Editing Guinea pig (section)

=== 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".