From Stand Off to Rat Pile – Introducing rats successfully
Rat introductions are one of the biggest stressors in our rats lives, along with losing cage mates, major hierarchy disputes and major illness. They represent a significant hurdle that rats have to overcome. Unfortunately if we want our rats to be happy living life with friends this is also an unavoidable occurrence. Anything we can do to lower the amount of stress the rats are under and make the transition as smooth as possible is well worth it. Rats are creatures of routine, in the wild they form complex family’s with well-established hierarchy’s, a rat living outside the hierarchy or excluded by it will often just give up (there has been lots of reports of perfectly healthy rats seemingly dying of loneliness when excluded from a group). Thankfully in our pet rats this isn’t usually fatal, however it is true that the groups are much happier and healthier when everything remains stable. Even when used to change, whether it be in their hierarchy or environment, this can still be very difficult for some rats. Understand what happens in an introduction is a very useful part of making sure you pick the best introduction method for you and your rats.
In any introduction there are several things that need to happen in order for them to be successful, in fact these fit very well with how human teams form so we use the same terms here;
• Forming - The rats need to familiarise themselves with each other’s smells, this is the rat form of getting to know each other as a lot of info is carried in both urine and from the rats general odour. With a simple sniff a rat can find out; how dominant another rat is, if they are fit and well, what kind of foods they are eating, where they have been and so on. In this phase there is a lot of sniffing both of any urine trails found and the rats themselves. Sometimes rats will lick up tiny droplets of pee to get an even better reading. At first it is relatively low stress and rats are very curious but it quickly moves into the next step.
• Storming – This is the rats establish the groups hierarchy, this is very important to rats as their place in the hierarchy defines who they are, what perks they get and how they act around each other. Think of this as them trying to establish what rules they live by, learning who not to cross, who they can be cheeky with, and who to turn to when they’re having a bad day. Unfortunately as the stage name implies this often includes fights or stand offs and rats attempting to force others to submit or establish who is the strongest. This is also the highest stress step and one that needs to be kept as short and injury free as possible. Introduction methods either focus on lowering the daily stress in this step (but generally making it go on for longer) or speeding this step up at a high stress level in order to reduce the total amount of stress the rats undergo in the long term.
• Norming – This is where the group begins to function, generally very few scuffles break out but there is a certain amount of tension, no one wants to get it wrong but occasionally things don’t quite work and leads to a reminder of the rules (hence the scuffles). You will normally notice that the group often sleeps together but generally more in its former sub groups (so new rats together and old rats together or all together rather than mixed piles). It’s very much about the rats getting used to the new situation and beginning to fall into the new status quo. They also learn each other’s body language and pick up the ‘dialect’ that the group ‘speak’. This is why often related rats do settle together quicker, they have been brought up to behave in the same way and already smell similar. Norming is less stressful than Storming, but all rats (even then existing group rats) will be at elevated stress levels still.
• Performing – This is where the group finally become a proper family, the whole cage will begin to work better, rats will have extra confidence and move freely between one sleeping pile to the next. You will often notice specific friendships formed which can be across the former groups but the group as a whole will be happy. This state normally continues until some other issue causes the hierarchy to be disrupted (illness, someone getting too big for their boots, losing a cage mate etc.).
In any introduction there are several things that need to happen in order for them to be successful, in fact these fit very well with how human teams form so we use the same terms here;
• Forming - The rats need to familiarise themselves with each other’s smells, this is the rat form of getting to know each other as a lot of info is carried in both urine and from the rats general odour. With a simple sniff a rat can find out; how dominant another rat is, if they are fit and well, what kind of foods they are eating, where they have been and so on. In this phase there is a lot of sniffing both of any urine trails found and the rats themselves. Sometimes rats will lick up tiny droplets of pee to get an even better reading. At first it is relatively low stress and rats are very curious but it quickly moves into the next step.
• Storming – This is the rats establish the groups hierarchy, this is very important to rats as their place in the hierarchy defines who they are, what perks they get and how they act around each other. Think of this as them trying to establish what rules they live by, learning who not to cross, who they can be cheeky with, and who to turn to when they’re having a bad day. Unfortunately as the stage name implies this often includes fights or stand offs and rats attempting to force others to submit or establish who is the strongest. This is also the highest stress step and one that needs to be kept as short and injury free as possible. Introduction methods either focus on lowering the daily stress in this step (but generally making it go on for longer) or speeding this step up at a high stress level in order to reduce the total amount of stress the rats undergo in the long term.
