How to Introduce a New Pet Rat

Updated on July 5, 2015
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Dreamhowl has worked in pet retail for over ten years. She has owned fancy rats, and has experience with small pets, fish, and dogs.

Rats make great pocket-sized pets for people of all ages. Because of their social nature, rats should be kept in pairs or groups so that they enjoy constant companionship. This is easy when buying or adopting rats from the same litter who have already bonded; however, creating friendships between new rats is not always simple. Sometimes, a rat owner needs to introduce a new rat (or multiple rats) to an existing rat or group of rats. By following a gradual, step-by-step process, rats can be introduced without significant injury. This hub focuses on the introduction of a new female rat, Gadget, to the resident female rat, Patches. Interactions between male rats may not be similar.

Please note: Not all rats, male or female, will take to another cage mate. There are some rats that simply want to live in their territory alone. If attempting a slow introduction through small steps does not improve the relationship or aggression either rat experiences, do not force it. Aggressive rats can cause serious harm to one another if they view one or the other as a threat.

We introduced Patches - the resident rat - to a new rat so she wouldn't be lonely.
We introduced Patches - the resident rat - to a new rat so she wouldn't be lonely. | Source

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1. Quarantine the new rat

When acquiring your new pet rat, professionals suggest that your keep the newcomer in quarantine for one to two weeks before allowing it near your other rats to avoid the transfer of disease. What does this mean? Essentially, quarantine entails keeping the new rat in it’s own cage in a separate room without any possible contact with your other rats. This means washing your hands after handling the new rat before tending to your older residents and not swapping out items from the newcomer’s cage with anything from your other pet rat’s cage(s). Illness can spread quickly through this sort of contact. If you have multiple rats, this could result in many 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

During this period of time, you can still interact with your new rat and establish a relationship, but keep an eye on the rat’s health in the meanwhile. Is your newcomer’s nose wet, or crusted with red discharge? Rat noses are naturally dry, and wetness can be a sign of illness. Rat’s have sensitive respiratory systems and are more prone to respiratory illness than other animals. An excess of red mucus around the nose and eyes may simply be a sign of stress, especially after moving to a new environment, but can signal to illness if constantly present. Do not confuse the red mucus with blood, but keep an eye on it all the same.

Note: I did not put Gadget through the quarantine, but only because I have had my eye on her long before I purchased her at my current place of work. During this time, she had constantly been with other rats in the small animal display, and was picked on - not ill.

We put Gadget - the newcomer - in a temporary cage while she bonded with Patches.
We put Gadget - the newcomer - in a temporary cage while she bonded with Patches. | Source

2. Place the cages side by side

After the quarantine period, the next step to introducing the new pet rat is placing its cage side-by-side with the resident rat cage. The cages themselves should be just far enough apart that the rats in each cage cannot reach out and touch each other (especially their tails). This allows the rats to smell and see each other and thus become accustomed to each other. Sense of smell is a big deal to rats, and is much stronger than their eyesight. Like people and other animals, rats have different personal scents; when female rats are housed together, you will often catch them “scent-marking” in different areas of the cage, especially if another rat has urinated there previously. Sometimes rats will mark you because you smell like another rat!

Did You Know?

Did you know that you can help introduce your rats by letting them run around in the other's cage? Letting each rat explore the other's smell helps it become a familiar scent, and helps them become better friends!

The rat cages should spend at least one week next to each other this way, every hour of every day. It is important that the rats become used to each other’s scents so that the newcomer smells less like an impostor and more familiar. If anything, the rats in both cages should be curious about each other, sniffing and looking at each other and sometimes showing excitement. If your resident or new pet rat is instead showing aggressive behavior or hissing, proceed through the following steps with caution. The rat may have an aggression toward other rats, and may be less likely to accept another cage mate.

By sharing delicious tuna, Patches and Gadget bonded in familiar territory.
By sharing delicious tuna, Patches and Gadget bonded in familiar territory. | Source

3. Introduce them in neutral territory

A few days after placing their cages together, you can continue by having a play date between your resident and new rats. To minimize territorial behavior on behalf of the resident rat, the first introduction should be done in neutral territory - a place where your resident rat or rats do not usually play. A common compromise is the bathtub, but can be the bed, the couch, or anywhere else that the rats do not hang around. The bathtub was the best neutral ground for us, and should (theoretically) be harder for the rats to climb out of or escape than a sofa. When having a first play date, be sure to have something soft, like a towel, along the bottom of the tub, and 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.

