They carry a lethal gene which may be fully expressed when they are bred together. Be careful when feeding clover and cabbage, while both these foods are healthy for your guinea pig, they can cause gas. For this reason many will recommend against breeding two Dalmations to each other. If the offspring of such a mating survive they are usually born without eyes. Guinea pigs will generally be ready for breeding by 12 weeks of age, though they reach sexual maturity before then.
Males tend to mature later, being sexually mature by eight to ten weeks.
Mature females will go into estrus approximately every two weeks. The average female guinea pig will undergo a gestation period of 63 days. The litter consists of two to four babies. Babies are weaned sometime between 21 and 28 days after birth. It is generally not recommended to continue breeding guinea pigs after they reach two years of age.