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Do Guinea Pigs Change Gender?

Changing genders is fairly uncommon in the animal kingdom. 

However, there are some fish species known for changing sexes throughout life. 

This leads many guinea pig owners to wonder if this is true and has become a popular myth in the cavy community. 

Determining the gender of guinea pigs takes a bit of experience and examination but will a guinea pig change gender?

Guinea pigs do not change gender. Sometimes it is difficult to determine the sex as males and females look very similar, and the genitalia is not particularly visible. Some males will retract their testicles into their abdomen, which may lead to confusion, but they do not change sexes.

If you are interested in breeding your guinea pigs or want to avoid mating at all costs, knowing the gender is important. 

Let’s look into guinea pig gender and whether or not they can change sexes throughout their life. 

do guinea pigs change gender

Will Guinea Pigs Change Sexes?

There is some debate about whether guinea pigs change sexes among the guinea pig. 

However, they can’t change genders. 

This means your male cavies won’t change into female guinea pigs. 

There are some bi-potential animals in the world with gonads of neither definitively male nor female sex. 

There are also asexual animals. 

Asexual animals reproduce much differently than mammals, and guinea pigs do not fall under this category. 

It is difficult to tell the gender when guinea pigs are just a few weeks of age as their genitalia is not as pronounced or easily identifiable. 

If you aren’t sure of the sex, take your guinea pig to a veterinarian to find out if they have a male or female gender identity. 

There are also some sex-typed behavior traits characteristic of each gender. 

This isn’t fool-proof, but if your guinea pig exhibits female-typical sexual behavior, it is a good start in determining gender. 

Regardless of the actual behavior of your guinea pigs or their assumed gender, they will not change sexes. 

If you discover your guinea pig as a different gender than you originally thought, they did not change sex. 

They were simply erroneously gendered, which is common when you get a very young guinea pig as it is much easier to determine the sex once the pet has grown a bit. 

How Do I Know If I Have A Male Or Female Guinea Pig?

There are a few ways to determine whether you have male or female guinea pigs. 

Some are possible to do at home, while others require the attention of a professional veterinarian. 

If you have just one guinea pig, you don’t have to worry too much about whether or not you have a male or female. 

However, if you plan on breeding or avoiding guinea pig babies, knowing the genders of your guinea pigs is very important. 

Watching behavior in guinea pigs, consulting a professional, and doing an at-home exam are ways to find the sex. 

At-Home Examination

It is possible to conduct an initial study at home with your guinea pigs to determine their sex. 

If they are very young, it helps to allow some additional time to pass so the determination is easier. 

More often than not, male guinea pigs are more often misgendered as females as their testicles have not fully developed. 

This is why many guinea pig boys at birth end up being wrongly sexed and are definitively female guinea pigs.

To conduct an at-home examination, you’ll start by looking at the shape of your guinea pig. 

Female guinea pigs will have a slightly flatter shape and a y-shaped body. 

This is hard to tell when they are very young as they are still filling into their bodies. 

Most guinea pigs reach sexual maturity between 3-6 weeks, with 4 weeks being the average. 

Around this age, you’ll be able to feel for genitalia. 

  • With females, you won’t feel anything when you feel for genitalia. 
  • With males, you’ll feel the penis. It is sometimes also visible as a straight line when you flip them over.  

Asking A Professional

Veterinarians are trained and have adequate experience in the sex identification of animals. 

If you have any doubt, bring your guinea pig to a vet to get a solid answer. 

This is especially important if you have multiple guinea pigs past 4-10 weeks old

At this age, they’ll be able to mate. 

If you don’t want to end up with a pregnant guinea pig which is a common outcome of keeping both sexes together, it’s important to know the sexes of your cavies. 

This way, it is easy to separate the males from females. 

Sex-Typed Behavior

One way to collect additional evidence for sex determination is by watching for sex-typical behavior. 

Male-typical sexual behavior involves being slightly more aggressive than that of females.

Related: Is teeth chattering a sign of aggression in guinea pigs? 

Nuzzling is another form of male-typical sexual behavior. 

Nuzzling refers to when a male will chase the female around in circles. 

As your male guinea pig matures, you will see an increased male-typical behavior, and it’s time to separate him from the ladies. 

Female-typical sexual behavior is much more laid back and subdued. 

You’ll notice this sex-typed behavior quickly as they become fertile. 

Even an infertile female will stay calm in their demeanor, but it is useful for weeding out the males. 

The female-typical sexual behavior of being laid back is a far cry from the circle’s run and energy of a male. 

The differentiation of behavior is very useful if you doubt sex. 

Chasing is an important aspect of behavior setting males apart. 

You’ll start to see this type of increased male-typical behavior at 4 weeks when your guinea pig reaches sexual maturity. 

Sex-typical behavior is useful in determining not only gender but also sexual maturity. 

Can I Neuter My Male Guinea Pig?

For many animals, genital surgery is done to prevent mating and pregnancy. 

If you start noticing breeding behavior in guinea pigs, neutering the males to prevent mating is possible. 

Female animals are less likely to be altered as the neutering process is much simpler and less invasive. 

Healthy individuals will recover quickly without too much time. 

Further Reading: Can you neuter a guinea pig?

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