Aggression in rats





One of the most common questions I get asked is whether or not rats bite.
My answer is 'if it has teeth, it can bite'. This goes for any animal, even humans. Any creature that owns teeth can and will bite if the situation is right (or wrong, as the case may be).

However, generally, rats are gentle creatures who bite far less than other small furry rodent pets.
Often, people with no rat experience will group rats together with mice, hamsters, gerbils, or degus and assume they're all the same in temperament and behaviour.
This is not really accurate, and rats are quite unique amongst small furries.

Rats can bite, but generally, they don't like to, and will not do so without a reason. And a lot of the time, they will give you fair warning beforehand (this is where knowing your rat body language comes in helpful).

Unlike syrian hamsters, rats are a social species, who naturally live in large groups with a complex social structure.
When your survival depends on being accepted by your group (of which the human owner is part), it isn't a good idea to go around biting whenever you are simply in a bad mood. A rat who did so would quickly be reprimanded or even ousted from the social group eventually.
And for a wild rat, having no group could mean death.
Thusly, rats are very tolerant and will put up with a lot before they resort to biting. Once they have bonded, rats tend to view their owner as a more dominant member of the group, so they really have to feel that there is no other option before they bite someone.
They will usually try all other options before resorting to that. It simply isn't in their best interests to be aggressive when so much of their survival depends on getting along with others.

Rats are also very intelligent, far moreso than other small, rodent pets. This gives them the ability to work a situation out in their mind and make an informed decision on how to respond, unlike some less intelligent animals who will simply bite on instinct if they feel threatened.

Rats have also been selectively bred over the years to be docile and accepting. Laboratory rats have to be tolerant, otherwise they would never put up with the tortures they have to endure. Rats as a species are generally patient, tolerant and sweet-natured.

But this does not mean a rat will never bite, just that there is less chance of them doing so than other pets. If a rat does bite, there is always a reason for it, and most of the time it is due to human error, in that we either didn't recognise their warnings, or we ignored them. Rats don't bite 'just because', there will be a reason for it, even if we aren't initially sure what it is.
The most common reasons for a rat to bite a person are:

Fear
Rats that have not been handled properly, or at all, or have been abused in the past, may bite through desperation because they are so scared.
If they associate being handled by a human with pain, unpleasantness or stress, they are going to do whatever they can to avoid having to be in that situation again, just as we would.
However, even when it comes to fear, most rats don't like to have to bite people unless there is no other option. A scared rat would much rather flee than fight. It simply isn't in their nature to attack unless they are cornered and fear for their life.
As a point of interest, wild rats are exactly the same and would much rather run away from humans than attack them. As a small, vulnerable prey animal, it is much more sensible to avoid conflict from the start, if at all possible. Wild rats will only bite humans if cornered or attacked, otherwise they would much rather run away from you. Turning and attacking you wastes time and energy they could be using on making an escape.
In my experience, pet rats that are scared enough to actually bite a human in a serious way are almost always rats that have been abused in some way.

Rats that have simply never been handled in their life and are under-socialised may struggle, or squeak, or panic when they are picked up, but they will not often bite. A rat that has never been handled has also never been handled badly, so they tend to just be squirmy and difficult to hold rather than aggressive.
But a rat that has been handled cruelly or roughly is more likely to bite, because it strongly associates humans with unpleasantness.
Rats will put up with a lot before they resort to biting, particularly once they are bonded to a person, so if a rat is so scared it feels it needs to attack all the time, it has very likely had past abuse rather than just not enough handling.
This can be overcome with gentle contact and teaching the rat that humans are no longer going to hurt him. Scared rats tend to come around pretty quickly when handled by knowlegeable, gentle, calm people. See this page for advice on handling rats.

You can tell a nervous rat as they tend to hide away and run from your hand. A nervous rat will not approach you and bite you. He will run and hide from you, and only bite if he is pursued and feels trapped or cornered, i.e, he has no other choice.

Pain
Rats may bite when they are in pain, particularly if it is a sudden, unexpected pain, like a foot or tail trapped in a cage door. These are almost always instant, reflex reactions where the rat will bite at anything to try and escape the pain. If your hand happens to be nearby, the rat won't stop to think about it.
Rats are naturally hide their pain well, so if you have a normally friendly rat who has suddenly begun to bite or nip, it is worth considering a vet visit to ensure they are not unwell or sore, even if they appear to be ok.

