Brazilian guinea pigs are medium-sized animals. They have an almost non-existent tail, which length is only 2.4 mm. Their dorsal fur is dark olive-brown mixed with brown and black. The underparts are a pale grey or yellowish-grey. These pigs have four toes on their forefeet and three toes on their hind feet. Males in this species are larger than females.
Brazilian Guinea pigs are found in South America. Thier range extends from Colombia, Ecuador and Venezuela to northern Argentina. They inhabit open grasslands and savannahs and also may be found in the highlands of the Andes mountains.
Brazilian guinea pigs are mainly diurnal creatures. They live in small family groups that consist of one male, one or two females, and their young. These guinea pigs come out to forage in small groups mainly early in the morning and in the evening. After that they seek cover in dense shrubs. They do not dig burrows but make an intricate maze of surface tunnels that are 8 to 12 cm (3 to 5 in) wide. Brazilian guinea pigs communicate through auditory signals and scent marks. Males are known to mark their mates and defend them from rival males.
Brazilian guinea pigs are polygynous. A single male mates with multiple females. Breeding takes place at any time of year but mostly in the austral summer. The gestation period is about 62 days and females can have five litters in a year. The average number of young is two but may range from one to five. Soon after birth pups can move on their own. They start eating solid food when they are 3 days old and are weaned by 25 days old. Young Brazilian guinea pigs are ready to breed at around 30 days of age.
There are no major threats to Brazilian guinea pigs. They are sometimes hunted for food.
According to IUCN, Brazilian guinea pigs are locally common and widespread throughout their range but no overall population estimate is available. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are stable.