THE GUINEA PIG 6 



dominating colors with distinctly marked areas of white. (6) 

 Brindle, a mixture of dark and tan without distinctly outlined patches. 

 In its native habitat the guinea pig makes its nest in the tall grass 

 and eats seeds, grass, and vegetables. In the homes of the natives in 

 Peru the guinea pig shares the one-room house with the family and 

 runs about freety, nesting in corners or under stone benches used by 

 the natives for tables and seats. Table scraps and vegetables from the 

 garden furnish food. 



Uses 



Just when guinea pigs were first used for scientific purposes is not 

 known, but previous to 1870 the only use for guinea pigs in Europe 

 and in the United States seems to have been as pets. Many guinea 

 pigs were used in the period from 1870 to 1890, when Koch, Roux, 

 Pasteur, and others were making their discoveries of the bacterial 

 causes of disease and of agents for combating them. Since this period, 

 the guinea pig has been used extensively for a wide variety of experi- 

 mental purposes, including inoculation with pathogenic organisms for 

 the purpose of studying the symptoms of a disease, the pathological 

 changes involved, and the effects of certain drugs which may be used 

 as curative agents; the standardization of vaccines, serums, and anti- 

 toxins; genetic experiments; vitamin studies; observations on the 

 estrous cycle of animals, now a regular clinical procedure; and many 

 others. Many food-manufacturing companies maintain colonies of 

 guinea pigs for standardizing the vitamin content of their products. 

 Guinea pigs weighing 250 grams, or about one-half pound, are desired 

 for many experimental purposes. They reach this weight at from 

 4 to 6 weeks of age. 



The use of guinea pigs as food in the United States has not become 

 popular, possibly because of prejudice regarding the use of rodents 

 as food and the abundance of other food animals. 



Many institutions using guinea pigs now maintain their own colonies 

 or contract with people who raise large numbers which have been 

 developed for specific tests. Many others are supplied through 

 agencies which gather up smaller numbers of guinea pigs from 

 numerous small producers. Anyone who contemplates raising guinea 

 pigs should first arrange with a hospital, laboratory, or manufacturer 

 of biological products or drugs, or with some agency which buys guinea 

 pigs, for disposition of surplus stock. Guinea pigs are less in demand 

 for vitamin C assay than formerly since it now can be determined 

 directly by chemical analysis. The golden hamster may replace the 

 guinea pig to a limited extent in some experimentation because of its 

 greater prolificacy, shorter gestation period, and smaller size. On 

 the other hand, the characteristic reactions of the guinea pig through 

 a long period of observation make it more valuable than a compara- 

 tively new laboratory animal whose reactions have not been deter- 

 mined in many instances. 



Care and Management 



Guinea pigs do not thrive well in temperatures lower than 65° or 

 70° Fahrenheit. At temperatures lower than this they contract colds 

 and respiratory diseases and the young often are born dead or die soon 

 after birth. Drafts and too much moisture should be avoided. 



