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After dogs and cats, Guinea pigs are one of the most popular pets in the United States. On average, a female Guinea Pig (sow) goes into heat once every 14–19 days, and is receptive to males (boars) for about 6-11 hours. 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, females have a vaginal membrane that 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 if 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 show interest and try to mount her.
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 physical change in the hours just before giving birth. The pubic symphysis, the joint between the two halves of the pelvis, starts to widen to allow delivery. This happens directly in front of her external genitals. In the last hours before she delivers her pups, this separation can be as wide as 1 inch (or 2.5 centimeters).
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 very dangerous.
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 limitation, thankfully.
What To Do When You Know Your Guinea Pig Is Pregnant
Once you know your Guinea Pig sow is pregnant, you should visit your vet to 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 needs a carefully balanced diet to support the healthy development of her pups and a smooth pregnancy. Because guinea pigs can’t produce their own vitamin C, it’s essential to provide it daily — ideally through fresh vegetables like bell peppers or kale, or via a supplement if needed. Alfalfa hay, which is richer in calcium and protein than timothy hay, is also recommended during pregnancy and lactation. However, calcium levels should be monitored, as excessive intake can be harmful. Always consult a veterinarian to ensure your sow’s diet meets her nutritional needs throughout pregnancy.
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.
What Is the Average Size Litter for a Guinea Pig?
Although a Guinea Pig sow can have up 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, even though they can eat and drink like adults, guinea pig pups should be allowed to nurse for at least 2 weeks. That way, they get vitamins, minerals, other nutrients, and immunity boosters from their mother. After 2–3 weeks, they can be weaned and fed high-quality hay or grass.
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 length of the pregnancy tends to vary depending on the litter size. In other words, a guinea pig having one pup will have a longer pregnancy than one giving birth to a larger litter.
Conclusion
Guinea pigs are much different from other small mammalian pets like hamsters. They can go into heat every 14–19 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 7–8 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
