View source for Guinea pig

{{short description|Domesticated rodent from South America}}
{{About|the small species of Rodent|various guinea pig species|Cavia|other uses}}
{{distinguish|Guinea hog|Pig}}
{{pp-semi-indef|small=yes}}
{{pp-move}}
{{speciesbox
| name = Domestic guinea pig
| image = George the amazing guinea pig.jpg
| image_caption =
| status = DOM 
| genus = Cavia
| species = porcellus
| authority = ([[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]])
| synonyms = {{species list
    |Mus porcellus| Linnaeus,&nbsp;1758
    |Cavia cobaya| [[Peter Simon Pallas|Pallas]],&nbsp;1766
    |Cavia anolaimae| [[Joel Asaph Allen|J. A. Allen]],&nbsp;1916
    |Cavia cutleri| [[Edward Turner Bennett|Bennett]],&nbsp;1836
    |Cavia leucopyga| [[Jean Louis Cabanis|Cabanis]],&nbsp;1848
    |Cavia longipilis| [[Leopold Fitzinger|Fitzinger]],&nbsp;1879
    }}
}}
[[File:Guinea Pig Defense Sound.ogg|thumb|Guinea pig defense sound]]
The '''guinea pig''' or '''domestic guinea pig''' ('''''Cavia porcellus'''''), also known as the '''cavy''' or '''domestic cavy''' ({{IPAc-en|'|k|eɪ|v|i}} {{respell|KAY|vee}}), is a species of [[rodent]] belonging to the genus ''[[Cavia]]'', family [[Caviidae]]. [[Animal fancy|Breeders]] tend to use the name "cavy" for the animal, but "guinea pig" is more commonly used in scientific and laboratory contexts.{{sfn|Wagner|Manning|1976|p=2}} Despite their name, guinea pigs are not native to [[Guinea (region)|Guinea]], nor are they closely related to [[suidae|pig]]s. Instead, they originated in the [[Andes]] region of [[South America]], where wild guinea pigs can still be found today.<ref>{{cite book|last=Petrylak |first=Ashley |date=2009|title=Guinea Pigs (Great Pets)|url=|publisher=Cavendish Square Publishing|page=5|isbn=978-0-7614-4148-9}}</ref> Studies based on [[biochemistry]] and DNA [[Hybrid (biology)|hybridization]] suggest they are [[domestication|domesticated]] animals that do not exist naturally in the wild, but are descendants of a closely related cavy species such as ''[[Montane guinea pig|C.&nbsp;tschudii]]''.<ref name=weir/><ref name=Walker>{{cite book|last = Nowak|first = Ronald M.|title = Walker's Mammals of the World, 6th edition|publisher = Johns Hopkins University Press|year = 1999|isbn = 978-0-8018-5789-8}}</ref> Originally, they were domesticated as [[livestock]] (source of meat) in the Andean region and are still consumed in some parts of the world.<ref>{{Cite web |last=Peru |first=Eat |title=Eating Cuy: Peruvian Guinea Pig Delicacy - Eat Peru |url=https://www.eatperu.com/eating-cuy-guinea-pig-peruvian-delicacy/ |access-date=2024-10-21 |website=www.eatperu.com/ |language=en-US}}</ref>

<!-- As pets -->In [[Western world|Western society]], the guinea pig has enjoyed widespread popularity as a [[pet]] since its introduction to Europe and North America by European traders in the 16th century. Their docile nature, friendly responsiveness to handling and feeding, and the relative ease of caring for them have continued to make guinea pigs a popular choice of household pets. Consequently, organizations devoted to the [[Animal fancy|competitive breeding]] of guinea pigs have been formed worldwide. Through [[Selective breeding|artificial selection]], many [[Guinea pig breed|specialized breeds]] with varying [[Coat (animal)|coat]] colors and textures have been selected by [[Breeder|breeders.]]

<!-- In South America -->Livestock breeds of guinea pig play an important role in [[folk culture]] for many [[Indigenous peoples of the Andes|indigenous Andean peoples]], especially as a food source.<ref name=leonard>{{cite book
 |last=Leonard
 |first=Jonathan Norton
 |date=1970
 |title=Recipes, Latin American cooking
 |url=https://books.google.com/books?id=J8SLxAEACAAJ
 |location=
 |publisher=Time-Life International (Nederlands)
 |page= 21
 |isbn=978-0-8094-0063-8
}}</ref> They are not only used in [[traditional medicine|folk medicine]] and in community religious ceremonies{{sfn|Morales|1995}} but also raised for their meat. Guinea pigs are an important culinary staple in the [[Andes Mountains]], where it is known as ''cuy''. In the mid-2000s, marketers sought to expand its consumption beyond South America.<ref name="cbs">{{cite news|last = Vecchio|first = Rick|title = Peru Pushes Guinea Pigs as Food|work = [[CBS News]]|url = https://www.cbsnews.com/news/peru-pushes-guinea-pigs-as-food/|date = 2004-10-19|access-date = 2007-03-12}}</ref>

<!-- As test subjects -->[[Animal testing|Biological experimentation]] on domestic guinea pigs has been carried out since the 17th century. The animals were used so frequently as [[model organism]]s in the 19th and 20th centuries that the [[epithet]] ''guinea pig'' came into use to describe a [[human subject research|human test subject]]. Since that time, they have mainly been replaced by other rodents, such as [[Laboratory mouse|mice]] and [[Laboratory rat|rats]]. However, they are still used in research, primarily as models to study such human medical conditions as [[diabetes mellitus type 1|juvenile diabetes]], [[tuberculosis]], [[scurvy]] (like humans, they require dietary intake of [[vitamin C]]), and [[pre-eclampsia|pregnancy complications]].

==History==
[[File:Guinea pig skull. Cavia porcellus 02.jpg|thumb|Skull of a guinea pig]]
''Cavia porcellus'' is not found naturally in the wild; it is likely descended from closely related species of [[cavia|cavies]], such as ''[[Brazilian guinea pig|C.&nbsp;aperea]]'', ''[[Shiny guinea pig|C.&nbsp;fulgida]]'', and ''[[Montane guinea pig|C.&nbsp;tschudii]]''. These closely related species are still commonly found in various regions of South America.<ref name=weir/> Studies from 2007 to 2010 applying [[molecular marker]]s,<ref>{{Cite journal |last1=Spotorno |first1=A. E. |last2=Marín |first2=J. C. |last3=Manríquez |first3=G. |last4=Valladares |first4=J. P. |last5=Rico |first5=E. |last6=Rivas |first6=C. |year=2006 |title=Ancient and modern steps during domestication of guinea pigs (''Cavia porcellus'' L.) |journal=Journal of Zoology |volume=270 |issue=1 |pages=57–62 |doi=10.1111/j.1469-7998.2006.00117.x|s2cid=56219784 |hdl=10533/178756|hdl-access=free }}</ref><ref>{{cite journal|doi=10.1111/j.1439-0469.2009.00561.x|title=Molecular systematics, taxonomy and biogeography of the genus Cavia (Rodentia: Caviidae)|year=2010|last1=Dunnum|first1=Jonathan L.|last2=Salazar-Bravo|first2=Jorge|journal=Journal of Zoological Systematics and Evolutionary Research|volume=48|issue=4|pages=376–388|s2cid=18000863|doi-access=free}}</ref> and morphometric studies on the skull and skeletal [[Morphology (biology)|morphology]] of current and mummified animals<ref>{{Cite book |title=The quintessential naturalist: honoring the life and legacy of Oliver P. Pearson |last1=Spotorno |first1=A. E. |last2=Manríquez |first2=G. |last3=Fernández |first3=L. A. |last4=Marín |first4=J. C. |last5=González |first5=F. |last6=Wheeler |first6=J. |date=2007 |publisher=University of California Press |isbn=978-0-520-09859-6 |editor-last=Kelt |editor-first=D. A. |series=University of California Publications in Zoology |volume=134 |location=Berkeley |pages=367–388 |chapter=Domestication of guinea pigs from a southern Peru-northern Chile wild species and their middle pre-Columbian mummies |oclc=122715394 |editor-last2=Lessa |editor-first2=E.P. |editor-last3=Salazar-Bravo |editor-first3=J. |editor-last4=Patton |editor-first4=J. L. |chapter-url={{google books|id=PVIJr-aA-XMC|pg=PA367|plainurl=yes}}}}</ref> revealed the ancestor to be most likely ''C.&nbsp;tschudii''. Some species of cavy, identified in the 20th century as ''[[Cavia anolaimae|C.&nbsp;anolaimae]]'' and ''[[Cavia guianae|C.&nbsp;guianae]]'', may be domestic guinea pigs that have become [[feral]] by reintroduction into the wild.<ref name=walker/>

