Any breeding undertaking should be taken seriously and left to only experienced cavy breeders. Breeding should not be performed as a school or scientific project or to allow children to witness the miracle of birth. Too many guinea pigs are left homeless and in humane societies.

The most important aspect of guinea pig breeding is that the females (sows) MUST be bred between 4 and 7 months of age. If breeding occurs after this time, serious and often fatal (to both female and young) problems associated with delivery occur. The pelvis of the sow fuses at an early age, which decreases the size of the birth canal. The young are born very large and will not be able to pass through the canal of an older guinea pig and delivery of the young will be impossible without a caesarean section. If they are bred early, the sow's pelvis is able to expand under the influence of certain hormones and she will rarely have complications with delivery.

Male guinea pigs (boars) will show sexual behavior as early as 3 to 4 weeks, but are unable to produce viable sperm until 11 to 17 weeks of age. The boars should be at least 4 months old before breeding.

The young are called pups (not piglets) and are well developed at birth. They are born with their eyes open, fully furred and standing within an hour of delivery. The pups are also able to eat solid food and drink from a bowl within hours to just three days after birth, but it is recommended to allow them to nurse for three weeks.

Common Diseases and Disorders

External parasites: lice, mites

Pneumonia

Heat stress

Vitamin C deficiency

Antibiotic associated enterotoxemia

Bacterial enteritis

Malocclusion

Pododermatitis

Ovarian cysts

Urinary calculi

Dystocia