Learned behaviours
Some rats that have been poorly handled for a while, or been allowed to get away with bad behaviour, will bite because they have learned that it gets them what they want.
For example, if a rat comes to a new home for the first time and is grabbed at by an eager child, then nips that child through fear, it will usually be dropped, or put back in it's cage. The rat will therefore quickly learn that if it nips, it gets left alone and doesn't have to put up with being handled.
So it is then no longer handled because the owners are scared, which just exacerbates the problem and a vicious circle is formed. In the end, it may bite not because it is necessarily scared anymore, but because it has learned that this is the way to get what it wants. Rats are extremely intelligent, and they learn quickly.
Rats like this need confident handlers who will show them that their previous biting will no longer work, and that they are going to be handled, whether they like it or not. Rats will quickly learn that the biting is no longer effective, and stop doing it. Rats, like all animals, do what works. If something no longer brings the outcome they want, they will stop doing it.

Hormones/territoriality
Some rats, particularly bucks, can have a surge of hormones in their first year which can sometimes make them quite demonstrative. I would say that hormonal aggression is the most common type of aggression I hear about.
Rats have a strict social heirarchy, and as their owner, you are at the top of this heirarchy. You are the alpha, if you like.
The rats will have their own structure amongst themselves also, and their own rat alpha, but you are the ultimate rat, and you are the alpha over everyone else.
Rats naturally adore their alphas, so once it is established that you are the boss, they should be accepting of most things you wish to do to them (this being the reason rats are so tolerant and accepting of their owners.)
However, some rats have a hard time accepting that they are not the alpha themselves. These rats often make life as difficult for the other rats in the group as they do for you. To them, you are simply another rat to be dominated, and they will treat you accordingly.
A dominant rat does not have to be told what to do if he doesn't want to, so if you try to dictate what he is allowed to do, he will see no problem with putting you in your place, just as he would with another rat.

And remember, while you may not think you are trying to show dominance over your rats, you do so without even realising it.
Everytime you pick up a rat, you are dominating it, as you're dictating where it is going to go, and when, and how. You are in control of what they get fed, and when. You are in control of when they are allowed to come out for their run, and in control of what behaviours they are allowed to demonstrate once out of the cage. We have the last word on every aspect of our pet's lives, and this is what the alpha rat does.
Dominance in rats can be very subtle and we, as owners, demonstrate it daily in the way we treat our rats, even if we don't realise it.

It is not acceptable for a rat to bite a person through dominance, and it is a problem that needs to be sorted out, otherwise you will never have a good relationship with that rat; he sees you as below him, and will treat you as such, rather than seeing you as his protector and someone he can trust.

A hormonally aggressive rat can be recognised by the fact that they tend not to be fearful. Some rats like this will actually approach the human and even persue them or chase them. If a rat is actively going after you and trying to attack you, its likely a hormonal problem, not a fear issue. The general rule is that scared rats hide from you, hormonal rats pursue you.

Some time ago in the rat world, there was a trend of people pinning dominant/hormonal rats onto their backs and holding them there to 'teach them who is boss'. This was presumably an attempt to recreate how rats pin one another during dominance scuffles. You may still see this advice given today. However, the method has been largely abandoned by the rat community and few people believe in any more. At best, it makes no difference, at worst, you will get bitten. Like with alpha rolling in dogs, it is based on flawed interpretations of animal behaviour, and pinning and already stressed and hyped up animal into a vulnerable position is just asking to be chomped.

In cases of hormonal boys, castration is the usual first step, and often sorts the problem out on its own. These kind of issues are caused primarily by hormones, so removing them will greatly ease, or cure, the problem. Every rat I have ever had neutered for this kind of behaviour has improved as a result.