Regionally known as ''cuy'' (a Spanish word derived from the [[Quechuan languages|Quechua]] ''quwi''), the guinea pig was first [[domestication|domesticated]] as early as 5000&nbsp;BC for food by tribes in the [[Andes|Andean]] region of [[South America]] (the present-day southern part of Colombia, Ecuador, Peru, and Bolivia),{{sfn|Morales|1995|page=3}} some thousands of years after the domestication of the South American [[camelid]]s.<ref>{{cite book|ref=Chazan|last = Chazan|first = Michael|title = World Prehistory and Archaeology: Pathways through Time|year = 2008|publisher = Pearson Education, Inc.|isbn = 978-0-205-40621-0|page=272}}</ref> The [[Moche (culture)|Moche]] people of ancient Peru worshipped animals and often depicted the guinea pig in their art.<ref>Berrin, Katherine & Larco Museum. ''The Spirit of Ancient Peru: Treasures from the [[Larco Museum|Museo Arqueológico Rafael Larco Herrera]].'' New York: [[Thames & Hudson]], 1997.</ref>

Early accounts from Spanish settlers state that guinea pigs were the preferred sacrificial animal of the Inca people native to Peru.<ref>{{cite journal |last1=Valdez |first1=Lidio M. |title=Inka Sacrificial Guinea Pigs from Tambo Viejo, Peru |journal=International Journal of Osteoarchaeology |date=2019 |volume=29 |issue=4 |page=595 |doi=10.1002/oa.2755 |s2cid=132682067 |url=https://onlinelibrary.wiley.com/doi/epdf/10.1002/oa.2755|url-access=subscription }}</ref> These claims are supported by archaeological digs and transcribed Quechua mythology,<ref>{{cite journal |last1=Sandweiss |first1=Daniel H. |last2=Wing |first2=Elizabeth S. |title=Ritual Rodents: The Guinea Pigs of Chincha, Peru |journal=[[Journal of Field Archaeology]] |date=1997 |volume=21 |issue=1 |page=50 |doi=10.2307/530560 |jstor=530560 }}</ref> providing evidence that sacrificial rituals involving guinea pigs served many purposes in society such as appeasing the gods, accompanying the dead, or reading the future.<ref>{{cite journal |last1=Sandweiss |first1=Daniel H. |last2=Wing |first2=Elizabeth S. |title=Ritual Rodents: The Guinea Pigs of Chincha, Peru |journal=Journal of Field Archaeology |date=1997 |volume=24 |issue=1 |page=54 |doi=10.2307/530560 |jstor=530560 }}</ref>

From about 1200 to the [[Spanish conquest of the Inca Empire|Spanish conquest]] in 1532, the indigenous people used selective breeding to develop many varieties of domestic guinea pigs, forming the basis for some modern domestic breeds.<ref name="walker">{{cite book|last = Nowak|first = Ronald M.|title = Walker's Mammals of the World|url = https://archive.org/details/walkersmammalsof0001nowa|url-access = registration|edition = 6th|year = 1999|pages = 1667–1669|isbn = 978-0-8018-5789-8|publisher = Johns Hopkins University Press|location = Baltimore, Md.}}</ref> They continue to be a food source in the region; many households in the Andean highlands raise the animal.{{sfn|Morales|1995|page=8}}[[File:Three Unknown Elizabethan Children.jpg|thumb|right|c. 1580 painting of Elizabethan children with a cavy pet]]

In the early 1500s, [[Spanish Empire|Spanish]], [[Dutch Empire|Dutch]], and [[British Empire|English]] traders took guinea pigs to Europe, where they quickly became popular as [[exotic pet]]s among the upper classes and royalty, including [[Elizabeth I of England|Queen Elizabeth I]].{{sfn|Morales|1995|page=3}}<ref>{{cite book|last=Petrylak |first=Ashley |date=2009|title=Guinea Pigs (Great Pets)|url=|publisher=Cavendish Square Publishing|page=6|isbn=978-0-7614-4148-9}}</ref> The earliest known written account of the guinea pig dates from 1547, in a description of the animal from [[Santo Domingo]]. Because cavies are not native to [[Hispaniola]], the animal was believed to have been earlier introduced there by Spanish travelers.<ref name="weir">{{Cite book|last = Weir|first = Barbara J.|contribution = Notes on the Origin of the Domestic Guinea-Pig|editor-last = Rowlands|editor-first = I. W.|editor2-last = Weir|editor2-first = Barbara J.|title = The Biology of Hystricomorph Rodents|publisher = Academic Press|year = 1974|pages = [https://archive.org/details/conceptsofhumane0000unse/page/437 437–446]|isbn = 978-0-12-613333-2|url = https://archive.org/details/conceptsofhumane0000unse/page/437}}</ref> However, based on more recent excavations on West Indian islands, the animal may have been introduced to the Caribbean around 500 BC by ceramic-making horticulturalists from South America.<ref>Newsom and Wing, 2004, cited in {{cite journal|author1=Fitzpatrick, S.M. |author2=Keegan, W.F. |year=2007|title= Human impacts and adaptations in the Caribbean Islands: an historical ecology approach|journal= Earth and Environmental Science Transactions of the Royal Society of Edinburgh |volume=98|issue=1 |pages=29–45|doi=10.1017/S1755691007000096 |bibcode=2007EESTR..98...29F |s2cid=128704578 }}</ref> It was present in the [[Ostionoid]] period on [[Puerto Rico]], for example, long before the advent of the Spaniards.<ref>deFranca, S.D., Hadden, C.S., LeFebvre, M.J. and DuChemin, G. 2010. "Animal use at the Tibes Ceremonial Center." In: Curet, A. and Stringer, L.M. (eds.). ''Tibes: People, power, and ritual at the center of the cosmos.'' The University of Alabama Press, Tuscaloosa, Alabama, USA. pp. 115–151.</ref>

The guinea pig was first described in the West in 1554 by the [[Switzerland|Swiss]] [[naturalist]] [[Conrad Gessner]].<ref>{{cite book|last = Gmelig-Nijboer|first = C. A.|title = Conrad Gessner's "Historia Animalum": An Inventory of Renaissance Zoology|year = 1977|publisher = Krips Repro B.V.|pages = 69–70}}</ref> Its [[binomial nomenclature|binomial scientific name]] was first used by [[Johann Christian Polycarp Erxleben|Erxleben]] in 1777; it is an amalgam of [[Peter Simon Pallas|Pallas]]' [[Genus name|generic]] designation (1766) and [[Carl Linnaeus|Linnaeus]]' [[specific name (zoology)|specific]] conferral (1758).<ref name="weir" />

The earliest-known European illustration of a domestic guinea pig is a painting (artist unknown) in the collection of the [[National Portrait Gallery, London|National Portrait Gallery]] in London, dated to 1580, which shows a girl in a typical Elizabethan dress holding a tortoise-shell guinea pig in her hands. She is flanked by her two brothers, one of whom holds a pet bird.<ref name="TeleCavy">Reported, with colour illustration, in ''[[The Daily Telegraph]]'', London, 21 August 2013.</ref> The picture dates from the same period as the oldest recorded guinea pig remains in England, which are a partial cavy skeleton found at [[Hill Hall (Essex)|Hill Hall]], an Elizabethan manor house in [[Essex]], and dated to around 1575.<ref name="TeleCavy" />

