ABSTRACT
The guinea pig (Cavia porcellus) has historically been considered a hystricomorph mammal belonging to a family of burrowing rodents (Caviidae) native to the Western Hemisphere. More recently, sequencing of the mitochondrial genome and molecular analysis has indicated the guinea pig should be considered in a separate taxonomic group currently of intermediate rank. Guinea pigs are monogastric and have a completely glandular stomach in contrast to other rodents such as mice and rats which have glandular and nonglandular gastric components. Guinea pigs serve as a model of the circulatory form of pregnancy toxemia, where the aorta caudal to the renal vessels undergoes fetal compression due to the relatively large size of the conceptus as guinea pigs are precocious at birth compared to other rodents. The guinea pig does not require growth hormone for growth, as is the case for other mammals. Insulin-like growth factor I and II are responsible for growth in guinea pigs.
