The guinea pig, Cavia porcellus , is a mammal of the order Rodentia, sub-order Hystricomorpha ("porcupine-like") and family Caviidae.
Three basic breeds of guinea pigs exist. The English (short-haired), Peruvian (long-haired) and Abyssinian which has a rosette hair pattern.
Guinea pigs have several unique biological characteristics. Guinea pigs are herbivores and unlike most laboratory animals, except non human primates, guinea pig require a nutritional source of Vitamin C.
Guinea pig can be grouped by their microbial colonization: Specific Pathogen Free (SPF) guinea pigs are free from know bacterial, viral, and parasitic pathogens. as opposed to "conventional" guinea pigs, which are not known to be free of pathogens. Both type of guinea pig are available for purchase.To maintain the SPF microbial status of guinea pig may require that animals be housed in more stringent conditions that prevent the introduction of other pathogens such as isolation separate rooms or barrier housing. This type of housing is available at the University of lowa, though it is typically not required or utilized by investigators.