==Nomenclature==

=== Latin name ===
The scientific name of the common species is ''Cavia porcellus'', with ''{{lang|la|[[wikt:porcellus|porcellus]]}}'' being [[Latin]] for "[[diminutive|little]] pig". ''Cavia'' is [[Neo-Latin]]; it is derived from ''cabiai'', the animal's name in the language of the [[Galibi]] tribes once native to [[French Guiana]].<ref>{{cite web |title=Cavy |url=http://dictionary.oed.com/ |archive-url=https://web.archive.org/web/20060625103623/http://dictionary.oed.com/ |archive-date=2006-06-25 |access-date=2007-04-25 |publisher=Oxford English Dictionary online (subscription access required)}}</ref> ''Cabiai'' may be an adaptation of the [[Portuguese language|Portuguese]] {{Lang|pt|çavia}} (now {{Lang|pt|savia}}), which is itself derived from the [[Tupian languages|Tupi]] word {{Lang|tup|saujá}}, meaning rat.<ref>{{cite encyclopedia |title=Definition of cavy |dictionary=Merriam-Webster Online |url=http://www.m-w.com/cgi-bin/dictionary?book=Dictionary&va=cavy |access-date=2007-03-12 |archive-url=https://web.archive.org/web/20080121221309/http://www.m-w.com/cgi-bin/dictionary?book=Dictionary&va=cavy |archive-date=2008-01-21}}</ref>

=== Guinea pig ===
The origin of "guinea" in "guinea pig" is hard to explain. One proposed explanation is that the animals were brought to Europe by way of [[Guinea (region)|Guinea]], leading people to think they had originated there.{{sfn|Wagner|Manning|1976|p=2}} "Guinea" was also frequently used in English to refer generally to any far-off, unknown country, so the name may be a colorful reference to the [[Exotic pet|animal's exotic origins]].<ref name="dictionary">{{cite encyclopedia |title=Results for "Guinea pig" |dictionary=Dictionary.com |url=http://dictionary.reference.com/browse/Guinea%20pig |access-date=2006-08-29}}</ref><ref>{{Cite EB1911|wstitle=Cavy}}</ref>

Another hypothesis suggests the "guinea" in the name is a corruption of "[[The Guianas|Guiana]]", an area in South America.<ref name="dictionary" />{{sfn|Wagner|Manning|1976|pp=2–3}} A common misconception is that they were so named because they were sold for the price of a [[Guinea (British coin)|guinea coin]]. This hypothesis is untenable because the guinea was first struck in England in 1663, and [[William Harvey]] used the term "Ginny-pig" as early as 1653.<ref>{{cite book |last=Harvey |first=William |title=Anatomical exercitations concerning the generation of living creatures to which are added particular discourses of births and of conceptions, &c |year=1653 |page=527}}</ref> Others believe "guinea" may be an alteration of the word [[wikt:coney|coney]] (rabbit); guinea pigs were referred to as "pig coneys" in [[Edward Topsell]]'s 1607 treatise on [[quadrupedalism|quadrupeds]].{{sfn|Wagner|Manning|1976|p=2}}

How the animals came to be called "pigs" is not clear. They are built somewhat like pigs, with large heads relative to their bodies, stout necks, and rounded rumps with no tail of any consequence; some of the sounds they emit are very similar to those made by pigs, and they spend a large amount of time eating.{{sfn|Wagner|Manning|1976|p=2}}{{sfn|Terril|Clemons|1998|p=2}} They can survive for long periods in small quarters, like a "pig pen", and were easily transported by ship to Europe.{{sfn|Wagner|Manning|1976|p=2}}

=== Other languages ===
Guinea pigs are called ''{{lang|qu|quwi}}'' or ''{{lang|qu|jaca}}'' in [[Quechuan languages|Quechua]] and {{lang|es|cuy}} or {{lang|es|cuyo}} (plural ''cuyes, cuyos'') in the [[Spanish language|Spanish]] of Ecuador, Peru, and Bolivia.<ref name="diccionario">{{cite web |title=Diccionario de la Lengua Española |url=http://buscon.rae.es/draeI/ |access-date=2007-03-12 |publisher=Real Academia Española |language=es}}</ref>

Many of the animal's names allude to pigs. The [[German language|German]] word is {{lang|de|Meerschweinchen}}, literally "little sea pig", apparently because they were brought to Germany from overseas.<ref>{{cite web|title=Meerschweinchen|publisher=Digitales Wörterbuch der deutschen Sprache|url=https://www.dwds.de/wb/Meerschweinchen|access-date=4 July 2025}}</ref> Similarly, in [[Polish language|Polish]] they are called {{lang|pl|świnka morska}}, in [[Hungarian language|Hungarian]] {{lang|hu|tengerimalac}}, and in [[Russian language|Russian]] {{lang|ru|морская свинка}} ({{transliteration|ru|morskaya svinka}}).

The [[French language|French]] term is ''[[wikt:fr:cavia|cochon d'Inde]]'' (Indian pig) or ''cobaye''; the [[Netherlands|Dutch]] called it ''[[wikt:nl:cavia|Guinees biggetje]]'' (Guinean piglet) or ''cavia'' (or in some dialects, {{lang|nl|Spaanse rat}}); and in Portuguese, it is variously referred to as ''[[wikt:pt:cobaia|cobaia]]'', from the [[Tupian languages|Tupi]] word, or as {{lang|pt|porquinho da Índia}} (little Indian pig). This association with pigs is not universal among European languages; for example, the common word in Spanish is ''[[wikt:es:conejillo de Indias|conejillo de Indias]]'' (little rabbit of the Indies).<ref name="diccionario" />

The Chinese refer to the animal as {{lang|zh|豚鼠}} (''túnshǔ'', "pig mouse"), and sometimes as {{lang|zh|荷蘭豬}} (''hélánzhū'', 'Netherlands pig') or {{lang|zh|天竺鼠}} (''tiānzhúshǔ'', "Indian mouse"). The Japanese word for guinea pig is {{lang|ja|モルモット}} ({{Transliteration|ja|morumotto}}), which derives from the name of another mountain-dwelling rodent, the [[marmot]]. This word is how the guinea pigs were called by Dutch traders, who first brought them to [[Nagasaki]] in 1843. The other, and less common, Japanese word for guinea pig, using kanji, is 天竺鼠 (てんじくねずみ or {{Transliteration|ja|tenjiku-nezumi}}), which translates as "India rat".<ref>{{Cite web |title=tenjiku-nezumi – Meaning in Japanese {{!}} 天竺鼠 – Names of Animals in Japanese |url=https://animals.japanesewithanime.com/animals/tenjikunezumi |access-date=2018-09-15 |website=animals.japanesewithanime.com |language=en-us}}</ref>

==Biology==
{{Main|List of guinea pig breeds}}

[[File:Nibbles and strips 2.jpg|thumb|[[Parti-colored]] [[Abyssinian guinea pig]]s]]

