Guinea Pig

Guinea Pigs are mentioned only once and not seen in the game School of Dragons.

Description
Guinea pigs are a species of rodent belonging to the family Caviidae. They originated in the Andes of South America and were originally domesticated as a source of food, though they are now commonly kept as pets around the world. It is unclear where their name comes from, as they are neither from Guinea nor related to pigs.

Function
Guinea pigs have no use in the DreamWorks Dragons Franchise, other than as a phrase to refer to someone being used for a potentially dangerous test.

In reality, guinea pigs are a common pet in much of the world, although some cultures do use them as a food source.

School of Dragons
"Wonderful, wonderful. A new guinea pig - I mean, a new helper!"

- Ruffnut Thorston in School of Dragons

Guinea pigs are mentioned by Ruffnut Thorston after the player accepts her invitation to take part in her recently created Death Race on Dragon's Edge.