There is a method on YouTube called The Glove Rat that works great when introducing new rats, especially when one or both rats seem jumpy, nervous or potentially aggressive toward the other. In the video below, a woman essentially follows the rats around with a gloved hand while keeping close watch on their behavior. The idea is to deflect any negative confrontation between the two rats that has the potential to ruin their relationship, such as biting and scratching. If you get the sense that the rats are going to get into a fight of aggression, you quickly 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.

See the Glove Rat in Action!

It is normal during play dates for the rats to exert dominance on one another in the form of pinning each other down and forcefully grooming the other, pushing the other rat away or chasing them around. During these situations, the submissive rat will let out little “eeps” that sound low, like whispers, and simply mean that they give up. All of this is normal rat behavior - dominance is a big deal in rat colonies, and even rats sharing a cage will have scuffles over dominance. You should be concerned if a rat squeaks very loudly, or “screams” in pain, or if the rats are taking their 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 closely and following your gut. If you think one of the rats is taking it too far, separate them. The first few play dates should be relatively 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 need to be separated less. If you have an aggressive rat on your hands, give them some space for a while before you try again.

Note: after a while, Patches (who has ninja-like reflexes and moves) learned that she can pounce out of the bathtub. If you can't keep your rats in the tub either, you can introduce them anywhere neither of them has played before - kitchen counters work, as well as tables. It's up to you.

The bed has become a place of familiar territory and playtime for my two rats.
The bed has become a place of familiar territory and playtime for my two rats. | Source

4. Introduce them in familiar territory

Once you feel your new and resident rats are making progress, you can start putting them together in familiar territory - a place where the resident rat likes to play on occasion. This is different from the previous step because your resident rats will feel partially territorial about their play date location. This place can be the bed, the sofa, or anywhere your resident rat might consider their own. The interactions between the rats here may be more tense than in neutral territory, so having keen eyes and using a gloved hand are very important here. Your resident pet rat may feel the need to guard her territory, and more dominance fights may break out than expected. Be sure to watch that neither rat is injured or overly aggressive toward the other; if the behavior escalates to a violent level (or if you feel the need to separate them), end the session for a little while and give it another try later.

Tip: If play dates in the resident rat’s territory aren't going well, take a step backward and have the sessions on neutral ground again. You can repeat this until you feel the rats can move up to the resident’s territory again, as many times as you feel necessary. Depending on your rats and their personalities, this step can be simple or take a few tries.

At the end of the day, Patches and Gadget snuggled together in the same cage.
At the end of the day, Patches and Gadget snuggled together in the same cage. | Source

5. House your rats in the same cage

When your new and resident rats have bonded enough to share the same cage, you can either put them in a brand new cage, or move them into one of the cages either rat has been living in during your introductory phases. It is more economical to move them into a preexisting cage, but this step involves a lot of cleaning, rearranging, and time. It is best to complete this step on a day when you plan on being home and can monitor the rats, as well as in the morning when your rats are sleepiest.

Note: For this step, I cleared off the bed and let the rats play while I cleaned, having a towel, play tube, toys and treats on-hand to keep them occupied. I decided to house both rats in Patches' cage, knowing that I would need to clean the smell out entirely and make it seem new and unfamiliar.

You’ll need to clean the cage from top to bottom, throwing out all the old bedding and food. Use a pet cleaner from the store that both cleans and deodorizes the cage, and be as thorough as possible. After wiping down the entire cage and any other objects (such as a running wheel or an igloo that you plan on keeping in the cage), 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. Essentially, the cage needs to look new to both the resident rat and the newcomer. It cannot smell like the resident rat, or she will defend it like it is her territory. It helps to disorient the resident rat by adding new toys and accessories to the cage that neither rat has seen. 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! | Source

As with the play dates, expect more dominance scuffles started by either rat. If the introductory process has gone well, the new cage mates will take to each other eventually, but at the very least behave around each other. The struggle for dominance will always be there, as one rat will always seek to be dominant in their surroundings. Wrestling and boxing is a common way that rats like to play, so don’t be too concerned unless you spot any injuries or if a rat vocalizes her pain.Remember: In the end it comes down to your gut. If you feel the rats aren't being friendly, then maybe they need some more time apart. The truth is, most rats enjoy companionship and, over time, can become best friends.