Guinea pigs are relatively large for rodents. In pet breeds, adults typically weigh between {{convert|700|and|1200|g|lb|abbr=on}} and measure between {{convert|20|and|25|cm|in|round=0.5|abbr=on}} in length.{{sfn|Vanderlip|2003|p=13}} Some livestock breeds weigh {{Convert|3|kg|lb|abbr=on}} when full grown.<ref name="yamamoto2">{{Cite book |last=Yamamoto |first=Dorothy |title=Guinea Pig |publisher=Reaktion Books |year=2015 |isbn=978-1-78023-467-0 |location=London |chapter=Section 4: On The Menu |chapter-url=https://books.google.com/books?id=ooGiCgAAQBAJ&q=breeding+program+guinea+pig&pg=PT81}}</ref> Pet breeds live an average of four to five years but may live as long as eight years.{{sfn|Richardson|2000|pages=132–133}} According to ''[[Guinness World Records]]'', {{As of|2006||lc=y}}, the longest-lived guinea pig was 14&nbsp;years, 10&nbsp;months, and 2 weeks old.<ref>{{Cite book |title=Guinness Book of World Records |publisher=Guinness World Records Ltd. |year=2006 |isbn=978-1-904994-02-2 |editor-last=Glenday |editor-first=Craig |page=[https://archive.org/details/guinnessworldrec00glen/page/60 60] |title-link=Guinness Book of World Records }}</ref> Most guinea pigs have fur, but one laboratory breed adopted by some pet owners, the [[skinny pig]], is mostly furless. In contrast, several breeds have long fur, such as the [[Peruvian guinea pig|Peruvian]], the [[Silkie guinea pig|Silkie]], and the [[Texel Guinea Pig|Texel]]. They have four front teeth and small back teeth. Their front teeth grow continuously, so guinea pigs chew on materials such as wood to wear them down to prevent them from becoming too long.<ref>{{cite book|last=Petrylak |first=Ashley |date=2009|title=Guinea Pigs (Great Pets)|url=|publisher=Cavendish Square Publishing|page=13|isbn=978-0-7614-4148-9}}</ref> In the 1990s, a minority scientific opinion emerged proposing that [[caviomorpha|caviomorphs]] such as guinea pigs, [[chinchilla]]s, and [[Octodon|degu]]s are not actually rodents, and should be [[Taxonomy (biology)|reclassified]] as a separate [[order (biology)|order]] of mammals (similar to the rodent-like [[lagomorpha|lagomorphs]] which includes rabbits and hares).<ref>{{cite journal|last1 = Graur|first1 = D.|title = Is the Guinea-Pig a Rodent?|year = 1991|journal = [[Nature (journal)|Nature]]|volume = 351|pages = 649–652|doi = 10.1038/351649a0|last2 = Hide|first2 = Winston A.|last3 = Li|first3 = Wen-Hsiung|pmid = 2052090|issue = 6328|display-authors = 1|bibcode = 1991Natur.351..649G|s2cid = 4344039}}</ref><ref>{{cite journal|last1 = D'Erchia|first1 = A.|title = The Guinea Pig is Not a Rodent|year = 1996|journal = [[Nature (journal)|Nature]]|volume = 381|pages = 597–600|doi = 10.1038/381597a0|last2 = Gissi|first2 = Carmela|last3 = Pesole|first3 = Graziano|last4 = Saccone|first4 = Cecilia|last5 = Arnason|first5 = Ulfur|pmid = 8637593|issue = 6583|display-authors = 1|bibcode = 1996Natur.381..597D|s2cid = 4336262}}</ref><ref name="rodent">{{Cite journal |title=Is the guinea-pig (''Cavia porcellus'') a rodent? |journal=Comparative Biochemistry and Physiology Part B: Comparative Biochemistry |volume=107 |issue=2 |date=February 1994 |pages=179–182 |doi=10.1016/0305-0491(94)90037-X |last1=Noguchi |first1=Tomoo |last2=Fujiwara |first2=Satoko |last3=Hayashi |first3=Sucko |last4=Sakuraba |first4=Haruhiko}}</ref> Subsequent research using [[Sampling (statistics)|wider sampling]] restored the consensus among mammalian biologists regarding the current classification of rodents, including guinea pigs, as [[monophyly|monophyletic]].<ref>{{Cite book|last1 = Carleton|first1 = Michael D.|last2 = Musser|first2 = Guy G.|contribution = Order Rodentia|editor1-last = Wilson|editor1-first = Don E.|title = Mammal Species of the World|edition = 3rd|year = 2005|volume = 2|page = 745|publisher = Johns Hopkins University Press|isbn = 978-0-8018-8221-0|editor2-last = Reeder|editor2-first = DeeAnn M.}}</ref><ref>{{Cite journal |last1=Huchon |first1=Dorothée |last2=Chevret |first2=Pascale |last3=Jordan |first3=Ursula |last4=Kilpatrick |first4=C. William |last5=Ranwez |first5=Vincent |last6=Jenkins |first6=Paulina D. |last7=Brosius |first7=Jürgen |last8=Schmitz |first8=Jürgen |date=May 1, 2007 |title=Multiple molecular evidences for a living mammalian fossil |journal=[[Proceedings of the National Academy of Sciences|PNAS]] |volume=104 |issue=18 |pages=7495–7499 |bibcode=2007PNAS..104.7495H |doi=10.1073/pnas.0701289104 |pmc=1863447 |pmid=17452635|doi-access=free }}</ref>

Wild cavies are found on grassy plains and occupy an [[ecological niche]] similar to that of [[cattle]]. They are social animals, living in the wild in small groups ("[[herd]]s") that consist of several females ("sows"), a male ("boar"), and their young ("pups" not "piglets", a break with the preceding [[pig|porcine]] nomenclature). Herds of animals move together, eating grass or other vegetation, yet do not store food.{{sfn|Wagner|Manning|1976|pp=31–32}} While they do not [[burrow]] themselves or build nests, they frequently seek shelter in the burrows of other animals, as well as in crevices and tunnels formed by vegetation.{{sfn|Wagner|Manning|1976|pp=31–32}} They are [[crepuscular]] and tend to be most active during dawn and dusk when it is harder for predators to spot them.{{sfn|Terril|Clemons|1998|p=6}}<!-- Male vs. female -->

Male and female guinea pigs do not significantly [[sexual dimorphism|differ in appearance]] apart from general size. The position of the [[anus]] is very close to the [[genitals]] in both sexes. [[Sexing|Sexing animals]] at a young age must be done by someone trained in the differences. Female genitals are distinguished by a Y-shaped configuration formed from a [[Vulva|vulvar flap]]. While male genitals may look similar, with the [[penis]] and anus forming a similar shape, the penis will protrude if pressure is applied to the surrounding hair anterior to the genital region.{{sfn|Richardson|2000|pages=14, 17}} The male's [[testes]] may also be visible externally from [[scrotal]] swelling.

[[File:Guinea pigs - Japanese petting zoo - 2018 6 26.webm|thumb|Guinea pigs in a petting zoo]]

===Behavior===
[[File:Three guinea pigs (Cavia porcellus) at Keswick Public Library.jpg|thumb|Guinea pigs "social groom" each other.|alt=|left]]

Guinea pigs can learn complex paths to food and can accurately remember a learned path for months. Their most robust [[problem-solving]] strategy is motion.<ref>{{cite journal|last = Charters|first = Jessie Blount Allen|title = The associative processes of the guinea pig: A study of the psychical development of an animal with a nervous system well medullated at birth|journal = Journal of Comparative Neurology and Psychology|volume = XIV|issue = 4|pages = 300–337|date=July 1904|url = https://books.google.com/books?id=dWcKAAAAMAAJ&q=guinea+pigs&pg=RA2-PA300|access-date = 2006-12-27|doi=10.1002/cne.920140402| hdl=2027/mdp.39015031094876 }}</ref> While guinea pigs can jump small obstacles, they cannot jump very high. Most of them are poor climbers and are not particularly agile. They startle easily, and when they sense danger, they either freeze in place for long periods or run for cover with rapid, darting motions.{{sfn|Terril|Clemons|1998|p=6}} Larger groups of startled guinea pigs "[[stampede]]", running in haphazard directions as a means of confusing predators.{{sfn|Wagner|Manning|1976|p=34}} When happily excited, guinea pigs may (often repeatedly) perform little hops in the air (a movement known as "popcorning"), analogous to the [[ferret]]'s [[weasel war dance|war dance]]<ref>{{cite web|title = Guinea Pigs|publisher = Canadian Federation of Humane Societies|url = http://cfhs.ca/athome/guinea_pigs|access-date = 2007-03-21|archive-url = https://web.archive.org/web/20070402223933/http://cfhs.ca/athome/guinea_pigs/|archive-date = 2007-04-02}}</ref> or rabbit happy hops (binkies). Guinea pigs are also good swimmers,<ref name="harkness">{{cite book|last1 = Harkness|first1 = John E.|last2 = Wagner|first2 = Joseph E.|title = The Biology and Medicine of Rabbits and Rodents|publisher = Williams & Wilkins|year = 1995|pages = 30–39|isbn = 978-0-683-03919-1}}</ref> although they do not like being wet and infrequently need bathing.

