Literally 'Dutch pig' — exactly as misleading as the English 'guinea pig' (the animal is from the Andes, neither Dutch nor a pig). It probably entered Chinese via Dutch traders shipping the pets through Asia in the 17th century.
usage
The biological/formal name is 豚鼠 (túnshǔ, 'pig-rat'). 荷兰猪 is the common name used by pet shops and owners.