Note: As of the present date, Patches and Gadget have been living together for over a year, and act like new friends. Sometimes Patches needs her space, but the cage is big enough for them to be apart when they want to, and be together, too.

Questions & Answers


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      • Dreamhowl profile image

        Jessica Marello 3 months ago from United States

        @Brendan Did you clean the cage thoroughly beforehand, and moving the items inside the cage around? That can help Pistachio feel like they are in a new cage that doesn't "belong" to them. It also could have been a common dominance fight - my first two girls used to "box" each other while standing on their hind legs often.

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        Brendan 3 months ago

        I’ve had Cashew for about 2 weeks now(medium rat) and pistachio(large rat) near each other. I put cashew in pistachios cage and they started fighting? There was squeaking and they both stood on their hind legs. I broke it up because cashew is much smaller than pistachio. I know they stand up like that when they actually fight but I could not tell.

      • Dreamhowl profile image

        Jessica Marello 3 months ago from United States

        @Hannah Patches was at least five months old (if not more) and Gadget was a couple of months - she had been sitting at our store for a little while, getting passed over. I think you'll be fine introducing a new female rat to Remi, as long as you take it slow. Being younger might help with introductions, but Gadget wasn't a tiny baby when we got her, and it still worked out.

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        Hannah 3 months ago

        How old was Patches and Gadget when you introduced them? Currently I have a 5 month old female rat, Remi, and I didn't get her a companion when we originally bought her because the vet told me she was a male. Now that I'm 100% confident Remi is a girl, we want to get her a sister. Does the younger they both are help with introductions?

      • Dreamhowl profile image

        Jessica Marello 8 months ago from United States

        @Aj That's exciting! I hope your introductions all go smoothly.

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        Aj 8 months ago

        I have had a girl rat lily for a month and I am getting another one for her to have a companionship this was really helpful to me. Now I know how to introduce my new rat when I get her.

      • Dreamhowl profile image

        Jessica Marello 12 months ago from United States

        @Sherry I just saw this! You're welcome - I'm glad this could help you.

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        Sherry 13 months ago

        Thank you so much for this. We had two rats, Iris and Zaya, but last night Zaya died quite abruptly and I was looking to see how to introduce a new one. I would personally like a little more time to be sad but I know that Iris really needs a companion so we will probably get one from the same breeder tomorrow. Thank you for this great advice!

      • Dreamhowl profile image

        Jessica Marello 13 months ago from United States

        @Teagan I'm sorry for your loss. It's a really decent cage for the price! It also held up pretty well - I only had to replace it once when my (bratty) rat ate a hole through the plastic base. Had to get a little creative to keep her from doing it again.

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        Teagan 13 months ago

        Hello! This is very useful. One of my boys died and we had only two. So now one is left. We had bought him a friend, but the new one ended up being a girl. So now we have to get her 2 babies to go with her and him 2 boys to go with him. I also noticed that you have the same cage as I do! Really cool.

      • Dreamhowl profile image

        Jessica Marello 17 months ago from United States

        @Lisa That's wonderful! So relieved they are getting along now. I remember how happy I felt seeing my first two rats cuddling in the cage for the first time. I'm sorry one of your rats passed away, though - it's a rough thing.

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        Lisa 17 months ago

        AH MAZING!!!!! Thank you so very much!!!! This worked!

        My two daugher's each had a female rat who live together for 11 and then the one who belonged to my younger daughter (10 yro)passed away due to respiratory issues.

        My husband felt bad and went and bought her a new rat the very same night and put the new littler rat right into the cage. It did NOT go well at all!!!

        The resident rat is larger and bullied the new rat all night. Isis(the resident rat) was coming up to the new rat Pancake huffing at her, pushing the bedding up towards her & tried to bite her. She also took all the food from her and even out of the food bowl downstairs, upstairs to a corner to hide it just so Pancake wouldn't have any!

        My oldest daughter tried to detour Isis by squirting her with a water bottle, which worked until we weren't looking. It was a very long night for everyone!

