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Home > Guinea Pigs > How Often Do Guinea Pigs Go Into Heat? Sexual Maturity, Reproduction & Gestion Periods

How Often Do Guinea Pigs Go Into Heat? Sexual Maturity, Reproduction & Gestion Periods

Two guinea pigs on the grass

After dogs and cats, Guinea pigs are one of the most popular pets in the United States. On average, a female Guinea Pig goes into heat once every 15 days. Of course, that only starts once a Guinea Pig hits her sexual maturity.

Knowing how often Guinea Pigs go into heat, you might have several other questions about this cute animal’s reproductive tendencies. How can you tell when a Guinea Pig is in heat is a good one, as well as how long they stay in heat and at which age they start? Read on for the answer to these questions, plus tips and advice about these popular pets!


How Can You Tell When a Guinea Pig Is in Heat?

Surprisingly, when a female Guinea Pig is in heat, the male will make a vocal sound called rumbling. Rumbling sounds like purring but is lower pitched. Occasionally the female will rumble also, but most of the time, she will be restless and moving around her pen more than usual. Also, a membrane covering the female Guinea Pig’s vagina opens when she’s in heat. After mating, this membrane closes until she’s ready to mate again, usually after her babies are born.

Male Guinea Pigs will also constantly mount females when they are in heat, something you will no doubt notice if you have a male and female. If you’re unsure a female Guinea Pig is in heat, one of the easiest and fastest ways to tell is to put a male in her cage. If she’s in heat, the male will immediately try to mount and mate with her.

close up of a brown and white guinea pig
Image By: rubyclement, Pixabay

How Long Does a Guinea Pig Stay in Heat?

Once a female Guinea Pig enters heat, she stays in heat for 16 days. Interestingly, however, she will only be receptive and allow a male to mount her for about 8 hours during those 16 days. Also, within 15 hours of giving birth to her litter, a Guinea Pig can return to heat and become pregnant again. In other words, she can wean her pups and be pregnant at the same time.


How Can You Tell if Your Guinea Pig Is Pregnant?

Although difficult to notice in the first few days and weeks, a Guinea Pig can double in size towards the end of her pregnancy. This is one of the few signs you’ll notice because Guinea Pig females (aka sows) don’t build a nest for their pups like many smaller mammals.

You might notice another change in the hours just before giving birth. That’s when the sow’s pelvis will begin to separate and widen, which happens directly in front of her external sex organs. In the last hours before she delivers her pups, this separation can be as wide as 1 inch.

Sleepy guinea pig
Image By: Shchus, Shutterstock

When Is the Best Time to Breed a Guinea Pig Sow?

Guinea Pig sows must be bred before they reach 7 months of age. The pelvic separation mentioned above must occur before a Guinea Pig sow reaches 7 months. If she’s not bred before this time, her pelvis won’t widen, making delivery of her pups impossible.

Guinea pig sows bred for the first time after 7 months will need a Caesarean section, which is extremely difficult to perform. Most won’t survive the procedure, and their pups won’t either. So, breeding a Guinea Pig sow before she reaches 7 months is critical. Male Guinea Pigs don’t share this health issue, thankfully.


What To Do When You Know Your Guinea Pig Is Pregnant

Once you know your Guinea Pig sow is pregnant, you must ensure she stays safe and has a successful pregnancy.

1. Remove the Male From The Sow’S Pen

Removing any males from the pregnant sow’s pen is essential so that they don’t become pregnant again right away after giving birth. Remember, a sow can become pregnant within 15 hours of giving birth!

2. Supplement Your Sow’S Diet

While pregnant, your Guinea Pig should get certain vitamins and minerals to help her babies grow and ensure her pregnancy is successful. They include Vitamin C, calcium, and alfalfa hay. Vitamin C is essential as Guinea Pigs can’t synthesize this vital vitamin on their own. Giving your pregnant sow a small piece of fruit daily is an excellent idea.

guinea pig raspberry
Image By: Eva Zuy, Shutterstock

3. Ensure Your Sow Has Plenty of Regular Hay

She will need this to gain weight while pregnant and help feed her pups.

4. Bring Your Sow Indoors for More Warmth & Comfort.

This is especially true in winter. However, a pregnant Guinea Pig should be kept inside any time of year for safety. At the very least, moving their pen into a well-insulated shed, garage, or other outdoor shelter is a good idea.

5. Don’t Overfeed Your Guinea Pig Sow With Pellets

Many owners make the mistake of overfeeding their sows with pellets or muesli. The problem is that the sow’s babies might become so large due to overfeeding that passing them through her birth canal is extremely difficult.

guinea pig eating pellets
Image By: PxHere

What Is the Average Size Litter for a Guinea Pig?

Although a Guinea Pig sow can have one to six pups, the average litter size is three. For the average sow, the occasional stillbirth or spontaneous abortion is normal. It’s also worth noting that the first litter or two most Guinea Pig sows have are small. As they have more pregnancies, their litter size increases.


What Do Guinea Pig Pups Look Like?

If you’ve ever seen hamster, mouse, or gerbil babies, you know they’re tiny, pink, and furless. The difference between these animals and Guinea Pigs is that Guinea Pig pups are born almost fully mature! They have all their fur, their eyes are open, and they also have teeth. In fact, a newborn Guinea Pig can drink from a water container and eat solid food!

However, just because they can eat and drink like adults, Guinea Pig pups should be allowed to nurse for at least 2 to 3 weeks. That way, they get vitamins, minerals, other nutrients, and immunity boosters from their momma. After 3 weeks, they can be weaned, but occasionally, pups can still be allowed to breastfeed if possible.

Image By: Pxfuel

How Long Are Guinea Pigs Pregnant?

One reason that Guinea Pig pups are almost fully developed when they’re born is that Guinea Pig sows have a very long gestation period. The average is 65 days, but some can last upwards of 72 days. What’s fascinating is that the size of the litter is directly in contrast to the length of the pregnancy. In other words, a Guinea Pig having one pup will have a longer pregnancy than one giving birth to five or six pups.



Guinea pigs are much different from other small mammalian pets like hamsters. They can go into heat every 15 days, get pregnant within 15 hours of giving birth, and their pups are born ready to face the world on their own (almost).

One of the most important things to remember if you plan to breed your Guinea Pig sow is that it must be done before she reaches 7 months of age, lest she has severe problems giving birth. If that’s your plan, we hope the information provided today helps your Guinea Pig have a successful pregnancy!

Featured Image Credit: Charleen Magne, Shutterstock

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