How to Tell the Difference Between a Male and Female Guinea Pig?

By Eva López. July 25, 2022
How to Tell the Difference Between a Male and Female Guinea Pig?

As with most mammals, there are natural differences between female and male guinea pigs. Both can be wonderful companions when properly cared for, but the gender differences can still affect their character, health, and life expectancy. It is important to understand the differences between male and female guinea pigs, especially if you want to avoid unwanted pregnancies that could potentially endanger female guinea pigs. In spite of the fact that many veterinarians offer guinea pig sexing services, it is also possible to determine your pet's sex without the assistance of a veterinarian.

The following AnimalWised article explains how to tell the difference between a male and female guinea pig.

When can you tell a guinea pig is male or female?

Due to the small size of guinea pigs, it is difficult to distinguish males and females immediately after birth. Therefore, you must wait some time before examining the genitalia. Normally, after two weeks of life, when weaning also takes place, you can already see differences between the sexes with the naked eye. However, since the animals are still very small, and you are not an expert, you might draw the wrong conclusions. Even people who are experienced in caring for and raising guinea pigs can make mistakes in determining the sex if the animals are still too young. So if you have just adopted a baby guinea pig, and you are not sure of its sex, you should consult a veterinarian.

When do guinea pigs reach sexual maturity?

Females usually reach sexual maturity between three and five weeks of life, while it can take two to four weeks longer for males, with the usual average being four to six weeks after birth. If young males and females are housed together, they should be separated at this age, or they will likely breed.

If you want to learn more about the reproductive process of guinea pigs, we recommend you read this other article about heat in guinea pigs.

How to examine a guinea pig

Male and female guinea pigs do not exhibit significant sexually dysmorphic characteristics. On average, male guinea pigs are slightly larger than their female counterparts, but a weight difference of a few ounces is not a conclusive measure of sex. Therefore, it is necessary to examine a guinea pig's reproductive organs in order to identify its sex.

The first thing you need to do is wash your hands before and after handling guinea pigs, as they can carry diseases that can also infect humans. At the same time, guinea pigs can also be affected by commonly used human products such as lotions, hand sanitizers, etc. Therefore, handwashing is essential to protect your health and that of your guinea pig.

Guinea pigs are often squeamish when lifted and held, so preparation prior to examination is important. Making sure your guinea pig feels relax and comfortable is critical. For young guinea pigs, handling them early can reduce their fear of people in the long run. Therefore, the earlier you get your guinea pig used to being handled by people, the better. Give your guinea pig a treat while you do this. This will make them easier to work with and less anxious.

You should hold the guinea pig gently but firmly, because it is easily frightened and often fights back. It is best to hold your guinea pig by the chest and shoulders so as not to frighten it.

When you can hold your guinea pig securely, place it on its back or hip so that its belly and genital area are facing you, and cradle the animal's back with one hand. This will make it easier for you to examine the guinea pig's genitals.

If you suspect your guinea pig may be pregnant, do not miss this other article on how to tell if a guinea pig is pregnant.

How to Tell the Difference Between a Male and Female Guinea Pig? - How to examine a guinea pig

How do I know if my guinea pig is male?

All guinea pigs, both male and female, have Y-shaped breasts and sex organs. However, male guinea pigs have a genital opening in the form of a small round tip with a penis that protrudes above the level of the surrounding skin.

Male guinea pigs have a bulge in their genital and anal area. The bulge is caused by the guinea pig's testicles, which are located just under the skin along the anus and penis and can be seen after two months of life.

Male guinea pigs have a larger distance between their penis and anus, about 2-3 cm.

How do I know if my guinea pig is female?

When it comes to sexing guinea pigs, is important to remember that both sexes have breasts, so this is not a distinguishing feature or characteristic of females. In other words, do not assume that your guinea pig is female based on this.

If you look closely at the guinea pig's genital opening, you will notice that female guinea pigs usually have a smooth swelling over their genital area. Use your fingers to gently open the genital opening. If the genital area is in the shape of a "Y", it means that the guinea pig is female.

Female guinea pigs have a smaller distance between their vulva and their anus. In female guinea pigs, the vulva often sits directly above the anus.

How to Tell the Difference Between a Male and Female Guinea Pig? - How do I know if my guinea pig is female?

When to separate a male guinea pig from a female?

In general, veterinarians discourage individual pet owners from breeding guinea pigs because breeding often shortens the life span of female guinea pigs.

If you breed a female guinea pig for the first time after she is 8 months old, this can be very dangerous as she may not be able to give birth to her young normally. Cesarean sections are rarely successful in guinea pigs, even when performed by an experienced veterinarian.

Neutering guinea pigs can be performed by a veterinarian experienced in handling small animals, but the procedure can be expensive and carries risks. The safest, easiest and least expensive way to prevent reproduction is to keep male and female guinea pigs separate.

Male guinea pigs (boars) are normally sexually mature and can mate as early as 2-3 months of age. Female guinea pigs (sows) normally become sexually mature at 2 months of age (55 to 70 days). However, males and females can be sexually mature and fertile earlier.

If you are sure your guinea pig is pregnant, we recommend you read this other article, where we tell you everything you need to know on how to take care of a pregnant guinea pig.

If you want to read similar articles to How to Tell the Difference Between a Male and Female Guinea Pig?, we recommend you visit our What you need to know category.

  • VIVAS TÓRREZ, JA Alternative species: guinea pig breeding manual . National Agrarian University, Faculty of Animal Science, Department of Veterinary Medicine. 2013. ISBN 978-99924-1-022-6. Available at:

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