        I was stressed, both rats were stressed, my kids were stressed!

        Then next morning I found this article!!! It worked and within 2 days!

        I did the bathtub trick and that went great, so I washed out the 3 tier cage, rearranging it, washed all the bedding & now they are sleep TOGETHER in the same bed

      • Dreamhowl profile image

        Jessica Marello 17 months ago from United States

        @debi166 Hey, I'm not sure if I mentioned this in my hub completely: have you tried feeding them tuna during their time in neutral territory? What I remember doing was having tuna out on a plate (like in the picture) for them to snack on. But I also took some of the water that comes in the tuna can and dabbed it at the base of their tails. I had read that it helps mask their own personal scent. Suddenly the new rat smells like the old rat! And hopefully they'll be so focused on tuna that the dominant girl doesn't get so worked up. Maybe try it one session and see if it helps at all?

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        debi166 17 months ago

        We are having a problem with a dominant rat, we recently got a new rat because one of our two resident rats is sick and I didn't want the other to be alone if we lose the sick one. The dominant rat is a little over a year old and the new rat is probably around 4 months old. Our first introduction went bad very quickly, the new rat was bit right away. So we took a few steps back and have been socializing on neutral turf which sometimes go well then other times Tyanna (dominant rat) puffs up and goes after the Lotti (new rat). Lotti yells but I break it up right away.

      • Dreamhowl profile image

        Jessica Marello 2 years ago from United States

        @Chloe I've never had a pack of three before, but I would just keep an eye on them for a little while. Are they in the same cage yet? A healthy amount of dominance fighting is okay - like you said, it's to be expected. There will always be dominance scuffles, like wrestling, boxing, pinning, or even mounting. But if it seems like the little one is being bullied, is shrieking like she is in pain, or blood is drawn, something is definitely wrong. My first pair used to fight and box a lot more than the girls I have now, but they still pin or mount each other from time to time.

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        Chloe 2 years ago

        Hello..I bought my first rat at the beginning of the year and shortly after found her a friend to keep her company! They were 10 weeks and the second 14weeks old. They got on well and live together perfectly since the start but we've just brought home a new little 8 week female and our two are around 4 months now what should I look out for? They seem calm and they cleaned her but I know to expect dominance fighting where do I draw the line that it's not working out? I don't want to make our new little baby uncomfortable at all but I don't want to mess up their natural instincts if they've supposed to fight etc please help!! X

      • Dreamhowl profile image

        Jessica Marello 2 years ago from United States

        @Klae I'm glad it's been helpful! Just take your time and don't rush it. I hope they take to each other soon.

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        Klae 2 years ago

        Hi! I found this super helpful because I'm currently in the process of introducing a baby female (9wks) to my older female (1.5yr) and its been lengthy - plus it makes me so nervous when I hear the small one making squeaks! I hope they'll be the best of friends, I felt terrible about having my lone female for a while.

      • Dreamhowl profile image

        Jessica Marello 2 years ago from United States

        @Kim It's a little belated, but I'm glad I could help!

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        Kim 2 years ago

        Love the article! I'm currently getting a new rat used to my older rat. The process is going good. It's nice to know what is playing and not actually fighting. Thanks for the help!

      • Dreamhowl profile image

        Jessica Marello 5 years ago from United States

        Thank you for reading! Believe it or not, you do need an introductory process for pet rats that aren't from the same litter; just like with other pets, they won't always get along. Thanks again!

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        Adrienne F Manson 5 years ago from Atlanta

        Hi Dreambowl, I was reading your article and glaring at the words on my computer screen saying to myself is this for real, or a fictional story. I kept reading and I discovered this is real! Very well written, and congrats on being selected as an apprentice for November.

      • Dreamhowl profile image

        Jessica Marello 5 years ago from United States

        @Lori: Thank you! A lot of people don't realize the care that goes into owning rats, especially introducing a rat that is from a different litter. I appreciate the comment! And rats have fantastic personalities.

      • By Lori profile image

        By Lori 5 years ago from USA

        Nice article. It should be a lot of help to anyone wanting a pet rat. Taking care of a pet rat is as important as any other pet so what a good hub ! My daughter had a rat and she liked it's intelligence and personality.