Trying to figure out if you should get a male or female guinea pig? The differences go well beyond anatomy, and even pet store employees sometimes get it wrong on young piggies.
Males (boars) weigh up to 2.6 pounds and are more territorial. Females (sows) top out around 2 pounds and are calmer in groups.
Here are the ten biggest differences between the two.
10 Differences Between Male and Female Guinea Pigs
Why Is It Important To Know The Gender Before Buying?
The right name is one reason, but there’s a bigger one. You might buy two “females” that turn out to be a male and a female, and suddenly you’ve got a surprise litter on the way.
Don’t blindly trust pet store sellers. It’s often difficult to determine sex with 100% accuracy in small piglets.
Even experienced veterinarians make mistakes at such a young age.
This matters especially if you have several guinea pigs and don’t plan to breed them. Guinea pigs become sexually mature at 6 to 8 weeks (some even earlier), so they’ll start mating if you don’t separate them.
That’s why it’s important to separate males from females about three to four weeks after birth.
Living With Another Guinea Pig
When male guinea pigs share a cage, constant games and competitions occur that can end in fights and injuries. It’s not recommended to keep two or more males together because the chance of fighting goes up.
Female guinea pigs get along well with other females, but rare fights can still happen. Keeping three or more females in one cage increases the risk of aggression over time.
If you want two pigs, buy same-sex animals. For those who want to breed, keep the male and female in different cages and only put the female with the male during mating.
Otherwise, you’ll end up with an unplanned pregnancy.
Who Is Better, a Boy or a Girl?
Guinea pigs are highly social, so it’s best to keep them in pairs or groups. Most owners keep a pair of the same sex, or just one pig with plenty of human interaction.
Males are bolder and more curious, so they’ll require more attention. They’re a great choice for kids who have time to play.
Just keep in mind that males can fight for dominance when kept together.
Females are more cautious and less demanding of your time. They’re a solid pick for owners who can’t dedicate as many hours to daily interaction.
Difference of Genitals Between Males and Females
Guinea pigs don’t like to lie on their backs for long, so you’ll have limited time to check. If your pig squirms, ask someone to help hold it, or offer a treat as a distraction.
Female genitals usually have a smooth swelling in the genital area. Use your fingers to spread the opening gently.
If it’s Y-shaped, V-shaped, or a vertical slit, it’s a female.
Males have a genital opening in the form of a small round dot with a penis that protrudes above the surrounding skin. The foreskin is raised and rounded, like a button or dome.
If you press lightly above the genital opening, males will show a penis. A ridge over the genitals is a clear sign of a male.
If you also find testicles on either side of the penis, there’s no doubt.
In male guinea pigs, the testicles don’t sit in a convex sac like in most other animals. They’re too large for the small patch of skin between the anus and penis.
Instead, they sit just under the skin on each side.
This arrangement causes the genital and anal regions to bulge outward. You can feel a hard, smooth testicle under the skin that moves freely.
The guinea pig can retract its testicles into the abdomen if it wants to.
Aggression in Male and Female Guinea Pigs
A female who’s unhappy with courtship will defend herself from an annoying male. Her typical response is to spray urine at him and run.
She usually succeeds because the male pauses to sniff himself.
Several energetic jumps from an angry female can also discourage a male from flirting. A sign of reconciliation is when a pig exposes the most delicate parts of its body, like the muzzle and neck.
The pig stands on fully straightened paws and throws its head up. This pose is adopted by submissive individuals and males toward their partners.
Many animal species behave similarly.
Guinea pigs feel best in a group. Keeping multiple piggies lets you observe their herd behavior, which only shows up when they feel safe.
A lone guinea pig needs lots of human attention so it doesn’t feel lonely.
Smell Difference Between Genders
There’s a common misconception that male guinea pigs smell more than females. In reality, if your pig lives in a clean environment, neither sex has a pronounced unpleasant odor.
Bad smells usually come from dirty bedding, not the pig itself.
Males do have a “fecal pocket” that contains a whitish lubricant with a specific smell. The male keeps this pocket closed normally, so you won’t notice it.
A healthy male handles the hygiene of this area on his own.
During courtship, though, the male opens this pocket wider, and that’s when the smell becomes noticeable. Two males meeting for the first time may also display courtship behavior toward each other.