• Norming – This is where the group begins to function, generally very few scuffles break out but there is a certain amount of tension, no one wants to get it wrong but occasionally things don’t quite work and leads to a reminder of the rules (hence the scuffles). You will normally notice that the group often sleeps together but generally more in its former sub groups (so new rats together and old rats together or all together rather than mixed piles). It’s very much about the rats getting used to the new situation and beginning to fall into the new status quo. They also learn each other’s body language and pick up the ‘dialect’ that the group ‘speak’. This is why often related rats do settle together quicker, they have been brought up to behave in the same way and already smell similar. Norming is less stressful than Storming, but all rats (even then existing group rats) will be at elevated stress levels still.
• Performing – This is where the group finally become a proper family, the whole cage will begin to work better, rats will have extra confidence and move freely between one sleeping pile to the next. You will often notice specific friendships formed which can be across the former groups but the group as a whole will be happy. This state normally continues until some other issue causes the hierarchy to be disrupted (illness, someone getting too big for their boots, losing a cage mate etc.).
Considerations when picking what to do
In order to minimise the stress on the rats involved you can minimise the length of the process, or reduce the amount of stress the rats go through in any one time. Which works best depends a lot on the rats involved, things such as their age, sex, hormone levels, history, self-confidence, individual characters, health and existing group size and dynamics can completely change the approach the fits best. Here are some of the things that you should think about before deciding which method suits you best;
Age
This matters particularly in bucks, a buck kitten under the age of around 13-14 weeks smells different, roughly the age where their fur starts to roughen, thicken and feel more ‘buckish’ their smell changes too (this is a sign that testosterone is beginning to take a role in their development), this is discernible to the human nose (they smell sweet as kittens and more earthy as ‘bucks’) so is blindingly obvious to a rats more sensitive nose. Before this change adults bucks will generally not see the babies as a threat or challenge to their position and focus more on making sure the babies know there position at the bottom of the pack. The babies will also generally submit more readily which in turn will make the adults more relaxed. Sometimes does will react in a similar way, or attempt to mother the new babies, but this is often a lot harder to predict, unless you have a particularly maternal girl. Baby to baby intros (where both groups are under 12-14 weeks) are even easier still, with kittens generally accepting each other as best friends within minutes. One thing to be very careful with though is very young/small babies. Introductions can often become rough, and whilst an adult rat would cope with it very well a real youngster is more delicate and they can get injured. With the very young this chance goes up. A good rule of thumb is to never introduce rats under 7-8 weeks, however rats grow and mature at different rates. A kitten should be nice and solid feeling and be a reasonable size (be careful about introducing bucks much under 200g and does much under 175g). This will give them the physical strength and resistance to cope well with the situation.
Older rats, particularly bucks, who are slowing down and showing their age often begin to lose interest in cage politics or displays of dominance. In bucks this is linked to a drop in testosterone (you may notice some or all of their fur losing some of its buckish coarseness) as well as the general slowing down and settling that most old rats go through. This generally makes introductions easier, however you do need to take into account increasing frailty or risk of injury, and the fact older rats may become stressed more easily.
Sex
Bucks and does often react in quite different ways to introduction situations. A lot is down to their differing priorities. In bucks where dominance and hierarchy position is key to passing on their genes, establishing themselves securely in the hierarchy is very important (which often makes understanding their behaviour much simpler). In does who do not have the same drivers (hierarchy is still there but more a means to the ratty perks in life as opposed to having a major impact on procreation) personalities take on a more significant role. This generally means that bucks will need to establish their dominance to some degree in most introductions and they will do this in a fairly consistent manner in most cases. Does will often be smoother, however they can be more unpredictable as it is more down to the individual taking a like or dislike rather than sorting out who’s boss. This difference can mean that you can be a bit more flexible with Doe introductions, and sometimes it’s necessary to take a different approach, with bucks it is generally better to focus on sorting out the hierarchy quickly
Hormone levels
Hormonal periods effect does and bucks differently. In bucks hormones are at their highest around 6-12 months (though sometimes rats younger and older will get affected), these generally manifest as slowly increasing bolshiness, during this time there fur might get particularly greasy and they may start displaying over the top dominance behaviours that verge on the aggressive towards other rats and or humans (though most bucks get through this teenage phase with only a little bit of grumpiness). As they age bucks hormones levels usually settle then begin to drop into old age, however changes in the group hierarchy (such as the loss of a strong alpha or an illness in the cage) can lead to an artificial hormone surge (a strong alpha can suppress other rats hormone levels) later in life. During hormonal phases bucks become especially bothered about being the highest up the ladder they can and making sure everyone knows it and so introductions can be more challenging. In a settled group where rats are going through a hormonal phase but are not actively causing difficulties then this shouldn’t prevent introductions, however if the group is unsettled by hierarchy challenges it is generally not a good idea to introduce until things have settled down.
