date=June 2002 | journal=Tidsskr. Nor. Laegeforen. | pages=1686–7 | author=Norum KR, Grav HJ| last2=Grav }}</ref><ref>[http://profiles.nlm.nih.gov/WG/Views/Exhibit/narrative/szeged.html Story of Vitamin C's chemical discovery. Accessed January 21, 2010]. Profiles.nlm.nih.gov (1965-08-30). Retrieved on 2011-06-28.</ref>

[[File:Dwyn.jpg|thumb|Black [[skinny pig]]]]

[[Complement system|Complement]], an important component for [[serology]], was first isolated from the blood of the guinea pig.<ref name=gad/> Guinea pigs have an unusual insulin mutation,<ref>{{cite journal|last1 = Chan|first1 = Shu Jin|title = Guinea pig preproinsulin gene: an evolutionary compromise?|journal = [[Proceedings of the National Academy of Sciences USA]]|volume = 81|year = 1984|pages = 5046–5050|doi = 10.1073/pnas.81.16.5046|pmid = 6591179|last2 = Episkopou|first2 = V|last3 = Zeitlin|first3 = S|last4 = Karathanasis|first4 = SK|last5 = MacKrell|first5 = A|last6 = Steiner|first6 = DF|last7 = Efstratiadis|first7 = A|issue = 16|pmc = 391634|display-authors = 1|bibcode = 1984PNAS...81.5046C|doi-access = free}}</ref> and are a suitable species for the generation of anti-insulin antibodies.<ref>{{cite journal|last = Bowsher|first = Ronald|title = Sensitive RIA for the Specific Determination of Insulin Lispro|url = http://www.clinchem.org/cgi/content/full/45/1/104|journal = Clinical Chemistry|volume = 45|date=1 January 1999| pages = 104–110|access-date = 2007-03-15|pmid = 9895345|issue = 1|author2 = L|author3 = B|author4 = S|author5 = L|author6 = W|author7 = C|doi = 10.1093/clinchem/45.1.104|display-authors = 1|doi-access = free}}</ref> Present at a level 10 times that found in other mammals, the insulin in guinea pigs may be important in growth regulation, a role usually played by [[growth hormone]].<ref>{{cite journal|last = Adkins|first = Ronald|title = Molecular Phylogeny and Divergence Time Estimates for Major Rodent Groups: Evidence from Multiple Genes|journal = Molecular Biology and Evolution|volume = 18|date=1 May 2001| pages = 777–791|pmid = 11319262|issue = 5|author2 = G|author3 = R|author4 = H|doi = 10.1093/oxfordjournals.molbev.a003860|display-authors = 1|url = https://academic.oup.com/mbe/article-pdf/18/5/777/11168613/i0737-4038-018-05-0777.pdf|doi-access = free}}</ref> Additionally, guinea pigs have been identified as [[model organism]]s for the study of juvenile diabetes and, because of the frequency of pregnancy toxemia, of pre-eclampsia in human females.<ref name=percy/> Their placental structure is similar to that of humans, and their gestation period can be divided into trimesters that resemble the stages of fetal development in humans.<ref>Elsevier Academic Press(2012). "The Laboratory Rabbit, Guinea Pig, Hamster, and Other Rodents" p. 705 American College of Laboratory Animal Medicine. {{ISBN|0-12-380920-7}}.</ref>

Guinea pig [[strain (biology)|strains]] used in scientific research are primarily outbred strains. Aside from the typical American or English stock, the two main outbred strains in laboratory use are the Hartley and Dunkin-Hartley; these English strains are [[albinism|albino]], although pigmented strains are also available.{{sfn|Terril|Clemons|1998|pp=2–3}} [[Inbred strain]]s are less common and are usually used for very specific research, such as immune system molecular biology. Of the inbred strains that have been created, the two still used with any frequency are, following Sewall Wright's designations, "Strain 2" and "Strain 13".<ref name=robinson/>{{sfn|Terril|Clemons|1998|pp=2–3}}

Hairless breeds of guinea pigs have been used in scientific research since the 1980s, particularly for [[dermatology|dermatological]] studies. A hairless and [[immunodeficiency|immunodeficient]] breed was the result of a spontaneous genetic mutation in inbred laboratory strains from the Hartley stock at the [[Eastman Kodak|Eastman Kodak Company]] in 1979.<ref name=usamriid>{{cite web|last = Banks|first = Ron|url = http://netvet.wustl.edu/species/guinea/guinpig.txt|title = The Guinea Pig: Biology, Care, Identification, Nomenclature, Breeding, and Genetics|publisher = [[United States Army Medical Research Institute of Infectious Diseases|USAMRIID]] Seminar Series|date = 1989-02-17|access-date = 2007-05-23}}</ref> An immunocompetent hairless breed was also identified by the [[Institute Armand Frappier]] in 1978, and [[Charles River Laboratories]] has reproduced this breed for research since 1982.<ref>[http://www.criver.com/SiteCollectionDocuments/rm_rm_c_IAF_hairless_guinea_pigs.pdf IAF Hairless Guinea Pigs] {{Webarchive|url=https://web.archive.org/web/20081217004412/http://www.criver.com/SiteCollectionDocuments/rm_rm_c_IAF_hairless_guinea_pigs.pdf |date=2008-12-17 }}. [[Charles River Laboratories]]. Accessed October 2, 2008.</ref> Cavy fanciers then began acquiring hairless breeds, and the pet hairless varieties are referred to as "skinny pigs".