Why Is My Rat Biting Me All Of A Sudden? What To Lookout For

Rats are, generally speaking, very friendly and caring pets. So, it can come as a nasty surprise when a rat that you’ve got a great relationship suddenly lashes out and starts biting you. If your pet rat starts biting you it can be a bit worrying, so why does this happen, let’s find out?

Pet rats can start biting you out of the blue if they feel threatened, startled, sick, or in a strange and scary environment. It’s worth noting rats are typically friendly pets if cared for correctly so biting isn’t normally a problem your should encounter. If your rat bites you, it’s typically something you have done or not picked up on their situation.

Often, however, there are warning signs that a once peaceable rat is becoming a little bit less friendly and they tend to relate to the rat’s health. So, let’s examine what the warning signs are, what you should do when your rat bites you and how to stop it from happening again.

Why Do Rats Bite?

We’ve explored the reasons that rats bite in this article Do Pet Rats Bite? so, as a brief recap – rats tend to be driven to bite for two reasons: biological and behavioral.

That is, they either bite because something is going wrong with their biology or because they’ve learned something that isn’t right. Assuming that your rat hasn’t bitten you previously – it’s unlikely that you’ve somehow recently trained your rat to bite you.

So, in the case of a rat biting you out of the blue that means the most likely explanation for this is a biological one or its environment has changed.

What Are The Warning Signs Of Biological Problems In Rats?

The good news is that you will often get warning signs that your rat isn’t well or has an injury and usually for a prolonged period before they bite. So, you need to learn to recognize these as a rat owner because fast intervention (or recognition of an issue) can ensure you never get bitten by your pets.

The warning signs are:

  • Your rat is sleeping all the time when it used to play or climb around in the cage.
  • Your rat has stopped wanting to leave the cage and shows no interest in the outside world.
  • Your rat is rejecting cuddles or strokes and shying away from people in general.
  • Your rat has either stopped eating or has massively reduced their food intake.
  • Your rat has started to lose weight.
  • Your rat is squealing, whining or making other sounds that might indicate some form of distress.
  • Your rat is fighting with its cage mates at the slightest excuse.
  • Your rat has a swollen belly (this is, usually, a sign of pregnancy).
  • You rat has lost their coordination/motor skills and appears drunk (this is, often, a sign of an ear infection or possibly, a tumor)
  • One side of its body is weaker than the other.
  • Check your rats teeth are healthy, problems with their mouth will prevent them from eating.

What Do You Do If Your Rat Becomes Aggressive?

If your rat bites, you then you need to wash the wound out, sterilize it with some anti-bacterial agent and then, if necessary, cover it until it stops bleeding.

Then, it’s time to deal with the rat and you want to ensure that you’re not going to get bitten again, so some decent gloves and a long-sleeved shirt are in order.

If The Rat Is Sick Or Injured

It’s time for a visit to the vet. We’re going to assume that you’d have treated any problem that you could recognize by now, so it means that it’s time for a trip to a professional. In our experience, sick/injured rats that lash out are usually very sick or injured – they are naturally friendly and don’t want to hurt you when they’re in their right minds.

If The Rat Is Pregnant

When a rat is pregnant, she becomes, quite naturally, super protective of her unborn kittens and, of course, the kittens following the birth too. If you think she may be pregnant, it’s best to remove her from the cage and place her in a separate cage. Clean this cage every other day until the kittens arrive.

Don’t clean the cage for a week after this – if she’s aggressive toward you during this period, it’s because she doesn’t really understand what’s going on. If you do interfere with her litter in the first week, there’s a chance that she might abandon it.

She should start to calm down between 7 and 14 days, and by the end of 28 days she will be back to her good old, good tempered self.

If The Rat Is Reaching Maturity

Male rats are known to become more aggressive as they reach sexual maturity and there’s one very simple way to avoid this problem – have them neutered before it arises.

Unless you intend to breed rats there is no good reason to keep a sexually mature male in an un-neutered state around – they are prone to pee all over the place and fight a lot, you don’t need that, and nor do the other rats that it shares space with.

You can neuter a male after sexual maturity, but it’s not guaranteed to have the calming effect that pre-maturity neutering has.

I have recently written an article all about rats exerting their dominance to establish their position in the hierarchy and how they also like to play fight, you can read the article here Why Are My Pet Rats Fighting?

If The Rat Is New To Your Home

Rats do not like new places. If they find themselves in a new house or with new rats around them – they can find it very threatening. This triggers a biological safety drive and while it doesn’t always result in displays of aggression – it can do.

Sometimes, you need to give them time to adapt. If they’re being aggressive with each other, you may need to remove the most aggressive rat for a period of time and then try to gradually re-introduce them to the rest of the group.

If The Rat Has Learned To Bite

This is a rarity, but it can happen. If the rat doesn’t want to be picked up and it bites, and you put it down then it learns that biting is a good way to avoid being picked up. This is, of course, not what you want. So, the way to deal with this is to disabuse your rat of the notion that this strategy works.

Get some gloves and when it nips at you, pick it up and pet it for 10 minutes. Try to ensure that you cover the gloves in your scent before this for maximum effect (that means rub them against your body – don’t spray them in perfume).

After 3-4 days, the rat should stop trying to bite and, in most cases, they will also start to enjoy this kind of treatment. Rats do enjoy being handled by their owners most of the time, after all.

In short, you’ve helped them unlearn their behavior.

Rats That Have Been Abused

If you’re fostering a rescue rat, then this may take a lot of time and care to build a bond of trust with the animal. Gloves, love and regular handling are going to go a long way towards making this happen and many rats will eventually return to normal under this kind of regime. However, some rats will simply never fully recover from the trauma of abuse.

You Have Startled Your Rat and Its Bit If Fear

Another reason your rat could bite you (slight nip) is if you have given him a fright. Rats are prey animal after all and they are always on the look our for predators. If you catch them unexpected or if they have poor eyesight they might nip in self defence giving you a small warning shot.

I have been caught out with this only once in all the years I have owned rats and it’s fair to say that it was definitely my fault giving him a bit of fright.


Why is my rat biting me all of a sudden? The odds are very good that your rat is not very well or has some sort of physical condition that is causing them to lash out. That means you’re going to need to treat whatever it is that is causing your rat distress. You may need to talk to your vet in order to get the best treatment for you rat and it’s important that you do so in short order if you can’t diagnose and treat the problem yourself, quickly.

The good news is that, in the main, rats don’t bite their owners and you shouldn’t see a temporary lapse in behavior as a long-term threat to the ends of your fingers. Rats are sociable and friendly creatures that genuinely show affection for the people that own them, give your little pal a few days to get back to their old selves and you’ll both be back on speaking terms in no time.

Darren Black

I'm Darren Black, the owner, and author of AnimalKnowhow.com. I am from Scotland, United Kingdom and passionate about sharing useful information and tips about properly caring for an animal's wellbeing.

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