Like many rodents, guinea pigs sometimes participate in [[social grooming]] and regularly self-groom.{{sfn|Vanderlip|2003|p=79}} A milky-white substance is secreted from their eyes and rubbed into the hair during the grooming process.{{sfn|Richardson|2000|page=72}} Groups of boars often chew each other's hair, but this is a method of establishing hierarchy within a group, rather than a social gesture.<ref name="harkness" /> Dominance is also established through biting (especially of the ears), [[Goose bumps|piloerection]], aggressive noises, head thrusts, and leaping attacks.{{sfn|Wagner|Manning|1976|p=38}} Non-sexual simulated [[wikt:mount#Verb|mounting]] for dominance is also common among same-sex groups.{{citation needed|date=November 2020}}

Guinea pig eyesight is not as good as that of a human in terms of distance and color, but they have a wider angle of vision (about 340°) and see in partial color ([[dichromacy]]). They have well-developed senses of hearing, [[olfaction|smell]], and touch.{{sfn|Wagner|Manning|1976|pp=32–33}}{{sfn|Vanderlip|2003|p=14}}

Guinea pigs have developed a different [[biological rhythm]] from their wild counterparts and have longer periods of activity followed by short sleep in between.{{sfn|Terril|Clemons|1998|p=6}} Activity is scattered randomly throughout the day; aside from an avoidance of intense light, no regular [[circadian rhythm|circadian patterns]] are apparent.{{sfn|Terril|Clemons|1998|p=6}}[[File:Cat with guinea pigs.jpg|alt=|thumb|300x300px|Although this cat has accepted these guinea pigs, the success of interspecies interaction depends on the individual animals.]]Guinea pigs do not generally thrive when housed with other species. Larger animals may regard guinea pigs as [[predation|prey]], though some [[dog]]s and [[cat]]s can be trained to accept them.<ref name="behrend">{{cite book|last=Behrend|first=Katrin|url=https://archive.org/details/guineapigseveryt00behr/page/22|title=Guinea Pigs: A Complete Pet Owner's Manual|publisher=Barron's|year=1998|isbn=978-0-7641-0670-5|pages=[https://archive.org/details/guineapigseveryt00behr/page/22 22–23]}}</ref> Opinion is divided over the cohousing of guinea pigs and [[domestic rabbit|rabbit]]s. Some published sources say that guinea pigs and rabbits complement each other well when sharing a cage.<ref name="behrend" />{{sfn|Vanderlip|2003|p=20}} However, rabbits have different nutritional requirements; as [[Lagomorpha|lagomorphs]], they synthesize their own [[vitamin C]], so the two species will not thrive if fed the same food when housed together.{{sfn|Terril|Clemons|1998|p=41}} Rabbits may also harbor diseases (such as respiratory infections from ''[[Bordetella]]'' and ''[[Pasteurella]]''), to which guinea pigs are susceptible.{{sfn|Wagner|Manning|1976|pp=126–128}} Housing guinea pigs with other rodents such as [[gerbil]]s and [[hamster]]s may increase instances of respiratory and other infections,{{sfn|Wagner|Manning|1976|p=122}} and such rodents may act aggressively toward guinea pigs.{{sfn|Vanderlip|2003|p=19}}

===Vocalization===
Vocalization is the primary means of communication between members of the species.{{sfn|Terril|Clemons|1998|p=7}} These are the most common sounds made by the guinea pig:{{sfn|Terril|Clemons|1998|pp=7–8}}
*A "''wheek''" is a loud noise, the name of which is [[onomatopoeia|onomatopoeic]], also known as a whistle. An expression of general excitement may occur in response to the presence of its owner or feeding. It is sometimes used to find other guinea pigs if they are running. If a guinea pig is lost, it may wheek for assistance. {{Audio|Guinea Pig Feeding Wheek.ogg|listen}}
*A bubbling or purring sound is made when the guinea pig enjoys itself, such as when petting and holding. It may also make this sound when grooming, crawling around to investigate a new place, or when given food. {{Audio|Guinea Pig Happy.ogg|listen}}
*A rumbling sound is normally related to dominance within a group, though it can also come as a response to being scared or angry. In the case of being scared, the rumble often sounds higher, and the body vibrates shortly. While courting, a male usually purrs deeply, swaying and circling the female{{sfn|Wagner|Manning|1976|p=39}} in a behavior called ''rumblestrutting''. A low rumble while walking away reluctantly shows [[Passive aggressive|passive]] resistance. {{Audio|Guinea Pig Keep Away.ogg|listen}}
*Chutting and whining are sounds made in pursuit situations by the pursuer and pursuee, respectively. {{Audio|Guinea Pig Angry.ogg|listen}}
*A chattering sound is made by rapidly gnashing the [[tooth|teeth]], and is generally a sign of warning. Guinea pigs tend to raise their heads when making this sound.
*Squealing or shrieking is a high-pitched sound of discontent in response to pain or danger. {{Audio|Guinea Pig In Distress.ogg|listen}}
*Chirping, a less common sound likened to [[bird vocalization|bird song]], seems to be related to stress or discomfort or when a baby guinea pig wants to be fed. Very rarely, the chirping will last for several minutes. {{Audio|Guinea Pig Chirping.ogg|listen}}

=== Reproduction ===
[[File:Fat Adie pictures 001.jpg|thumb|right|[[Pregnant]] sow one week before delivering three pups]]

Males (boars) reach [[sexual maturity]] in 3–5 weeks. Similarly, females (sows) can be fertile as early as four weeks old and carry litters before becoming fully grown adults.{{sfn|Richardson|2000|pages=15–16}} A sow can breed year-round (with spring being the peak). A sow can have as many as five litters in a year, but six is theoretically possible<!-- 360/60 -->.<ref name="walker" /> Unlike the offspring of most [[rodents]], which are [[altricial]] at birth, newborn cavy pups are [[Precociality|precocial]], and are well-developed with hair, teeth, claws, and partial eyesight.<ref name="harkness" /> The pups are immediately mobile and capable of eating solid food, though they continue to [[breastfeeding|suckle]]. Sows can once again become pregnant 6–48 hours after giving birth, but it is not healthy for a female to be constantly pregnant.{{sfn|Richardson|2000|pages=17–18}}

The [[gestation]] period lasts from {{convert|59|-|72|day|month}}, with an average of {{convert|63|-|68|day|month}}.<ref name="nrc" /> Because of the long gestation period and the large size of the pups, pregnant sows may become large and [[eggplant]]-shaped, although the change in size and shape varies depending upon the size of the litter. [[Litter (animal)|Litter]] size ranges from one to six, with three being the average;{{sfn|Richardson|2000|pages=}} the largest recorded litter size is 9.<ref>{{Cite web |title=Largest litter of guinea pigs |url=https://www.guinnessworldrecords.com/world-records/69437-largest-guinea-pig-litter |access-date=2021-03-15 |website=Guinness World Records |language=en-GB}}</ref> The guinea pig mother only has two nipples, but she can readily raise the more average-sized litters of 2 to 4 pups.<ref name="Merck Veterinarian Manual, 2016">[http://www.merckvetmanual.com/all-other-pets/guinea-pigs/breeding-and-reproduction-of-guinea-pigs Breeding and Reproduction of Guinea Pigs], Merck Veterinarian Manual, Katherine E. Quesenberry, DVM, MPH, DABVP (Avian); Kenneth R. Boschert, DVM, DACLAM, 2016.</ref><ref name="Harkness and Wagner's Biology and Medicine of Rabbits and Rodents, 2010">[https://books.google.com/books?id=SFSXqsWvsMQC&dq=%22despite+having+only+two+nipples%2C+guinea+pigs+can+raise+litters+of+3%2C+4%2C+and+more+young%22&pg=PA55 Harkness and Wagner's Biology and Medicine of Rabbits and Rodents, 5th Edition], John E. Harkness, Patricia V. Turner, Susan VandeWoude, Colette L. Wheler, Iowa, USA: Wiley & Sons, "Ch. 2 Biology and Husbandry," 2010.</ref> In smaller litters, difficulties may occur during [[Childbirth|labour]] due to oversized pups. Large litters result in higher incidences of [[stillbirth]], but because the pups are delivered at an advanced stage of development, lack of access to the mother's milk has little effect on the mortality rate of newborns.{{sfn|Wagner|Manning|1976|p=88}}[[File:Guinea baby 1.jpg|thumb|Guinea pig pup at eight hours old|alt=|left]]

