Can Guinea Pigs Change Genders?

As much as absurd it sounds, many Guinea pig owners talk about Guinea pigs changing their genders. So, can guinea pigs change genders? In reality, Guinea pigs can’t change genders and are born either male or female. However, during their younger days, Guinea pigs are sometimes hard to distinguish as their genitalia aren’t developed to a certain degree. That’s why it’s important not to breed your pig until it gets to a certain age.

That being said, we’ll talk about Guinea pig genders as well as how to distinguish male from female one, so you don’t make a mistake next time you want to breed your Guinea pigs.

How Can Guinea Pigs Change Sex?

They simply don’t change sex! However, it is possible for male Guinea pigs to retract their testicles, making them look like the female Guinea pigs. This is especially strange and requires constant attention, to avoid making a mistake. But, it’s not only common for Guinea pigs, but also for other animals to retract their testicles inside the abdomen.

Since young Guinea pigs have fairly small testicles, it’s even harder to safely tell if that Guinea pig is male or a female. Nevertheless, you’ll be able to determine the gender only if you pay special attention to Guinea pig’s behaviour to either male or female pigs.

How to Determine Guinea Pig’s Gender?

If Guinea pigs can’t change their genders, how do you assume it? First, you’ll need to use your hands as it can’t be determined only by the looks. When it comes to female Guinea pigs, they have a bit flatter look with a well-developed ‘Y’ shape. And if you touch the genitalia area with your hand, you won’t be able to feel any kind of protruding. On the other hand, male Guinea pigs are a bit easier to distinguish. They have a line with a penis that can be seen and it’s in the shape of a line.

When touching the genitalia area, you’ll be able to feel the protruding. And if your Guinea pig is a bit older, this touch will also greatly protrude the penis, which is proof that you have a male Guinea pig. Still, if you aren’t 100% sure, it’s best to take your Guinea pig to a veterinarian and let him determine the gender.

When Do Guinea Pigs Become Fertile?

Before we delve deeper into this subject, it’s important to mention one thing. By breeding a Guinea pig, its lifespan is being reduced, and this only applies to female Guinea pigs. When it comes to breeding them, unfortunately, you have very little time to do that.

Although female Guinea pigs become fertile after 4-10 weeks of age, it’s not recommended to breed them immediately after that period. The recommended time to start is about four months of age. During this time, a female Guinea pig isn’t yet at its adulthood, meaning that it’s the perfect time to start breeding. But, an important thing to remember is that you do your breeding before eight months of age.

Breeding a female Guinea pig at eight months of age or more is sometimes going to decrease its lifespan drastically. And after eight months, a female Guinea pig is slowly reaching its adulthood, meaning that it sometimes can’t deliver offsprings successfully. In this case, a veterinarian with a fair amount of experience should help your guinea pig bring the babies.

As for the male Guinea pigs, breeding can be done a month earlier – at three months of age. While the male Guinea pig can mate at any time of the year, female Guinea pigs often have an estrous cycle in the spring. The length of this cycle is usually about 16 days, and the new estrous cycle begins right after giving birth.

Neutering a Guinea Pig

If you don’t want your Guinea pig to give birth, neutering can be done. But, neutering a small animal is a complex process, especially when we talk about the surgery. It DOES carry some risks with it, and it’s much harder to spay a female than a male Guinea pig.

On top of that, Guinea pigs are small animals, and small animals usually don’t react well to anesthesia or surgery in general. The safest way to keep your Guinea pigs from mating is, of course, keeping your male and your female Guinea pigs in a different cage.

On the other side, if you strongly decide to neuter your Guinea pig, make sure to choose a veterinarian with lots of experience in this subject. After the surgery has been done, it’s important to let your Guinea pig recover in a quiet place, separated from the other pigs. Of course, during the recovery time, you should give it plenty of quality food and Vitamin C.

Can Guinea Pigs Be Hermaphrodites?

Not exactly. Although Guinea pigs can retract their testicles, this doesn’t make them hermaphrodites or female Guinea pigs. Unlike some animals which can be hermaphrodites, Guinea pigs are either male or female. A classic example of an animal being hermaphrodite is a snail.

Most snails are hermaphrodites which can easily be proved by putting one snail in an empty tank. Even if there aren’t other snails, you’ll see an increased number of them each day.

But, not every type of snail is hermaphrodite. Some snails do require a combination of male and female to produce offspring, but a vast majority of them are true hermaphrodites. And when it comes to changing genders, there isn’t a mammal on this planet that can do that.

Some say that fish and crustacean species have these abilities, but even then, changing gender is very rare. With Guinea pigs, not only that this doesn’t happen, but it’s completely impossible. So, if you worry about your male Guinea pig turning into a female, that just isn’t going to happen.

Male of Female Guinea Pigs?

Should you buy a male or a female Guinea pig?

Well, that’s a good question! When it comes to behaviour, neither of these will show any significant difference. Of course, a female will produce offspring, while the male one will not.

The real question is do you want the offspring?

Do you want to breed Guinea pigs?

If your answer is positive, you should get either female or simply both. And if you want to have only one Guinea pig, you can go with either choice, but neutering is sometimes obligatory.

As we mentioned before, neutering a male Guinea pig is much easier than neutering a female one. So, if you plan to do this, you should opt for a male Guinea pig. It’s also important if you already have a Guinea pig or a couple of them. If you have a few males, it’s better to buy a male and not a female.

The reason for this is that all of these male Guinea pigs will want to mate, and a single female won’t be able to always keep them off her. And if you plan on buying a male Guinea pig, introducing it to your older males is crucial, as fights can occur.


If you came all the way here, you already know the answer to the question. But, if you’re in a bit of hurry, we have a shorter version for you.

No, Guinea pigs can’t change their gender!

Since male Guinea pigs can retract their testicles, it’s often mistaken that they can magically change gender, although it’s opposite. A male Guinea pig will be born as a male and die as a male, regardless of this strange ability. As for the female Guinea pigs, they also can’t change their gender and breeding is best in the period of 4 to 8 months.

Before you get a Guinea pig, you should always carefully choose between male and the female. If you want only one Guinea pig, it’s best to buy a male one. However, it’s quite hard to have only one, as they are so adorable!