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Why Do Guinea Pigs Bite Each Other’s Bums?

Have you noticed that your guinea pig likes to sniff or bite other guinea pigs’ bums? Guinea pigs may bite at each other’s bums for many reasons, but it does not mean it is a bad thing. 

This behavior can be characterized by several factors, from bonding with new cage mates to lack of nutrition or stress. 

Knowing the norms and abnormalities of guinea pig behavior can be essential to determine if and when to intervene. 

Continue reading to learn how to differentiate between biting each other’s bums for playful reasons or something else. 

Why do guinea pigs bite each other’s bums? (3 reasons)

Witnessing your guinea pigs biting each other may be concerning, but being able to tell if it is normal behavior or not can be imperative. 

If guinea pigs are not behaving normally, they could be sick or stressed. These are the most common reasons why guinea pigs may bite at each other’s bums. 

Do not worry; we will cover the most common reasons for biting, both playful and fighting. 

Normal behavior

Typically, biting or sniffing each other’s bums is entirely normal. Guinea pigs are extremely curious and usually enjoy residing in pairs or groups. 

Their behavior, including biting each other’s bums, helps to determine their social rankings within the pair or group. 

This is also a form of bonding and getting acclimated to new surroundings. 


Sometimes, dominance can appear aggressive and include behaviors such as biting, scratching, squealing, or worse. 

This is most common when a new cage mate is introduced, and they are figuring out their social cues. 

However, this behavior will eventually stop when they become aware of and comfortable with the new arrangement. 

Stress or lack of nutrition 

Guinea pigs may also show odd behavior when they are stressed or sick. They may be acting out due to discomfort or lacking nutrients in their diet. 

Bum sniffing or biting may insinuate that they are searching for nutrients that may be found in their cage mate’s feces. This can cause stress if it is affecting their health. 

They may also stop eating and drinking normally. Consult with a veterinarian if you are concerned that they may be sick. 

How to tell if guinea pigs are playing or fighting?

How to tell if guinea pigs are playing or fighting

If you realize that your guinea pig’s biting behavior is no longer due to dominance or socializing, they may be incompatible. 

When playing becomes harmful to either guinea pig, it may result in injuries, sickness, or death. Knowing the differences can help you learn about your guinea pigs’ personalities and if their behavior is normal. 

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Observe your guinea pigs’ behavior with caution and use protection whenever breaking up a fight. 


Guinea pigs can cause serious injury with their nails or teeth. If guinea pigs have a history of fighting, especially causing injury, they should not be housed together. 

Injuries can cause infection, sickness, or even veterinary visits. Be careful when determining if the guinea pig can be reintroduced to either previous cage mates or new ones. 

A guinea pig can be caged alone and still live a happy life. If you have any questions or concerns, it is always best to consult with a veterinarian. 

Lack of equal access to food and water

Guinea pigs may fight for many reasons that do not pertain to their personality or gender. 

When more than one guinea pig is housed together, they should each have their own cover, water bottle, and food bowl to avoid jealousy or lack of food and water.

Playful behavior

Guinea pigs like to chase each other and play hide and seek as a form of entertainment. They may squeal, sniff or bite each other’s bums, or walk nose-bum throughout their enclosure. 

This is usually not a cause for concern unless they draw blood and fight aggressively. 

Should you intervene if guinea pigs are biting each other’s bum?

Should you intervene if guinea pigs are biting each other’s bum

You may need to intervene if you notice that your guinea pigs are causing injury, not eating or drinking, or the dominance phase doesn’t appear to end. 

Since guinea pigs’ teeth and nails are sharp, they can cause injury to you while breaking them up. There are some steps to take if you find yourself in this situation without causing more damage. 

If you intervene, it may be time to decide if it is time to separate them temporarily or permanently. 

Use a towel or thick gloves

If you have to separate the guinea pigs, use a towel or thick gloves to protect yourself from injury. This will help create a space to safely separate them and keep your skin covered. 

Keeping them in different areas is important so they cannot see each other. 

Loud clapping, separation 

To break up a guinea pig fight, clap your hands loudly or make loud noises to startle them. This will help them separate and stop fighting. 

They most likely will find their favorite hiding spots until they feel it is quiet and safe enough to come out again. 

However, seeing the other guinea pig may trigger them to begin fighting again. It is best to separate them safely. 

Time-out scenario

If your guinea pigs are aggressive towards each other, they may need to be temporarily separated. Using a cage divider or a separate cage ensures the guinea pigs cannot reach each other and cause further injury. 

Some guinea pigs may be able to return to living together based on the severity of the injury. Guinea pigs with a history of fighting may be risky to house with other guinea pigs. 

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It may be safest to separate them permanently. You can keep them in separate cages but still next to each other for interacting vocally.

How do guinea pigs behave around new cage mates?

How do guinea pigs behave around new cage mates

If your guinea pig is nipping at the other’s bum, it is telling the other guinea pig they are in charge. It will continue until the less dominant one succumbs, or gives up and allows the other to dominate. 

However, this behavior may become more dangerous and even mean that the guinea pigs should be temporarily or permanently separated. 

It is never guaranteed that any two guinea pigs will get along. If this applies to you, continue to read about if this new cage mate behavior is normal. 


Guinea pigs will be in the most common position for fighting when they initially meet another guinea pig. 

Introducing guinea pigs for the first time can properly be done by allowing short time intervals together and using a divider if necessary. 

This keeps them within reach of smelling and seeing each other, but not allowing them to potentially cause any injury. The guinea pig’s age may be a factor and if they have lived alone or with other guinea pigs before. 

It may be helpful to understand a guinea pig’s history with previous cage mates or if it is used to living alone, to prevent any issues. 

Male and female guinea pigs housed together

Male and female guinea pigs housed together are likely to result in a pregnancy as guinea pigs are extremely active and easy to mate. 

Dominance can occur between guinea pigs of either gender, which includes mounting and biting each other. 

Knowing the behavior of mating guinea pigs, or of the same gender, will help you determine why. 

Socializing and bonding 

Most guinea pigs can determine social rank and dominance within a week or two. If the behavior is concerning, causes injury, or lasts longer, it may be time to determine if other factors are involved. 

Socializing guinea pigs is important as they are animals that tend to live in pairs or groups. Once they are socialized and bonded, they do not tend to bite each other, unless something else is wrong. 

Final thoughts

Guinea pig behavior can be interesting, but knowing the difference between being playful and fighting behavior can be key to a happy living situation for all involved. 

Biting each other’s bums can be a sign of dominance, stress, or playing, so it is important to be able to distinguish the difference and if there is a need to intervene. 

In most instances, bum sniffing and biting are normal behavior, but if it appears aggressive, you now know what to do to break up a fight or separate them. 

As always, consult your veterinarian with any other questions or concerns.