Do Female Guinea Pigs Have Periods?

Guinea pigs (Cavia porcellus) are popular pets. These small, tailless rodents are indigenous to South America, but they are no longer found in the wild. Like other mammals, the females give birth to live young and feed them with milk from mammary glands. They also have estrus cycles, which are different from periods. Read on to learn more about guinea pig reproduction.

An Overview of Guinea Pig Reproduction

Female guinea pigs, or sows, generally reach sexual maturity between 55-70 days, with an average of around 67 days. The males, called boars, reach maturity between 60-90 days, although both males and females may mature sooner. Guinea pig reproduction is influenced by how their human owners house them. Depending on their living arrangements, guinea pigs may be kept in monogamous pairs or in groups, which can lead to polygamous breeding.

Sows can breed at any time throughout the year, but spring is the most common. Gestation lasts anywhere from 59-72 days, with 63–68 days on average. They can give birth to up to five litters a year. Litter size is 1-8 pups, but 2-4 pups is more typical.

The Female Guinea Pig Mating Cycle

Estrus occurs throughout the year, with each cycle lasting about 16 days. This is commonly referred to as “going into heat.” However, unlike animals with menstrual cycles, female guinea pigs do not experience periods or bleeding. Signs that a female is in heat may include swollen genitals, running around the enclosure, low-pitched vocalizing, and arching her back with her rump in the air.

Female guinea pigs are fertile for around 6-11 hours. Mating usually takes place within 20 hours of ovulation, typically at night. Sows can become fertile again shortly after giving birth. Some sources note that the female may be able to conceive as early as 2-15 hours after producing a litter. Experts also estimate that between 60%-80% of sows will become pregnant again if they are mated.

If a guinea pig is to be bred, it is crucial that this occurs before the sow reaches eight months of age. During the birthing process, the pubic bones must be able to separate where the sides of the pelvis meet. However, there is a joint of fibrous cartilage between the pubic bones called the pubic symphysis that hardens as the guinea pig ages. If the sow has not had a pregnancy before adulthood, she may not be able to deliver the pups normally. It should also be noted that reproduction can reduce a guinea pig’s lifespan.

Guinea Pig Parenting

Parental care of the pups is limited because newborn guinea pigs are precocial. This means they are born well-developed, mobile, and able to eat solid food while they are suckling. Newborn pups weigh between 3-4 ounces. They are born with hair, and they can see and run shortly after birth.

Guinea pig mothers have a single pair of mammary glands to nurse their young, but the pups can eat soft food within the first two days. Guinea pig pups nurse until they are about three weeks old, at which time they can eat the same foods as adult guinea pigs. Veterinarians advise that young guinea pigs should be carefully handled as early as 2-3 weeks old. This is the period when pups best form bonds with humans and come to accept being held.