Cohabitating females assist in mothering duties if [[Lactation|lactating]];<ref name="percy">{{cite book |last1=Percy |first1=Dean H. |title=Pathology of Laboratory Rodents and Rabbits |last2=Barthold |first2=Stephen W. |publisher=Iowa State University Press |year=2001 |isbn=978-0-8138-2551-9 |edition=2nd |pages=209–247}}</ref> guinea pigs practice [[Alloparenting|alloparental care]], in which a sow may adopt the pups of another. This might take place if the original parents die or are, for some reason, separated from them. This behavior is common and is seen in many other animal species, such as the elephant.<ref>{{cite journal |last1=Riedman |first1=Marianne L. |year=1982 |title=The Evolution of Alloparental Care in Mammals and Birds |journal=The Quarterly Review of Biology |volume=57 |issue=4 |pages=405–435 |doi=10.1086/412936 |s2cid=85378202}}</ref>

<!-- Complications -->[[pre-eclampsia|Toxemia of pregnancy]] (hypertension) is a common problem and kills many pregnant females. Signs of toxemia include anorexia (loss of appetite), [[Lethargy|lack of energy]], [[Salivation|excessive salivation]], a [[Bad breath|sweet or fruity breath odor]] due to [[ketone]]s, and [[seizure]]s in advanced cases.{{sfn|Richardson|2000|pages=20–21}} Pregnancy toxemia appears to be most common in hot climates.{{sfn|Richardson|2000|page=20}} Other serious complications during pregnancy can include a [[prolapse|prolapsed uterus]], [[hypocalcaemia]], and [[mastitis]].{{sfn|Richardson|2000|pages=25–29}}

Females that do not give birth may develop an irreversible fusing or calcified cartilage of the [[pubic symphysis]], a joint in the [[pelvis]], which may occur after six months of age.<ref name="nrc" />{{rp|72–73|date=November 2012}} If they become pregnant after this has happened, the birth canal may not widen sufficiently, which may lead to [[dystocia]] and death as they attempt to give birth.{{sfn|Richardson|2000|pages=25–26}}

== Husbandry ==

===Living environment===
[[File:Guinea pig 2011 01 10 12 58 15.jpg|Long haired guinea pig|thumb]]
Domestic guinea pigs generally live in [[cage]]s, although some owners of large numbers of cavies dedicate entire rooms to their pets.{{Citation needed|date=February 2021}} Wire mesh floors can cause injury and may be associated with an infection commonly known as [[bumblefoot (infection)|bumblefoot]] (ulcerative pododermatitis),{{sfn|Richardson|2000|pages=63–64}} so cages with solid bottoms, where the animal walks directly on the bedding, are typically used. Large cages allow for adequate running space and can be constructed from wire grid panels and plastic sheeting, a style known as C&C, or "cubes and coroplast".<ref name="orcutt">{{Cite web|last=Orcutt|first=Connie|date=April 1, 2016|title=Guinea pigs with room to move|url=https://podcasts.ufhealth.org/guinea-pigs-with-room-to-move/|access-date=2021-02-02|website=University of Florida Health}}</ref>

Red cedar ([[Eastern redcedar|Eastern]] or [[Western redcedar|Western]]) and [[pine]], both [[softwood]]s, were commonly used as bedding. Still, these materials are believed to contain harmful [[phenol]]s (aromatic hydrocarbons) and oils.{{sfn|Terril|Clemons|1998|p=34}} Bedding materials made from [[hardwood]]s (such as [[aspen]]), paper products, and [[Corncob|corn cobs]] are alternatives.{{sfn|Terril|Clemons|1998|p=34}} Guinea pigs tend to be messy; they often jump into their food bowls or kick bedding and feces into them, and their [[urine]] sometimes crystallizes on cage surfaces, making it difficult to remove.{{sfn|Vanderlip|2003|pp=44, 49}} After its cage has been cleaned, a guinea pig typically urinates and drags its lower body across the floor of the cage to [[Territory (animal)#Scent marking|mark its territory]].<ref name="nrc">{{cite book|last=National Resource Council|url=https://archive.org/details/rodents0000unse/page/72|title=Laboratory Animal Management: Rodents|publisher=National Academy Press|year=1996|isbn=978-0-309-04936-8|pages=[https://archive.org/details/rodents0000unse/page/72 72–73]}}</ref> Male guinea pigs may mark their territory in this way when they are put back into their cages after being taken out.{{citation needed|date=November 2020}}

Guinea pigs thrive in groups of two or more; groups of sows or groups of one or more sows and a neutered boar are common combinations, but boars can sometimes live together. Guinea pigs learn to recognize and bond with other individual guinea pigs, and tests show that a boar's [[neuroendocrine]] stress response to a strange environment is significantly lowered in the presence of a bonded female but not with unfamiliar females.<ref>{{cite journal|url = http://www.scielo.br/pdf/bjmbr/v37n6/4930.pdf | last1 = Cohn|first1 = D.W.H.|title = Female Novelty and the Courtship Behavior of Male Guinea Pigs|journal = Brazilian Journal of Medical and Biological Research|volume = 37|year = 2004|pages = 847–851|doi = 10.1590/S0100-879X2004000600010|pmid = 15264028|last2 = Tokumaru|first2 = RS|last3 = Ades|first3 = C|issue = 6|display-authors=1|doi-access = free}}</ref> Groups of boars may also get along, provided their cage has enough space, they are introduced at an early age, and no females are present.{{sfn|Vanderlip|2003|pp=33–34}} In Switzerland, where owning a single guinea pig is considered harmful to its well-being, keeping a guinea pig without a companion is illegal.<ref>{{cite web |last1=Maurisse |first1=Marie |date=17 August 2011 |title=En Suisse, les animaux domestiques doivent obligatoirement être en couple |url=http://blog.lefigaro.fr/suisse/2011/08/en-suisse-les-animaux-domestiques-doivent-etre-en-couple.html}}</ref> There is a service to rent guinea pigs, to temporarily replace a dead cage-mate.<ref>{{Cite web|title=Rent-A-Guinea Pig Service Takes Off in Switzerland|url=https://abcnews.go.com/International/rent-guinea-pig-service-takes-off-switzerland/story?id=14573692|access-date=2021-02-03|website=ABC News|language=en}}</ref> Sweden has similar laws against keeping a guinea pig by itself.<ref>{{Cite journal|last=Mihai|first=Andrei|date=January 29, 2021|title=Why it's illegal to own one guinea pig in Switzerland|url=https://www.zmescience.com/ecology/animals-ecology/guinea-pig-switzerland/|journal=ZME Science|volume=Animals, Feature Post|pages=|quote=Sweden has similar legislation in place and several other countries have sensible laws protecting social animals.|via=}}</ref>

=== Diet ===
{{Further|Cecotrope}}
[[File:Cavy eating grass.jpg|thumb|right|A silver [[Agouti (coloration)|agouti]] guinea pig eating grass, the staple of the diet, which is often replaced with [[hay]].|276x276px]]

The guinea pig's natural diet is [[grass]]; their [[Molar (tooth)|molars]] are particularly suited for grinding plant matter and grow continuously throughout their life.{{sfn|Wagner|Manning|1976|p=228}} Most mammals that graze are large and have a long digestive tract. Guinea pigs have much longer [[Colon (anatomy)|colons]] than most rodents.

Easily digestible food is processed in the gastrointestinal tract and expelled as regular feces. But to get nutrients out of hard-to-digest fiber, guinea pigs ferment fiber in the cecum (in the GI tract) and then expel the contents as [[cecotrope]]s, which are reingested ([[cecotrope|cecotrophy]]). The cecotropes are then absorbed in the small intestine to utilize the nutrients.{{sfn|Richardson|2000|pages=50–51}}{{sfn|Terril|Clemons|1998|p=41}}{{sfn|Wagner|Manning|1976|p=236}} The [[cecotrope]]s are eaten directly from the anus unless the guinea pig is pregnant or obese.{{sfn|Terril|Clemons|1998|p=41}} They share this behavior with [[lagomorpha|lagomorphs]] (rabbits, hares, pikas) and some other animals.

