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How to Introduce a New Pet Rat

Jessica worked in pet retail for over ten years. She adopted a light-sensitive albino leopard gecko (named Lewlew) in 2019.

Learn the step-by-step introductory process along with tips and personal insight.

Learn the step-by-step introductory process along with tips and personal insight.

How Do I Introduce My Rats to Each Other?

Rats make great pocket-sized pets for people of all ages. Rats are social animals and thrive with companions in pairs or groups. This is easy when buying or adopting rats from the same litter that have already bonded.

But creating friendships between new rats is not always simple. Rat owners sometimes need to introduce a new rat to an existing rat or group of rats. By following a step-by-step process, rats can be introduced safely and without injury.

Helping Your Rats Bond With a New Rat: Step-by-Step

  1. Quarantine the New Rat
  2. Place the Cages Side by Side
  3. Introduce Them in Neutral Territory
  4. Introduce Them in Familiar Territory
  5. House Your Rats in the Same Cage

1. Quarantine the New Rat

You should keep the newly acquired rat in quarantine for one to two weeks to avoid the transfer of disease. Quarantine means keeping the new rat in its own cage in a separate room without contact with other rats. This means washing your hands after handling the new rat before handling other rats. You also should not swap out items from the new rat's cage with anything from the resident rat’s cage. Illness can spread through this sort of contact. If you have many rats, this could result in unexpected and undesired vet bills. Some signs of illness to watch out for include:

  • lack of energy
  • not eating or drinking
  • discharge around nose or eyes
  • noisy breathing
  • excess sneezing
  • excess scratching

Watch for Red Nasal Discharge

During this time, you can still interact with your new rat, but keep an eye on their health. Is your newcomer’s nose wet, or crusted with red discharge? Rat noses are naturally dry, and wetness can be a sign of illness. Rats have sensitive respiratory systems and are prone to respiratory illness.

2. Place the Cages Side by Side

After quarantine, the next step is placing its cage side-by-side with the resident rat cage. The cages should be far enough apart that the rats cannot reach each other. This allows the rats to smell and see each other, becoming accustomed to each other. Sense of smell is a big deal to rats, and is much stronger than their eyesight. Rats have different personal scents, like any other animal. Female rats often “scent-mark” the cage, especially if another rat has urinated there. Sometimes rats will mark you because you smell like another rat!

Maintain This Placement for a Week

The rat cages should spend at least one week next to each other, every hour of every day. The rats need to become used to each other’s scents so the newcomer smells less like an impostor and more familiar. The rats should be curious about each other, sniffing and looking at each other. If one of your rats is showing aggressive behavior or hissing, proceed with caution. The rat may have an aggression toward other rats, and may be less likely to accept another cage mate.

3. Introduce Them in Neutral Territory

A few days after placing their cages together, you can have a play date between your resident and new rats. The first introduction should take place in neutral territory to avoid territorial behavior. Neutral territory is a place where your resident rat or rats do not usually play. A common compromise is the bathtub, but can also be the bed, the couch, or anywhere that the rats do not hang out. The bathtub was the best neutral ground for us, and should be harder for the rats to escape from. When having a first play date, have something soft (like a towel) along the bottom of the tub. Place plenty of tempting treats in the middle for the rats to share. Rats love treats, and eating them together is a great way for them to bond!

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Try the Glove Rat Method

There is a method on YouTube called the Glove Rat that helps when introducing new rats. It's great for when one or both rats seem jumpy, nervous or aggressive toward the other. In the video, a woman follows the rats around with a gloved hand while keeping close watch on their behavior. The goal is to deflect negative confrontation between the two rats, such as biting. If you get the sense that the rats are going to get into a fight, you place your gloved hand between them and break it up. The glove is there for your own protection, and makes the process feel less nerve-wracking.

Recognize Normal Dominance Behavior

It is normal for rats to express dominance by pinning, grooming, or or chasing each other around. The submissive rat will let out little “eeps” that sound like whispers, and mean that they "give up. Understand that this is normal rat behavior. Dominance is a big deal in rat colonies, and even rats sharing a cage will have scuffles over dominance.

