Breeding Guinea Pigs Responsibly

Before deciding to breed from your guinea pig it is very important to consider where the youngsters will go. Will you keep all of them or do you need to arrange homes?

Guinea pigs can have litters of up to around 8 babies. Rescue shelters often have guinea pigs that are ‘homeless’. It is also important to consider the background of the guinea pigs that you plan to breed. Guinea pigs can carry inherited disease (particularly, but not limited to, the Dalmatian and Satin breeds) some of which can be very serious.

Baby Guinea Pigs

Guinea pigs are one of a group of rodents called the hystricomorphs with an unusual reproductive physiology and breeding strategy, as unlike many other rodents baby guinea pigs are fully furred with open eyes and able to run and feed within a short time of birth.

Breeding Age

Guinea pigs mature at around 3 months but should not be used for breeding for another three months. After about twelve months of age the female guinea pig’s pelvic bones become more tightly fused and if she has not had a litter by that time, producing young can be more of a problem. The average gestation period is up to 72 days; this must be remembered when establishing whether a female is too old to breed.

the female guinea pig will be able to mate again within a few hours of giving birth

Pregnancy Toxaemia

The large size of the babies is part of the reason that guinea pigs are predisposed to pregnancy toxaemia. This is a metabolic disorder resulting in low blood calcium and high blood pressure.

It manifests as loss of appetite in the early stages, deteriorating to muscle twitching and coma.

Prompt veterinary attention can save animals but the problem can be reduced to a minimum by providing plenty of water and green foods during pregnancy, as throughout life.

Foetal Death

There is a relatively high incidence of dead babies in guinea pig litters. Interestingly the guinea pig, along with other hystricomorph rodents, starts off with a much larger set of foetuses in her uterus but many of them die before birth, many very early on but some late in gestation or even at birth.

The reason is unclear but it may be a mechanism of producing the maximum number of babies for a limited and varying food supply. The large size of a guinea pig’s babies also mean that she is more likely to have problems with giving birth than other rodents so frequent checks throughout the day and night should be carried out from a few days before her due date, in case she is having any difficulties.

As with many rodents the female guinea pig will be able to mate again within a few hours of giving birth. She should not be allowed to, however, since it is much better that she has time to replenish her metabolic reserves before becoming pregnant again.


It is not uncommon for guinea pigs to be incorrectly sexed when babies, particularly if being supplied via a pet shop, however it is relatively easy to tell the two genders apart. The difference becomes more apparent with age but gender can be determined from birth.

  • In the female, there is a “Y” shape formed in the middle of the round hairless genital area.
  • In the male this is an “i” shape. Once a few weeks old the penis of the male can be protruded by pressing gently above the genital area.
Breeding Guinea Pigs
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