For both guinea pig and rat, the initial expense can be high for cage and accessories. They are both interesting to watch and both are gnawers. Both need exercise and handlling out of the cage. They should be supervised in play outside of the cage so they don't get into any tight spots or start chewing on things they shouldn't. Guinea pigs can live solo while rats are social animals and should be kept in pairs. Some guinea pigs are noisy. Guinea pigs live about 4-8 years while rats live only 2-3 years. Rats are mainly nocturnal animals and need daily handling and attention. They are intelligent and easily trained. Both can be skittish if not handled at an early age. Guinea pigs are larger and eat more. They both make good pets - the choice has to be yours.
