Cavia is a genus in the subfamily Caviinae that contains the rodents commonly known as the true guinea pigs or cavies.

[1] The best-known species in this genus is the domestic guinea pig, Cavia porcellus, a meat animal in South America and a common household pet outside that continent.

The species are very similar in habit and appearance, the long and relatively rough fur is usually grayish or brown to reddish-brown in color.

They have only a slight interorbital constriction of the skull, pan elongated paroccipital process of the occipital bone, a relatively short hard palate and enlarged tympanic cavity.

[5] The skulls of the mountain cavies correspond to those of the true guinea pigs, but are significantly more compact and rounded.

However, this uncertainty is largely of historical interest, as abundant molecular genetic evidence now conclusively supports classification of Cavia as rodents.