How Do Guinea Pigs Mate? | All You Need to Know!

Guinea pig breeding is dangerous. This means that it should only happen for a good reason and never for fun. There are high mortality rates associated with pregnancy and birth.

How do guinea pigs mate? Sows (female guinea pig) have several periods per year when they’re sexually receptive. These periods are called heat or estrous cycles, and they’re 14-19 days long. They only get pregnant in a small 12-48 hour window while she’s in her cycle. Therefore, a breeding pair should always be together during the heat.

In this article, you can identify how guinea pigs mate and their pregnancy.

How Do Guinea Pigs Mate?

How Do Guinea Pigs Mate

Sows are polyestrous. It means that they have several periods per year when they’re receptive to sexual relations. These are called estrous cycles, also known as heat cycles, and they last 14-19 days.

A breeding pair should always be together during the heat since there’s only one small window (12-48 hours) in which the sow can get pregnant.

Within the hours following successful breeding, a copulatory (vaginal) plug can be found in the sow. This plug is a solid mass that theoretically prevents another male from mating with the female right after she’s been impregnated.

What to Do Before Mating Them?

What to Do Before Mating Them

There are several steps to take before mating guinea pigs:

Step 1: Take each guinea pig to a veterinarian. If they’re introduced while sick, they’ll infect each other. There should be at least two weeks between a mite treatment and a first meeting.

Step 2: Quarantine a new piggy for two weeks. This is another measure to ensure that neither one has mites, parasites, or illness. During this time, it’s essential that both be happy and calm in their environment.

It’s vital that the new one has some time to get accustomed to its surroundings, and that each piggy has enough cage space (120cm x 50cm x 50cm) and bedding.

Start swapping items, such as bedding and toys, between cages. This is called scent swapping, and it helps the guinea pigs slowly get used to each other’s scents. Therefore, they will not feel stressed or threatened once they meet.

Step 3: Introduce the boar and the sow. Make sure that there’s only one boar with a breeding soar. Otherwise, the males will fight fiercely for the female. Reduce stress as much as possible for her by keeping her in her regular cage without the pressure of living with her female companions.

Although she should continue to get some social time with them, she should live with her mating partner unless she’s not ready to breed. A sow will show her teeth and spray a male when she doesn’t want to mate.

Pregnancy of Guinea Pigs

Pregnancy of Guinea Pigs

Gestation is relatively long for rodents, 60-72 days (68 on average) with 1-6 litters per birth. Because of the extra time, babies are born furry, toothed, standing, with open eyes, and able to eat some solid foods.

Some signs of pregnancy are a distended abdomen and a doubling or tripling in food and water consumption. Keep in mind that animals may eat more because of cold weather, a growth spurt, or an underlying illness.

Also, a pregnant sow will double in weight. So, a gradual increase from the average 700 – 900 grams (1.5 – 2 lbs) is a good sign unless the piggy is still very young and growing (under 6-8 months).

Two weeks after mating, fetuses can be felt gently from outside. The sow must be handled very carefully because the slightest pressure applied to the abdomen can harm the fetuses and the sow. She must be placed on a towel on a hard surface that’s close to the ground. Gently use your thumb and forefinger to feel for a single or several similar-sized lumps.

The kidney or bladder could also feel like bumps, and even poop pellets could be confused with fetuses. Even if you know to differentiate, there’s still no guarantee that those bumps are fetuses because they could be ovarian cysts or tumors. It’s crucial to visit a veterinarian if you feel something unusual or if you’re trying to determine whether a piggy is pregnant.

Lure the sow with fruits, vegetables, or treats into a transport cage and go to the vet. Don’t pick her up by the stomach or you could harm the fetuses. The vet will do a physical examination to determine whether the sow is pregnant. It’s important to ask for an ultrasound, as there’s no guinea pig pregnancy test.

Complications Occur in Pregnancy of Guinea Pigs

Complications occur in pregnancy of Guinea Pigs

What Is Dystocia?