Watch for Signs of Aggression

Watch out if a rat squeaks very loud or “screams” in pain, or if the rats are taking fighting to a level you don’t like. Some signs of rat aggression include:

  • pulling a rat's hair out
  • biting and drawing blood
  • swinging it's tail around
  • hissing at other rats

Watch the play date and follow your gut. If you think one of the rats is taking it too far, separate them. And the first few play dates should be short. Fifteen minutes is enough for the first few days, and you can introduce them as many times as you prefer each day. As the days pass, the rats should know each other more and be less nervous. If you have an aggressive rat on your hands, give them some space before you try again.

4. Introduce Them in Familiar Territory

Once your rats are making progress, you can introduce them in familiar territory. Familiar territory is a place where the resident rat likes to play on occasion. This is different because your resident rats will feel territorial about their location. This place can be the bed, the sofa, or anywhere your resident rat might consider their own.

The interactions between the rats here can be more tense than in neutral territory. Having keen eyes and using a gloved hand are very important in familiar territory. Your resident rat may feel the need to guard their territory, and more dominance fights may occur. Watch that neither rat is aggressive toward the other. If behavior escalates to a violent level (or if you feel the need to separate them), end the session. You can always give it another try later.

5. House Your Rats in the Same Cage

When your rats have bonded enough to share a cage, you can do one of two things. You can house the rats in a brand new cage, or move them into one of the cages either rat has been living in. Moving the rats into a preexisting cage involves a lot of cleaning, rearranging, and time. Save this step for a day when you plan on being home so you can watch the rats. And if you do it in the morning when your rats are sleepy, it can ease the process.

Need a new rat cage?

Prepare the Cage

You’ll need to clean the cage from top to bottom, throwing out all the old bedding and food. Use a pet cage cleaner from the store that both cleans and deodorizes the cage, and be as thorough as possible.

After wiping down the cage and any other objects inside, rearrange everything:

  • If you have a multilevel cage, move the shelves around.
  • Change where the food and water are located, as well as any detachable ledges or other objects.
  • If you have hammocks like my rats do, wash them and re-position them.
  • To help disorient the resident rat, add new toys and accessories to the cage that neither rat has seen.

The cage needs to look new to both the resident rat and the newcomer. It cannot smell like the resident rat, or they will defend it like it is their territory. Once this is all done, you can let the rats explore.

Rats often play and scuffle by boxing, where they literally look like little boxers!

Rats often play and scuffle by boxing, where they literally look like little boxers!

Expect a Few Scuffles, But Hopefully the Friendship Will Develop

As with the play dates, expect more dominance scuffles started by either rat. If the process has gone well, the rats will eventually become good friends. The struggle for dominance will always be present, as one rat will always seek to be dominant. Wrestling and boxing are ways that rats like to play, so don’t worry unless you spot injuries or if a rat vocalizes pain.

Remember: In the end, it comes down to your gut. If you feel the rats aren't being friendly, then they may need more time apart. The truth is, most rats enjoy companionship and can become best friends over time.

This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.

Questions & Answers

Question: My two-year-old rat had to be put to sleep. Now his littermate looks lost on his own. How long should I wait to get him a friend? Also, all the rats I can find are twelve-weeks-old. Is this too much of an age gap?

Answer: Not necessarily. A lot of adults rats are accepting of younger cage mates! Every rat is different though, so you would have to watch your adult during intros to see how he reacts. Sometimes introducing two older adult males can be more difficult due to territorial behavior. I wouldn't say there's a specific waiting time before finding him a new friend. Just be diligent during intros - having your hand close by your adult can help in case you feel you need to stop interaction fast.

Question: Introductions with my boy rats were going well, but when I moved them all into the cage together there was a lot of fighting and even shrieking! They were a big happy family in neutral spaces and everything in the cage was thoroughly cleaned, did anything go wrong?