Sometimes there is a mixture of hormonal problems and learned behaviours going on, particularly if the rat has been behaving like this for a long period of time. So while castration will sort out the hormones, it can't do anything about a rat's behaviour patterns and what it has learned to do. Behavour modification will be needed alongside the castrate, in these situations.
Some rats are what is termed as 'cage aggressive', meaning they are fine when out of the cage, but aggressive if you try to touch them inside it. In my experience, does can often be this way inclined more than bucks.
While this isn't as big a problem as an all round aggressive rat, it is still not ideal for most average pet owners.
But in my opinion, we ask a lot of our rats, behaviourally speaking. We expect them to be almost perfect, and sometimes we forget our responsibility to respect them and their space in the process.
I do not thrust my hand into my rats igloo to yank him out while he's sleeping. I could, and most of my rats wouldn't care. But I consider it to be disrespectful to the animal, and when I hear people say they were nipped for this kind of action, I always think 'well, what did you expect?!'
Remember, this is a prey species; in the wild, they are food to a lot of other animals, and a lot of things are out to kill them, so they have to be alert. If your rat is sleeping, and the next thing he knows he is being grabbed and yanked out into the open, it is hardly surprising that he may react with sudden fear or surprise, and might even nip. Imagine how you would feel if you were fast asleep in your bed and someone suddenly grips you and tries to yank you out! You'd probably react with a touch of alarm or defensiveness, too.
Before you handle your rat, think about what he's doing, what his body language is like, what he's communicating to you. If people took more notice of their rat's mood and mindset before plunging their hand in to whip them out for a cuddle, there would be less bites.

In the same vein, remember that female rats who are pregnant or nursing a litter can be more aggressive than they would usually be. They are protecting their babies, just as any mother would, and hormones also play a part in this. While not all girls with babies have a character change, and many are happy for their owner to handle their babies, it is definitely worth remembering that mother rats have the potential to be nippier than usual.

Redirected Aggression
This is what you see when a well meaning owner sticks her hand inbetween two fighting rats to break them up, and ends up on the receiving end of a nasty bite or scratch. Many rat owners have obtained bites this way, including myself.
Redirected aggression is, as the name suggests, when a rat's aggression toward another rat ends up being mistakenly directed at the owner when they try to intervene. Dogs and cats can also show redirected aggression.
It is not personal. The rat doesn't hate you, he was simply very wound up, probably quite stressed and confused, and when he felt or saw your hand coming toward him, he lashed out at it as though it were the other rat he was fighting with.
And he almost certainly didn't even realise it was your hand; it was just another object close to him for him to vent on. Some rats also redirect aggression onto objects. I've seen a fair few rats who, during power play with other rats, have begun to aggressively attack and bite/chew a toy or igloo. It is just like a person who is enraged and wants to punch someone, but punches the wall instead.
The best thing to do is simply to not try to handle rats that are very frustrated or amped up. If your rat has just had a fight with a cage mate, and is still stomping about, fur bristled, really on edge, don't touch him! Let him calm down a bit first. Or if you must handle him, do so extremely cautiously.
While it might be very instinctual for us to leap in and break up a rat fight when we see our babies hurting each other, try not to. This is one of the main causes of rat owners being bitten. Almost every rat owner I know has been bitten trying to break up a fight, or through redirected aggression. If you must break up two fighting rats, either do so by wrapping a thick towel round your hands to protect them, or try a water spray with a firm, hard jet on it (I keep a water spray to hand in any situation where I think rats will fight). Again, this kind of thing really doesn't mean your rat hates you, or has a poor temperament, it simply means he was wound up, stressed out, on edge, and he lashed out at an innocent bystander! Rats do this to other rats, too. I've seen a few instances where two boys have been fighting, with a third watching on, and one of the boys will then turn and have a go at the watching rat, who wasn't bothering either of them.

Biting through the bars
It is a good idea not to feed rats through the bars of the cage, however quick and convinient this may be. This teaches the rat that anything which pokes through the bars is food, so they will lunge at the bars to grab whatever it is, and they don't stop to check whether it is a finger or a piece of food!
These bites are accidents; the rat isn't attacking you, its biting what it thinks is food.
Most rats recoil and stop immediately once they realise it isn't food after all, but obviously they can still have given you a nasty bite by then. Lots of rats are given titbits through the bars and will have this 'lunging at the bars' problem as a result. If this bothers you, do not feed them other than by your own hand through the door, or in their dish. It doesn't take long at all for a rat fed through the bars to learn this behaviour, so its better not to feed through the bars from day one.