In does the hormone levels are quite different, girls hormones will rise and fall over a roughly 4-5 day cycle in line with their heats from around 6 weeks (typical age of first heat). Knowing when your girl or girls are on heat can be massively useful in introductions, especially when they are not going smoothly. Having a girl on heat in the group changes the group dynamic significantly, it creates a very good distraction as everyone is focused on her mad behaviour. If you have a particularly awkward girl try beginning intros when she is on heat (you can judge this from her displaying – ears vibrating, arched back, when touched on the back or rump). Introducing girls to new girls will also often artificially trigger a heat in some or all the girls so don’t be surprised if your cage goes a little mad for a while. The other hormone level issue that can effect doe introductions is when a doe suffers from a condition causing her hormones to go out of control. Unlike bucks, does generally don’t have natural hormone surges longer than their heat (unless pregnant) and so if you have a doe that is becoming increasingly aggressive it is worth getting her spayed before introducing other rats to her as she may well have polycystic ovaries or another ovarian issue. Other than these issues it is worth bearing in mind that both pregnant does and bucks that have recently been mated can be particularly fired up in terms of hormones, so where possible minimising introductions at these times is worthwhile.
History
A rat who has never lived with other rats, or has spent a significant period of time on their own (especially when young) will struggle a lot more with introductions than one who is familiar with other rats. This is all about knowing how to interact with other rats, rats speak a complex language made up of body language as well as behaviours, smells and sounds outside our hearing. There are natural variations (or dialects) to this in different groups of rats but the main themes are the same. A rat who has grown up not knowing these, or one that has spent sufficient time on its own not using them, can find it very difficult to read the signals other rats are giving off and vice versa. If the option is available it can work a lot better to introduce them to one or two very understanding patient rats to begin to learn to be rats again before introducing them to a larger group. Observing their behaviour around these rats should give you an idea if there will be problems. Another element of rats history that can have quite an impact is territorial behaviour. This can be caused by poor treatment in earlier life or learned behaviour (reinforced by whatever was the issue being removed on sign of aggression). A rat who is obviously aggressively cage territorial is not one that you should put in a confined space with other rats without a long and gradual build up or really knowing the rats involved, so in this case small space intros can be a bad idea. In most cases it is worth attempting to resolve or reduce territorial behaviour before introductions start. Looking into neutering (more often successful in bucks than does) and/or lots of time spent training the behaviour away can help reduce this. It is worth considering though that some territorial rats feel more secure in smaller spaces (less space to dominate and control) so if you are confident the rat will not injure other rats it may be worth trying a smaller space intro.
Self Confidence
A rat who lacks self-confidence is often the one that will cause most problems in any introductions. They will feel the need to go beyond normal levels to prove that they are superior in any dispute. This being the case having a good feel for any rats who are like this in a group can be very useful. It can be a good idea to introduce a good number of confident rats (including the alpha where he/she is confident) first before introducing these. This will often result in the confident rats intervening if bullying happens (as opposed to more normal hierarchy disputes) and can settle things down much quicker. Introducing new rats that lack self-confidence but are also wanting to be dominant can be difficult too, this can often cause long drawn out stalemates, where the new rat won’t back down but also won’t push to be dominant (typically involving lots of squeaking and standing on hind legs pushing people away). This is generally where it can be a good idea to up the unfamiliarity factor (to break the stalemate a little) by going for a walk or drive with them in a carrier (unfamiliar smells and movements quickly distract them from the stalemate).
Individual characters
This is one of the things that makes rats such brilliant pets, it’s also one of those things that can make introductions a walk in the park or a nightmare. Doe introductions are particularly dependant on this as their likes and dislikes are often more complex. Learning your rats and how they interact with each other normally will give you a better feel for what may and may not work for them, but don’t be surprised if they react differently to what you expect for their first introduction, it is very different to their norm after all. Once you have experienced your first introduction with each rat you should have a good idea of how they will respond in the future and things that can help or make it worse.
Health
Introducing unwell or weak rats is always a real concern, with introductions comes stress and stress has a dramatic impact on our rats ability’s to fight infection and illnesses. It is something that needs to be taken into account and keeping stress levels to a minimum should be your primary concern. If the rats have a mild chronic condition that responds to stress it can be worth covering them with medication during introductions and getting them over as quickly as possible. It is also worth taking into account how physically capable the unwell rats are as well as who they are being introduced to. If they are being introduced to boisterous young rats and are very weak, putting them in a confined space together may well be too much. Introducing two old infirm rats should be much more straightforward regardless of method. It is also worth bearing in mind that long drawn out intros can be more stressful to the individual than short quick ones. You need to balance how poorly the rat is, how much stress they may take and whether it is better in a short sharp dose or in smaller more separate ones. In extreme cases where the rat is very ill you may need to make the decision not to introduce them, or select their future cage mate/s very carefully.
Existing group size and dynamics
Whilst it may seem harder to introduce rats into a large group, with all those different personalities and ego’s, it can actually be easier. This is in part due to the new rats being somewhat overawed by all the new faces and strength of the existing group and so submitting quickly. It can also be down to the large group being more familiar with the coming and going of new rats thus lowering overall stress levels a bit. However in the case of rats that have been on their own for a significant time this can actually make situations worse and it can be worth introducing them to a small group first (personality dependant). Group dynamics also makes a big impact, a settled group will absorb new members quickly, an unsettled group will often cause issues and increases the chance of injury’s occurring. The rats in the group are already highly stressed so adding in more will elevate them to even higher stress level. Stressed rats, much like stressed humans, will react in more extreme manners to the same stimulus, this will mean that accidents and truly aggressive fights are more likely to occur. Better to wait until your group is settled before introducing new rats.
Age
This matters particularly in bucks, a buck kitten under the age of around 13-14 weeks smells different, roughly the age where their fur starts to roughen, thicken and feel more ‘buckish’ their smell changes too (this is a sign that testosterone is beginning to take a role in their development), this is discernible to the human nose (they smell sweet as kittens and more earthy as ‘bucks’) so is blindingly obvious to a rats more sensitive nose. Before this change adults bucks will generally not see the babies as a threat or challenge to their position and focus more on making sure the babies know there position at the bottom of the pack. The babies will also generally submit more readily which in turn will make the adults more relaxed. Sometimes does will react in a similar way, or attempt to mother the new babies, but this is often a lot harder to predict, unless you have a particularly maternal girl. Baby to baby intros (where both groups are under 12-14 weeks) are even easier still, with kittens generally accepting each other as best friends within minutes. One thing to be very careful with though is very young/small babies. Introductions can often become rough, and whilst an adult rat would cope with it very well a real youngster is more delicate and they can get injured. With the very young this chance goes up. A good rule of thumb is to never introduce rats under 7-8 weeks, however rats grow and mature at different rates. A kitten should be nice and solid feeling and be a reasonable size (be careful about introducing bucks much under 200g and does much under 175g). This will give them the physical strength and resistance to cope well with the situation.
Older rats, particularly bucks, who are slowing down and showing their age often begin to lose interest in cage politics or displays of dominance. In bucks this is linked to a drop in testosterone (you may notice some or all of their fur losing some of its buckish coarseness) as well as the general slowing down and settling that most old rats go through. This generally makes introductions easier, however you do need to take into account increasing frailty or risk of injury, and the fact older rats may become stressed more easily.
Sex
Bucks and does often react in quite different ways to introduction situations. A lot is down to their differing priorities. In bucks where dominance and hierarchy position is key to passing on their genes, establishing themselves securely in the hierarchy is very important (which often makes understanding their behaviour much simpler). In does who do not have the same drivers (hierarchy is still there but more a means to the ratty perks in life as opposed to having a major impact on procreation) personalities take on a more significant role. This generally means that bucks will need to establish their dominance to some degree in most introductions and they will do this in a fairly consistent manner in most cases. Does will often be smoother, however they can be more unpredictable as it is more down to the individual taking a like or dislike rather than sorting out who’s boss. This difference can mean that you can be a bit more flexible with Doe introductions, and sometimes it’s necessary to take a different approach, with bucks it is generally better to focus on sorting out the hierarchy quickly
Hormone levels
Hormonal periods effect does and bucks differently. In bucks hormones are at their highest around 6-12 months (though sometimes rats younger and older will get affected), these generally manifest as slowly increasing bolshiness, during this time there fur might get particularly greasy and they may start displaying over the top dominance behaviours that verge on the aggressive towards other rats and or humans (though most bucks get through this teenage phase with only a little bit of grumpiness). As they age bucks hormones levels usually settle then begin to drop into old age, however changes in the group hierarchy (such as the loss of a strong alpha or an illness in the cage) can lead to an artificial hormone surge (a strong alpha can suppress other rats hormone levels) later in life. During hormonal phases bucks become especially bothered about being the highest up the ladder they can and making sure everyone knows it and so introductions can be more challenging. In a settled group where rats are going through a hormonal phase but are not actively causing difficulties then this shouldn’t prevent introductions, however if the group is unsettled by hierarchy challenges it is generally not a good idea to introduce until things have settled down.
In does the hormone levels are quite different, girls hormones will rise and fall over a roughly 4-5 day cycle in line with their heats from around 6 weeks (typical age of first heat). Knowing when your girl or girls are on heat can be massively useful in introductions, especially when they are not going smoothly. Having a girl on heat in the group changes the group dynamic significantly, it creates a very good distraction as everyone is focused on her mad behaviour. If you have a particularly awkward girl try beginning intros when she is on heat (you can judge this from her displaying – ears vibrating, arched back, when touched on the back or rump). Introducing girls to new girls will also often artificially trigger a heat in some or all the girls so don’t be surprised if your cage goes a little mad for a while. The other hormone level issue that can effect doe introductions is when a doe suffers from a condition causing her hormones to go out of control. Unlike bucks, does generally don’t have natural hormone surges longer than their heat (unless pregnant) and so if you have a doe that is becoming increasingly aggressive it is worth getting her spayed before introducing other rats to her as she may well have polycystic ovaries or another ovarian issue. Other than these issues it is worth bearing in mind that both pregnant does and bucks that have recently been mated can be particularly fired up in terms of hormones, so where possible minimising introductions at these times is worthwhile.
History
A rat who has never lived with other rats, or has spent a significant period of time on their own (especially when young) will struggle a lot more with introductions than one who is familiar with other rats. This is all about knowing how to interact with other rats, rats speak a complex language made up of body language as well as behaviours, smells and sounds outside our hearing. There are natural variations (or dialects) to this in different groups of rats but the main themes are the same. A rat who has grown up not knowing these, or one that has spent sufficient time on its own not using them, can find it very difficult to read the signals other rats are giving off and vice versa. If the option is available it can work a lot better to introduce them to one or two very understanding patient rats to begin to learn to be rats again before introducing them to a larger group. Observing their behaviour around these rats should give you an idea if there will be problems. Another element of rats history that can have quite an impact is territorial behaviour. This can be caused by poor treatment in earlier life or learned behaviour (reinforced by whatever was the issue being removed on sign of aggression). A rat who is obviously aggressively cage territorial is not one that you should put in a confined space with other rats without a long and gradual build up or really knowing the rats involved, so in this case small space intros can be a bad idea. In most cases it is worth attempting to resolve or reduce territorial behaviour before introductions start. Looking into neutering (more often successful in bucks than does) and/or lots of time spent training the behaviour away can help reduce this. It is worth considering though that some territorial rats feel more secure in smaller spaces (less space to dominate and control) so if you are confident the rat will not injure other rats it may be worth trying a smaller space intro.
Self Confidence
A rat who lacks self-confidence is often the one that will cause most problems in any introductions. They will feel the need to go beyond normal levels to prove that they are superior in any dispute. This being the case having a good feel for any rats who are like this in a group can be very useful. It can be a good idea to introduce a good number of confident rats (including the alpha where he/she is confident) first before introducing these. This will often result in the confident rats intervening if bullying happens (as opposed to more normal hierarchy disputes) and can settle things down much quicker. Introducing new rats that lack self-confidence but are also wanting to be dominant can be difficult too, this can often cause long drawn out stalemates, where the new rat won’t back down but also won’t push to be dominant (typically involving lots of squeaking and standing on hind legs pushing people away). This is generally where it can be a good idea to up the unfamiliarity factor (to break the stalemate a little) by going for a walk or drive with them in a carrier (unfamiliar smells and movements quickly distract them from the stalemate).
Individual characters
This is one of the things that makes rats such brilliant pets, it’s also one of those things that can make introductions a walk in the park or a nightmare. Doe introductions are particularly dependant on this as their likes and dislikes are often more complex. Learning your rats and how they interact with each other normally will give you a better feel for what may and may not work for them, but don’t be surprised if they react differently to what you expect for their first introduction, it is very different to their norm after all. Once you have experienced your first introduction with each rat you should have a good idea of how they will respond in the future and things that can help or make it worse.