In geriatric boars or sows (rarely in young ones), the muscles which allow the cecotropes to be expelled from the anus can become weak. This creates a condition known as [[fecal impaction]], which prevents the animal from redigesting cecotropes even though harder pellets may pass through the impacted mass.{{sfn|Richardson|2000|page=52}} The condition may be temporarily alleviated by a human carefully removing the impacted feces from the anus.{{citation needed|date=November 2020}}

Guinea pigs benefit from a diet of fresh [[grass hay]], such as [[Timothy-grass|timothy hay]], in addition to [[food pellets]], which are often based on timothy hay. [[Alfalfa]] hay is also a popular food choice, and most guinea pigs will eat large amounts of alfalfa when offered it,{{sfn|Morales|1995|page=8}}{{sfn|Wagner|Manning|1976|p=32}} though some controversy exists over offering alfalfa to adult guinea pigs. Some pet owners and veterinary organizations have advised that, as a [[legume]] rather than a grass hay, alfalfa consumed in large amounts may lead to [[obesity]], as well as [[bladder stone (animal)|bladder stones]] from the excess [[calcium]] in all animals except for pregnant and very young guinea pigs.<ref>{{cite web |title=Guinea Pig Diet |url=http://mgpr.org/newsite/GP_Info/Guinea%20Pig%20Diet.htm |website=Metropolitan Guinea Pig Rescue |access-date=13 March 2021}}</ref> However, published scientific sources mention alfalfa as a food source that can replenish protein, [[amino acid]]s, and fiber.<ref>{{cite book|author = Institute for Laboratory Animal Research|title = Nutrient Requirements of Laboratory Animals|edition = 4th|publisher = National Academies Press|year = 1995|page = 106|url = http://books.nap.edu/openbook.php?record_id=4758&page=106|isbn = 978-0-309-05126-2|author-link = Institute for Laboratory Animal Research}}</ref>{{sfn|Wagner|Manning|1976|p=236}}{{sfn|Terril|Clemons|1998|p=39}}

Like humans, but unlike most other [[mammal]]s, guinea pigs cannot synthesize vitamin C and must obtain this vital [[nutrient]] from food. If guinea pigs do not ingest enough vitamin C, they can suffer from potentially fatal [[scurvy]]. They require about 10&nbsp;mg of vitamin C daily (20&nbsp;mg if pregnant), which can be obtained through fresh, raw fruits and vegetables (such as broccoli, apple, cabbage, carrot, celery, and spinach) or dietary supplements or by eating fresh [[Animal feed#Fodder|pellets]] designed for guinea pigs, if they have been handled properly.{{sfn|Richardson|2000|page=92}} Healthy diets for guinea pigs require a complex balance of calcium, [[magnesium]], [[phosphorus]], [[potassium]], and [[hydrogen ion]]s; but adequate amounts of vitamins [[Vitamin A|A]], [[Vitamin D|D]], and [[Vitamin E|E]] are also necessary.{{sfn|Terril|Clemons|1998|p=40}}

Poor diets for guinea pigs have been associated with [[muscular dystrophy]], [[metastatic calcification]], difficulties with pregnancy, [[vitamin deficiencies]], and teeth problems.{{sfn|Wagner|Manning|1976|pp=237–257}}{{sfn|Richardson|2000|pages=89–91}} Guinea pigs tend to be fickle eaters when it comes to fresh fruits and vegetables after having learned early in life what is and is not appropriate to consume. Their eating habits may be difficult to change after maturity.{{sfn|Wagner|Manning|1976|p=236}}{{sfn|Richardson|2000|pages=88–89}} They do not respond well to sudden changes in their diet, and they may stop eating and starve rather than accept new food types.<ref name="harkness" /> A constant supply of hay is generally recommended, as guinea pigs feed continuously and may develop bad habits if food is not present, such as chewing on their hair.{{sfn|Richardson|2000|page=89}} Being rodents, as their teeth grow constantly (as do their nails, like humans), they routinely [[wikt:gnaw|gnaw]] on things, lest their teeth become too large for their jaw (a common problem in [[rodent]]s).{{citation needed|date=November 2020}} Guinea pigs chew on cloth, paper, plastic, and rubber if available. Guinea pig owners may "Guinea Pig proof" their household, especially if they are free to roam, to avoid any destruction or harm to the guinea pig itself.<ref>{{Cite web |title=How To Guinea Pig Proof Your Room {{!}} First Steps With A Guinea Pig |url=https://www.omlet.co.uk/guide/guinea_pigs/first_steps_with_a_guinea_pig/room_proofing/ |access-date=2024-01-22 |website=www.omlet.co.uk |language=en-gb}}</ref>

Some plants are poisonous to guinea pigs, including [[bracken]], [[Bryonia|bryony]], [[ranunculus|buttercup]], [[sinapis arvensis|charlock]], [[atropa belladonna|deadly nightshade]], [[digitalis|foxglove]], [[hellebore]], [[conium|hemlock]], [[lily of the valley]], [[Anthemis cotula|mayweed]], [[aconitum|monkshood]], [[privet]], [[Senecio|ragwort]], [[rhubarb]], [[veronica arvensis|speedwell]], toadflax (both ''[[Linaria vulgaris]]'' and ''[[Linaria dalmatica]]''), and [[vallisneria americana|wild celery]].{{sfn|Richardson|2000|page=93}} Additionally, any plant which grows from a [[bulb]] (e.g., [[tulip]] or [[onion]]) is normally considered poisonous,{{sfn|Richardson|2000|page=3}} as well as ivy and oak tree leaves.

{{clear left}}

=== Health problems ===
Common ailments in domestic guinea pigs include [[Lower respiratory tract infection|respiratory tract infections]], [[diarrhea]], [[scurvy]] (vitamin C deficiency, typically characterized by sluggishness), [[abscess]]es due to infection (often in the neck, due to hay embedded in the throat, or from external scratches), and infections by [[louse|lice]], [[mite]]s, or [[fungus]].{{sfn|Richardson|2000|loc=ch. 1, 4, 5, 9}}

[[Mange mite]]s (''Trixacarus caviae'') are a common cause of hair loss, and other symptoms may also include excessive scratching, unusually aggressive behavior when touched (due to pain), and, in some instances, seizures.{{sfn|Richardson|2000|pages=3–4}} Guinea pigs may also suffer from "running lice" (''Gliricola porcelli''), a small, white insect that can be seen moving through the hair; their eggs, which appear as black or white specks attached to the hair, are sometimes referred to as "static lice". Other causes of hair loss can be hormonal upsets caused by underlying medical conditions such as [[ovarian cyst]]s.{{sfn|Richardson|2000|page=55}}

[[File:mvc-872s.jpg|thumb|A [[parti-colored]] guinea pig suffering from [[torticollis]], or wry neck]]

Foreign bodies, especially tiny pieces of hay or straw, can become lodged in the eyes of guinea pigs, resulting in excessive blinking, tearing, and, in some cases, an opaque film over the eye due to [[corneal ulcers in animals|corneal ulcer]].{{sfn|Richardson|2000|pages=69–70}} Hay or straw dust can also cause [[sneeze|sneezing]]. While it is normal for guinea pigs to sneeze periodically, frequent sneezing may be a symptom of [[pneumonia (non-human)|pneumonia]], especially in response to atmospheric changes. Pneumonia may also be accompanied by [[torticollis]] and can be fatal.{{sfn|Richardson|2000|pages=45–48}}

