Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
guinea pig [ˈgɪnɪ-] n (animal) морска́я сви́нка#; (fig) "подо́пытный кро́лик"
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.
Русский: