• Hissing: A sign of distress sometimes heard during a confrontation. A rat hissing at you is likely to bite if handled without great care.
• Squeaking/Shrieking: Most rat squeaks are pitched higher than the human ear can hear. A short squeak is a mild protest, whereas a longer one is a more serious complaint. A shriek like sound indicates pain.
• Grinding teeth: This is known as bruxing. Rats grind their teeth to keep them at the right length. However they also do this when content, in the same way cats purr. Just to confuse things they also do it at times of stress! Hopefully you will be able to tell what's motivating your rat at that point in time if he/she is doing this.
• Arching back and vibrating ears: Female rats do this to indicate that they are in heat. It's intended to attract male attention, but can be directed at human owners as well.



• Chasing, sidling, boxing, rolling on their backs: These related behaviours can be seen when rats square up for a confrontation. If they are sufficient for one rat to win the encounter then nothing more serious will occur. However if neither rat backs down then a full on fight with biting and possible injuries will start.
• Grooming: Rats groom each other to reinforce bonds and status. Sometimes the grooming is between friends. Sometimes it's a way for dominant rats to enforce their status either by forcing grooming on a subordinate or by demanding it. Unwilling recipients of grooming may squeak in protest.
• Head swaying: A technique used by red eyed rats who have poor eyesight to increase their depth perception.
• Erect fur: An angry or stressed rat who wants to appear bigger than he is. Don't put your hand near a rat in this mood unless you don't mind being bitten.

Agression towards humans

A rat biting humans is probably doing so because it's scared. Two important ways to avoid unexpected bites are don't take a rat by surprise, for example by grabbing it while it's sleeping, and don't try and break up a rat confrontation by hand. A rat in a fight is likely to confuse an intruding hand for an opponent. If you have a rat which is clearly frightened of humans, you need to build up its trust. Start by sitting near the cage (with a good book) and leaving the door open. In due course the rat's curiosity, perhaps helped by learning from its cage mates, will lead it out of the cage over to explore you. Having food available to reward the rat with will probably help. When the rat is used to being on and with you, try stoking it and eventually picking it up. Try and treat the rat with the care and gentleness you would a scared child.

If a rat only bites in its cage it's probably being territorial and sees you as an intruder. You can try to win it over by making it associate your hand with treats and a bite as resulting in no treat. If it sees its cagemates getting something nice while it misses out, it will soon start to get the idea that biting is a bad thing. Some otherwise non biting female rats start to bite in the later stages of pregnancy or when their kittens are very young. After their babies are weaned they will stop.

A few rats do appear to be genetic biters and will never learn to stop. The best thing to do with these is make sure that they are not allowed to breed.