neurological/genetic issues
Some rats can show aggression as the result of a neurological problem, like a brain tumour. Some humans with brain tumours can also become irrationally aggressive 'for no reason'. I've heard of a few rats in the past who had such issues, and ended up even biting on themselves or anything in their surroundings in their rage and confusion. If a rat does have this problem, it is kinder to have him put to sleep; he won't get any better, and will be living a miserable life. Thankfully, this kind of thing is quite rare. I have never personally had a rat with this issue myself, but I know friends who have.
Some rats also just have really crap genes, to put it bluntly. Temperament can be inherited, so if mum and dad were both temperamental, aggressive rats, chances are some of the offspring will be, too. Good breeders don't breed from rats who show aggressive tendencies, but unfortunately not all rats on this earth are bred with such care and consideration.

aggression with other rats
This is called 'rat aggression' as opposed to 'people aggression', and the two are not necessarily related. Lots of rats who despise their own kind and try to attack them are wonderfully sweet and trustworthy with humans.
And similarly, many rats who are aggressive to humans are perfectly amiable with their own kind. The two behaviours are not linked, just as with dogs. When you hear of a dog attacking another dog, someone inevitably says 'a child could be next!' but this is rubbish; one behaviour does not equal the other. Animals are able to tell the difference between their own kind, and humans.

But rat on rat aggression is more common than rat on human aggression, for the simple reasons that rats are territorial animals who live in social groups with a hierarchy, and this hierarchy is complex and constantly changing. We also have our domestic rats living in somewhat unnatural situations where they are expected to accept new rats they have never met, or are not related to, and live harmoniously in a restricted area (ie, a cage) in groups of usually just one gender. In the wild, rats live in large groups, but they are often family groups, with rats all being related in some way, growing up in that group, and the group being comprised of mixed sexes and ages.
Rats from outside the group would be viewed as intruders, and chased off.

So given the quite 'unnatural' situation we keep our domestic rats in, its amazing they are as accepting as they are of each other. When a bite is not a bite
I've had a lot of rats come into my sanctuary over time with the attached warning that they are aggressive and will bite.
I've even had some which were due to be euthanised because they were apparently such severe biters. But in all cases, these rats have arrived here timid, but in no way aggressive, and none of them have ever bitten me.
This lead me to wonder where people were getting the idea that the rat was aggressive, when I saw no signs of it.
There are possibly several reasons for this, but I think the main one is that people don't understand the difference between a rat who will bite through the bars because it mistakes a finger for food, or a rat who is play nipping, and genuine, serious rat aggression.

If you are ever bitten seriously by a rat who means business, you will know about it; there will be blood everywhere, and in really bad bites you may even need stitches. Rats have serious teeth on them that can easily bite down to the bone, and rat bites are very painful.
But rats do use their teeth in other ways, which people often seem to misconstrue as aggression.
Baby rats, for example, may nip and tug at your skin when they're playing. They will do this to other rats too, and it is in no way meant as an aggressive act, and does not hurt. Puppies also do this when young, and it is simply excitement and trying to initiate play.
However, some people view any rat which puts its teeth anywhere near skin to be aggressive, and misunderstand the rat's intentions. This is quite sad, since being included in a baby rat's playtime is a wonderful thing.
Some rats also groom their owners with their teeth, nibbling along their skin and licking them. This is a bonding activity, as you are a member of their group. This kind of thing feels a little like being scratched lightly along the skin, and again, does not hurt. But I wonder how many people experience this for the first time and think the rat is trying to bite or savage them?
And lets not forget the main reason a rat would be reported to be aggressive with its past owner, but not once placed in a knowledgable home: incorrect handling.
Please read this page for info on how to properly handle rats.

Suffice to say, the average rat that is handled gently, calmly, and with respect has no reason to bite anyone.

In summary, rats are not aggressive animals. They are extremely tolerant, gentle, forgiving and trusting. Nature has shaped them to be this way so as to thrive in a large social group. The gentle nature of the rat is what makes it a superior pet to a hamster or rabbit for a child.
But do not forget, rats must be respected and not expected to put up with being mishandled, scared, stressed or abused. Supervise all children, all the time, when handling rats and always try to remember that fear and pain are the two main causes of rat bites.
If you raise a rat that is well socialised, not scared, and not in pain, you have little reason to ever worry about a bite.
I trust rats more than I trust any other species of animal I've owned. In my 16 years of owning rats, I have been bitten maybe 5 times, all of which were my own fault, and most of which occured in the early days before I learned how to properly 'read' rats.

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