If a sow doesn’t give birth before she’s seven or eight months old, the fibrous cartilage of her pubic bones fuses, causing a condition called dystocia. In dystocia, the pelvis is too tightened for babies to pass.

Its symptoms include pain, discomfort, vaginal or uterus bleeding, and prolonged pregnancy. A fetus can get stuck in the birth canal and stay there no matter how much the sow is straining herself, usually resulting in both of their deaths.

There are several ways to avoid death with dystocia:

  • Breeding females in their prime (4-6 months of age)
  • Housing boars and sows separately to avoid breeding altogether
  • Neutering boars and possibly spaying sows
  • Cesarean sections are an option, but not recommended as they’re very dangerous and have high mortality rates.

What Is Toxemia?

Toxemia usually occurs anywhere between the last two or three weeks of pregnancy to the first week after it. Also known as ketosis, it’s an excess of ketones in the blood, resulting in an inability to excrete them from the body properly.

Ketones are a product of fatty acid breakdown that becomes an energy source in cases of low blood sugar. Male and female piggies, especially those in their first or second pregnancy, should have a diet with enough carbs to avoid the condition.

A pregnant piggy or her fetuses can die from ketosis with no symptoms. Still, signs to look out for are a loss of energy, appetite, thirst, getting muscle spasms, lousy coordination, clumsiness, large litters, and obesity.

Its important to know how to avoid ketosis. The following are some of its ways:

  • Pay attention to a loss of appetite at the end of a pregnancy and make sure that the sow is eating enough sugar
  • Make sure that the sow is using all of her energy sources by exercising before her due date
  • Keep her surroundings stress-free
  • She could have a genetic condition of undeveloped blood vessels in the uterus.

Neutering to Avoid Breeding

Neutering should happen when a piggy is 4-12 months old (up to 2.5 years), and only for medical or reproductive reasons.

If a male is to be put with females, it’s best to castrate it. When living with sows, the two will definitely mate and produce a considerable amount of offspring. It’s crucial to fix the male if you want to avoid having enormous amounts of guinea pig babies that no one can take care of.

Neutering (castrating and spaying) has medical advantages:

  • Eliminates the risk of uterine and testicular cancer. Up to 60% of guinea pigs develop cancer.
  • Removes the risk of other uterine diseases. Many uterine disorders can be life-threatening.
  • Prevents glandular problems in older boars. Boars are susceptible to issues with the skin and rectal glands.
  • Helps the overpopulation issue of guinea pigs.

What Is the Best Way to Breed Guinea Pigs?

What is the best way to breed guinea pigs

If breeding two guinea pigs still seem like a viable option, there are several requirements to stick to:

  • Double check their genders by looking above the anus. Males have an O shaped area with a slit or visible testicles. Females have a soft, Y shaped area.
  • Only mate animals during the appropriate age, otherwise, the sow will probably die. Sows should have time to rest between pregnancies to ensure healthier litters.
  • It’s professional to breed the most outstanding sows and boars in each group. Strong boars have a broad head and bold eyes. Good sows should have a nice muzzle and a good head shape with healthy eyes.
  • It’s best to verify the parentage of each to avoid having babies with deformities or mutations.
  • Have separate pens for boar and sow babies, and ensure that they have enough space. Add toys and hiding holes in the cages.
  • Buy a supply of extra hay, bedding, food, and water bottles.
  • Ensure that there’s enough time in the day, week, and month to clean the cages and appropriately care for every single guinea pig.


Guinea pig breeding should be done by professionals and only for reproductive reasons. Pregnancy and birth have high mortality rates because of conditions like dystocia and toxemia or because of inappropriate care or handling of the pregnant sow. It’s dangerous, and it’s not recommended to do it at home for fun.

List of Sources

Observations on the Sexual Cycle of The Guinea Pig

Care of Guinea Pigs

True Pregnancy Toxemia (Preeclampsia) In the Guinea Pig (Cavia Porcellus)