Sexing Guinea Pigs: How to Determine Gender?

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When you choose to keep more than one Guinea pig, knowing their gender is one of the first things you should know. 

Since Guinea pigs are capable of breeding at an early age of 3 – 4 weeks, it is vital that you are aware that you’re getting the same sex to avoid unplanned breeding.

Furthermore, the gender plays a big role when it comes to their behavior. To be sure of the cavy’s gender when adopting or buying, knowing how to sex a Guinea pig can be very handy so you know you’re getting your preferred gender.

gender genes

Determining the Guinea Pig’s Gender – What to Do and What to look for?

1. Size difference

Male Guinea pigs or boars are generally slightly larger and have bodies that are longer compared to females. When they reach sexual maturity, male cavies can weigh up to around 700 grams, while adult female cavies can grow up to 450 grams. You will notice that the male’s scrotum pouches are visible just by looking at the bottom.


2. Nipples

Do male guinea pigs have nipples? Both genders have nipples but females or sows have nipples that are more noticeable. Those of the female cavies are much more pronounced and the hairs surrounding them are much further away, forming like a circle especially when they just gave birth and are nursing their baby cavies.

However, don’t rely solely on checking the nipples of cavies since most of the time, both males and females can show similar appearance, especially with pups and when they’re in the early stages of their lives.

two cute guinea pigs

3. Genitals

The distance between the genitals and the anus of cavies is the first thing you need to observe in checking their gender. Their anus will look like a vertical slit that is usually brown or grey in color and is located just below the genitals.

The female’s vulva has a very short distance from the anus, while male’s penis usually has 2 – 3 inches distance.

Boars. Their penises will bulge on top of the slit of the anus forming an “i” shape on the bottom of their bodies. When they reach sexual maturity, the penis will be more pronounced and the bulge will become more distinct due to the presence of the foreskin and the testicles.

However, there are times that it can be difficult to see the penis. To make it come out, you can gently apply pressure on the spot where the genitals should be. You can also gently rub your fingers on the same spot and feel the ridge to confirm the penis’ presence.

Sows. At first glance, you’ll see that the female’s bottom will look like the letter Y. Compared to boars, the female’s genitals bulge from the skin, although it will usually be smoother and appear to be flatter.

You can also make sure that you have a female piggy when you follow the procedure done with boars. When you apply pressure and nothing comes out or when you rub your fingers on the spot where the genitals should be and don’t feel any ridges, then you are holding a female cavy.

When you do the sexing for the first time, you can get confused due to the resemblance especially that both genders can show the “Y” shape on their bottoms. That said, always follow the necessary steps as stated above.

If, however, you’re still unsure if you’ve successfully determined the sex of your cavies, going to your nearest vet that specializes in small pet animals is always a great option. Also, you can go online for images, to guide you of the signs you need to know.

Why is it Important to Determine the Sex of Your Guinea Pigs

The procedure performed to determine the sex of cavies can also be a way to determine if they’re healthy and well. Like other small pet animals, Guinea pigs are susceptible to developing certain diseases like Wet Tail, diarrhea, and bumblefoot or pododermatitis.

Sexing is also the first step when you introduce two or more Guinea pigs in a cage. Most of the time, two cavies of the same gender tend to live harmoniously together, while cavies of the opposite sex are a different story. Unless they’re housed and raised together when they were babies, females can exhibit aggressive behavior towards their male counterparts.

Carlye Yancey
Carlye Yancey

Between internships, volunteering, and paid jobs over the last 4 years, I have pretty much-gained experience with domesticated animals. Currently being in school for my veterinary technology degree, I spend my leisure time with 3 critters that I own.

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