Because the guinea pig has a stout, compact body, it more easily tolerates excessive cold than excessive heat.{{sfn|Wagner|Manning|1976|p=6}} Its normal [[thermoregulation|body temperature]] is {{convert|101|–|104|F|C|order=flip}},{{sfn|Terril|Clemons|1998|p=19}} so its ideal ambient air temperature range is similar to a human's, about {{convert|65|–|75|F|C|order=flip}}.{{sfn|Wagner|Manning|1976|p=6}} Consistent ambient temperatures in excess of {{convert|90|F|C|order=flip}} have been linked to [[hyperthermia]] and death, especially among pregnant sows.{{sfn|Wagner|Manning|1976|p=6}} Guinea pigs are not well suited to environments that feature wind or frequent drafts,{{sfn|Terril|Clemons|1998|p=37}} and respond poorly to extremes of [[humidity]] outside of the range of 30–70%.{{sfn|Terril|Clemons|1998|p=36}}

Guinea pigs are [[Predation|prey]] animals whose survival instinct is to mask pain and signs of illness, and many times, health problems may not be apparent until a condition is severe or in its advanced stages. Treatment of disease is made more difficult by the extreme sensitivity guinea pigs have to most [[antibiotic]]s, including [[penicillin]], which kill off the [[gut flora|intestinal flora]] and quickly bring on episodes of diarrhea and in some cases, death.{{sfn|Wagner|Manning|1976|p=229}}{{sfn|Richardson|2000|pages=105–106}}

Similar to the inherited [[genetic disorder|genetic diseases]] of other breeds of animals (such as [[Hip dysplasia (canine)|hip dysplasia]] in canines), some genetic abnormalities of guinea pigs have been reported. Most commonly, the [[roan (color)#Roan guinea pigs|roan]] coloration of [[Abyssinian guinea pig|Abyssinian]] guinea pigs is associated with [[congenital disorder|congenital]] eye disorders and problems with the digestive system.{{sfn|Richardson|2000|page=69}} Other genetic disorders include "waltzing disease" (deafness coupled with a tendency to run in circles), palsy, and [[tremor]] conditions.<ref name=robinson>{{Cite book|last = Robinson|first = Roy|contribution = The Guinea Pig, ''Cavia Porcellus''|editor-last = King|editor-first = Robert C|title = Handbook of Genetics|volume = 4|year = 1974|pages = 275–307|publisher = Plenum|isbn = 978-0-306-37614-6}}</ref>

== 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= https://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 |article-number=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>[https://web.archive.org/web/20051113164634/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".

== Metaphorical usage ==
In [[English language|English]], the term "guinea pig" is commonly used as a metaphor for a subject of scientific experimentation, or in modern times a subject of any experiment or test. This usage dates back to the early 20th century: the earliest examples cited by the ''[[Oxford English Dictionary]]'' date from 1913 and 1920.<ref>{{OED|guinea pig}}</ref> In 1933, [[Consumers' Research]] founders [[F. J. Schlink]] and [[Arthur Kallet]] wrote a book entitled ''[[100,000,000 Guinea Pigs]]'', extending the metaphor to consumer society.<ref>{{cite book|last1 = Kallet|first1 = Arthur|last2 = Schlink|first2 = F. J.|title = 100,000,000 Guinea Pigs: Dangers in Everyday Foods, Drugs, and Cosmetics|publisher = Vanguard Press|year = 1933|isbn = 978-0-405-08025-8}}</ref> The book became a national bestseller in the United States, thus further popularizing the term, and spurred the growth of the [[consumer protection]] movement.<ref>{{Cite book|last = McGovern|first = Charles|contribution = Consumption|editor-last = Whitfield|editor-first = Stephen J.|title = A Companion to 20th-Century America|year = 2004|page = [https://archive.org/details/companionto20thc0000unse/page/346 346]|publisher = Blackwell|isbn = 978-0-631-21100-6|url = https://archive.org/details/companionto20thc0000unse/page/346}}</ref> During [[World War II]], the [[Guinea Pig Club]] was established at [[Queen Victoria Hospital]], [[East Grinstead]], Sussex, England, as a social club and mutual support network for the patients of [[Plastic surgery|plastic surgeon]] [[Archibald McIndoe]], who were undergoing previously untested reconstruction procedures.<ref>{{cite book |first=Edward |last=Bishop |title=McIndoe's Army: the story of the Guinea Pig Club and its indomitable members |place=London |publisher=Grub Street |edition=revised |year=2004 |orig-date=2001 |isbn=1-904943-02-0 |pages=2–4 }}</ref> The negative connotation of the term was later employed in the novel ''The Guinea Pigs'' (1970) by [[Czechs|Czech]] author [[Ludvík Vaculík]] as an allegory for [[Soviet Union|Soviet]] [[totalitarianism]].<ref>{{cite book|last = Vaculík|first = Ludvík|title = The Guinea Pigs|publisher = Third Press|year = 1973|isbn = 978-0-89388-060-6|url = https://archive.org/details/guineapigsnovel00vacu}}</ref>

==See also==
{{Portal|Mammals}}
*[[Rodents as pets]]
*[[Peter Gurney]], guinea pig rights advocate
*[[Save the Newchurch Guinea Pigs]], against breeding for animal research
*[[Kurloff cell]], special cells found in the blood and organs of guinea pigs
{{clear}}

==References==
{{Reflist|30em}}

==Sources==
<!-- *{{cite book|ref=Archetti|last = Archetti|first = Eduardo|title = Guinea-Pigs: Food, Symbol and Conflict of Knowledge in Ecuador|url=https://archive.org/details/guineapigsfoodsy0000arch|url-access=registration|year = 1997 |publisher = Berg|isbn = 1-85973-114-7}}-->
*{{cite book|last=Petrylak |first=Ashley |date=2009|title=Guinea Pigs (Great Pets)|url=|publisher=Cavendish Square Publishing|isbn=978-0-7614-4148-9}}
*{{cite book|last = Morales|first = Edmundo|title = The Guinea Pig: Healing, Food, and Ritual in the Andes|publisher = University of Arizona Press|year = 1995|isbn = 978-0-8165-1558-5}}
*{{cite book|last = Richardson|first = V.C.G.|title = Diseases of Domestic Guinea Pigs |edition = 2nd|publisher = Blackwell|year = 2000 |isbn = 978-0-632-05209-7}}
*{{cite book|last1 = Terril|first1 = Lizabeth A.|last2 = Clemons|first2 = Donna J.|title = The Laboratory Guinea Pig|publisher = CRC Press|year = 1998|isbn = 978-0-8493-2564-9}}
*{{cite book|last = Vanderlip|first = Sharon|title = The Guinea Pig Handbook|publisher = Barron's|year = 2003|isbn = 978-0-7641-2288-0}}
*{{cite book|last1 = Wagner|first1 = Joseph E.|last2 = Manning|first2 = Patrick J|title = The Biology of the Guinea Pig|year = 1976|publisher = Academic Press|isbn = 978-0-12-730050-4|url=https://books.google.com/books?id=DcTaAgAAQBAJ}}

==External links==
{{sister project links|wikt=guinea pig|species=Cavia porcellus|c=Category:Cavia porcellus|b=Animal Care/Guinea pig|n=no|s=no|v=no|voy=no|d=Q79803|q=no}}
* [http://acbaonline.com/ American Cavy Breeders' Association (ACBA)]
*View the [http://www.ensembl.org/Cavia_porcellus/Info/Index/ guinea pig genome] on [[Ensembl]]

{{Caviidae nav}}
{{Meat}}
{{Animal domestication}}
{{portalbar|Mammals|Animals|Biology}}
{{Taxonbar|from=Q79803}}
{{Authority control}}

{{DEFAULTSORT:Guinea Pig}}
[[Category:Guinea pigs| ]]
[[Category:Cavies]]
[[Category:Domesticated animals]]
[[Category:Rodents of South America]]
[[Category:Fauna of the Andes]]
[[Category:Mammals of Peru]]
[[Category:Mammals of Bolivia]]
[[Category:Mammals of Colombia]]
[[Category:Bolivian cuisine]]
[[Category:Ecuadorian cuisine]]
[[Category:Peruvian cuisine]]
[[Category:Mammals described in 1758]]
[[Category:Animal taxa named by Carl Linnaeus]]
[[Category:Animal models]]
[[Category:Pleistocene rodents]]
[[Category:Quaternary mammals of South America]]
[[Category:Extant Pleistocene first appearances]]