Answer: Boys are not as accepting as girls when it comes to sharing a space. I had my boys separated for two weeks due to a medical procedure, and had to reintroduce them back into the cage together. I broke up a fight that I didn't like (they were rolling around and squeaking) and spent a day monitoring them before I let them stay together. I took out a ramp that they were fighting over, and now they are keeping their distance when they don't want to be bothered. You can keep trying/backtrack a step and try again. Sometimes it's just a matter of dominance. Some owners of male rats get them neutered or get the most aggressive boy neutered to tame his behavior.

Question: I have had two male rats (brothers) that I have had from about 8 weeks old. Sadly one has recently passed away at around 18 months old. I am really conscious of leaving the survivor as a lone rat as he is used to company. I am considering getting one or two baby male rats to give him some company. Will this work or will he be better living alone now?

Answer: Rats are very social, and do get depressed if suddenly left alone. Considering he is only 1.5 years old, getting him companions would be ideal. I would do two new rats, so that you are not facing the same situation in 1-2 years. The decision is ultimately yours, however.

Question: I've never introduced a baby to an older rat until today and didn't do my homework. I just put a six-week-old baby in the cage with my older one-year-old female. They are both females, and my older rat is very aggressive, and I don't own a second cage. Do I just keep a close eye on them, or do I go purchase a cage and do the introduction the long way?

Answer: I would get a second cage to keep the new rat in while you do introductions. I've even used an old birdcage after zip-tying the food and water access doors down. While your rats could end up getting along, throwing them together in a cage where your older has been dominant and alone until now could result in aggressive behavior. And unless you can watch them 24/7, you could easily miss a moment where you would need to intervene on behalf of the younger rat.

Question: I got two rats about a few months ago, and they have been together since they were small babies, so they are used to each other. I was thinking about getting another baby rat, but I don’t know how the other two rats would react to the new baby. I only have a small cage so the baby wouldn’t be able to stay in the cage for long. I’m scared the other two might not like the new rat. What do you think I should do?

Answer: Younger rats are more likely to accept a new cage mate than adults, so it may work out just fine! Even if the temporary cage for the new rat is small, it would only be in there until introductions are complete. You won't really know until you try, but since they are still young, they may accept a new rat well!

Question: I had 2 females, aged around 2 1/2 to 3 years. In May, my more outgoing girl had an unexpected stroke, and she passed away. I am now left with 1 girl who is very timid, she doesn't love being handled, and freaks out when not inside cage. I would LOVE to get 4 young girls, but I worry that my current will either be picked on or may be mean toward the newbies out of fear. How should I go about introducing the dogs in this situation? Are there other methods that can be used to reduce my oldie's stress?

Answer: Can you lure her out with treats, maybe something especially appealing like tuna, peas, etc? If she loves treats, maybe you can get away with her having a lot of snacks during intros with potential new girls.

Question: Can a two-year-old rat become friends with a two-month-old rat?

Answer: Absolutely! Has the two-year-old ever had a rat companion before? That would definitely help with introductions. If the rat has been alone its whole life, you may have to take introductions more slowly, as the rat will have never known companionship before. It isn't guaranteed that the two rats will get along - aggressive rats do exist - but most rats enjoy having company.

Question: I have a rat that's about six-months-old and my friend just gifted me a little guy that seems maybe two-months-old at most! The size difference alone makes me nervous about an introduction. Will an older male rat be more accepting of a younger rat or do I need to be worried more than usual?

Answer: All rats are different, but most of them are accepting of a cage mate. Your older boy is technically an adult at six months! He may be fatherly toward the younger one, but it's hard to know without intros. You can try taking the process really slow and seeing how they both react. If at any point you feel uncomfortable with how things are progressing, you can stop or take a step backward.

Question: I have a 2 year old male rat who just lost his cage mate. I bought two 4-6 week old male rats and introduced them two days ago. The older rat shows no aggression, they cuddle together, the babies crawl all over him and groom him and hide under him. I have left them in the same cage for about 12 hours now and they have not had a problem and mainly sleep and cuddle next to each other. Is it safe to leave them overnight, or is better to separate them until the babies get older and bigger?