Health
Introducing unwell or weak rats is always a real concern, with introductions comes stress and stress has a dramatic impact on our rats ability’s to fight infection and illnesses. It is something that needs to be taken into account and keeping stress levels to a minimum should be your primary concern. If the rats have a mild chronic condition that responds to stress it can be worth covering them with medication during introductions and getting them over as quickly as possible. It is also worth taking into account how physically capable the unwell rats are as well as who they are being introduced to. If they are being introduced to boisterous young rats and are very weak, putting them in a confined space together may well be too much. Introducing two old infirm rats should be much more straightforward regardless of method. It is also worth bearing in mind that long drawn out intros can be more stressful to the individual than short quick ones. You need to balance how poorly the rat is, how much stress they may take and whether it is better in a short sharp dose or in smaller more separate ones. In extreme cases where the rat is very ill you may need to make the decision not to introduce them, or select their future cage mate/s very carefully.
Existing group size and dynamics
Whilst it may seem harder to introduce rats into a large group, with all those different personalities and ego’s, it can actually be easier. This is in part due to the new rats being somewhat overawed by all the new faces and strength of the existing group and so submitting quickly. It can also be down to the large group being more familiar with the coming and going of new rats thus lowering overall stress levels a bit. However in the case of rats that have been on their own for a significant time this can actually make situations worse and it can be worth introducing them to a small group first (personality dependant). Group dynamics also makes a big impact, a settled group will absorb new members quickly, an unsettled group will often cause issues and increases the chance of injury’s occurring. The rats in the group are already highly stressed so adding in more will elevate them to even higher stress level. Stressed rats, much like stressed humans, will react in more extreme manners to the same stimulus, this will mean that accidents and truly aggressive fights are more likely to occur. Better to wait until your group is settled before introducing new rats.
The Main Different Methods
1, The Carrier or Small Space method (broad use) - This starts off with introductions in a small neutral space or moves directly to an empty small space such as a cat carrier or small cage until the group is settled. Cage size and furniture is increased in stages once the rats seem settled and relaxed at each step, until the rats are happy in a large space. Once introduced unless blood is drawn the rats are not separated again. This method works well in the vast majority of cases
2, The Neutral Space method (moderate use) - Rats are introduced in a neutral space. In most cases low level scuffles are allowed but any large fights that may cause injury are interrupted or separated. After a length or time the rats are separated and return to their own cage. This is repeated a number of times until the rats seem disinterested in each other or become friends, they are then moved into a fully cleaned out cage and the above is repeated or if it goes well they move in permanently.
3, The Heavy Supervision method (moderate use) - This method uses a moderate neutral space to start bonding, the owner then supervises and intervenes with even minor aggression or roughness but otherwise handles them as normal with lots of interaction. Once rats have been out for most of the day and have slept and interacted in a relaxed manner then moving on to a carrier style introduction works well, or straight into a larger neutral cage.
4, The Cage Swap method (limited use) - This is normally an earlier step before going into the neutral space method of intros. It starts off with both rats/groups placed in cages next to each other but not close enough that they could bite each other through the bars. Once they become accustomed to each other’s smell the rats are then swapped into each other’s cage and spend some time in it. This may be followed by swapping back again for a period or moving on to the neutral space method.
2, The Neutral Space method (moderate use) - Rats are introduced in a neutral space. In most cases low level scuffles are allowed but any large fights that may cause injury are interrupted or separated. After a length or time the rats are separated and return to their own cage. This is repeated a number of times until the rats seem disinterested in each other or become friends, they are then moved into a fully cleaned out cage and the above is repeated or if it goes well they move in permanently.
3, The Heavy Supervision method (moderate use) - This method uses a moderate neutral space to start bonding, the owner then supervises and intervenes with even minor aggression or roughness but otherwise handles them as normal with lots of interaction. Once rats have been out for most of the day and have slept and interacted in a relaxed manner then moving on to a carrier style introduction works well, or straight into a larger neutral cage.
4, The Cage Swap method (limited use) - This is normally an earlier step before going into the neutral space method of intros. It starts off with both rats/groups placed in cages next to each other but not close enough that they could bite each other through the bars. Once they become accustomed to each other’s smell the rats are then swapped into each other’s cage and spend some time in it. This may be followed by swapping back again for a period or moving on to the neutral space method.