This is accompanied by a characteristic rumbling sound.
Once they’ve established a hierarchy, the courtship behavior stops. In long-haired breeds, males tend to have a cleaner coat at the back, while females can get messier.
This is because females pee downward and males pee forward into the litter.
Weight and Size
A guinea pig’s weight is one of the most important indicators of its well-being. If you track your pet’s weight over time, you can spot unusual changes early and take action.
In the first months of life, guinea pigs gain 30 to 50 grams per week. The gain gradually slows and stops around 12 to 14 months.
During this period, males become noticeably larger than females.
Females are usually 20-25% smaller than males. Males weigh 0.9 to 1.4 kilograms with a body length of 30 to 35 centimeters.
Females weigh about 800 to 1200 grams and are 20 to 25 centimeters long.
Size depends on age and breed, so it’s not a 100% reliable way to determine sex. Use it as an extra indicator alongside other methods.
After reaching one year of age, adult males weigh 0.9 to 1.4 kg and females 700 to 900 grams. If your pig’s weight falls slightly outside these limits, that’s not a cause for concern.
Some guinea pigs are just naturally bigger or smaller. If you have any doubts, consult your veterinarian.
What Are the Differences in Baby Guinea Pigs?
In baby males, a small tubercle is visible from the retracted penis. In females, the genitals show a triangle shape.
Males also have more skin folds in the genital area than newborn females.
You can also watch their development to tell them apart. Until one week old, babies of both sexes develop the same way.
After the first week, boys start growing and gaining weight faster than girls.
Appearance Differences Between Males and Females
You can tell males and females apart by their external features and behavior. Girls are smaller and more graceful, weighing 1 to 1.2 kilograms.
Males have slightly more massive heads.
Due to an odorous gland in the anal sac, male feces have a sharper smell than female feces. Males also behave more aggressively and tend to show dominance, which is especially obvious when both sexes share a cage.
Females are calmer and friendlier. They only show aggression in rare cases, like protecting their cubs.
When kept together, males constantly compete for food, territory, and females. They can start noisy fights, though they rarely cause serious injury.
Calm girls will get along well in one cage, share food, and even sleep in the same house. Males are more talkative and show emotions with loud rumbling or displeased hooting, while girls tend to sleep or rest most of the time.
At What Age Are Gender Differences More Visible?
You can’t tell male from female right at birth because their bodies are too small. It’s important to wait before examining their genitals.
After about two weeks, when weaning usually occurs, you can start to see the differences with the naked eye. But mistakes are common even among experienced caretakers, since not all animals develop at the same pace.
If you’ve just adopted a small guinea pig and don’t know the gender, take it to the vet. This is especially important if you already have an adult female and want to avoid an unplanned pregnancy.
When Do Males and Females Reach Puberty?
Females usually reach puberty between three to five weeks of life. Males take a bit longer, with the average being four to six weeks after birth.
Just because they’ve reached puberty doesn’t mean you should breed them right away. Experts recommend waiting around two months for males and five months for females before breeding.
Final Thoughts
Knowing whether your guinea pig is male or female matters more than you’d think. It affects housing decisions, social pairings, and whether you’ll end up with a surprise litter.
Both boars and sows make great pets. Pick the one that fits your household, and give it the attention and companionship it needs to thrive.
Frequently Asked Questions
Two males can live together peacefully if there are no females nearby. Introduce them on neutral territory and give them a spacious cage with multiple hideouts. There'll be some dominance posturing at first, but most boar pairs settle down once they've established a hierarchy.
Females are generally calmer and less territorial, which makes them easier in group settings. Males are more outgoing and interactive with their owners, though. Both sexes can be affectionate once they've bonded with you, so friendliness depends more on the individual pig.
Check the genital area carefully. Females have a Y-shaped or V-shaped opening, while males have a round dot with a slight protrusion. It's easiest to check after two weeks of age. If you're unsure, a vet can confirm the sex quickly.
Separate them by three to four weeks of age. Guinea pigs can become sexually mature as early as three weeks, and an accidental pairing leads to pregnancy fast. Keeping them apart early prevents surprise litters and reduces stress for both pigs.
