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Pet Rats/biting rat.


QUESTION: I have four rats. The first two I got from pets at home, they are brothers. My third rat, rodney, was a rescue rat. He's very timid but he doesn't bite, and I introduced him to my other two rats and they instantly bonded. My fourth rat. Named bitey. He bit me twice causing a lot of blood and bruising on my finger. He's aggressive towards my dominant rat Rudy. When I introduced him to Rudy first, in a neutral territory, he got on his back and "humped" him. Rats are suppose to ignore each other when they first meet, and bitey didn't ignore rudy, but Rudy ignored bitey. I then got all four rats in the neutral territory, (and I had my mum nearby if a fight broke out) bitey went for Rodney,the timid one, and bit him and rodney sqealed and it was all very traumatic for him.

I let my rat Rudy run around my room, and he sniffed bitey through the cage bars of bitey's cage and bitey stuck his nose out and tried to aggressively bite Rudy.

My question is why is this rat so aggressive towards people, and my other rats?

My rats are the most friendliest rats, and didn't have ANY bother with Rodney when I first brought him home. I bet all my money that they would take in bitey if he wasn't aggressive! I'm not giving bitey away as people may not have as much patients as I do, and to be honest, even though he bit me twice, I feel very sorry for him. I don't know his past.
Thanks for your time. :)

ANSWER: Hi Emma,
It is not true that "Rats are suppose to ignore each other when they first meet," it is normal for them to be aggressive with each other.

There are 3 main reasons why rats bite people: the mistake a finger for food, they are afraid, or they have abnormally high testosterone levels that make them aggressive. What was the exact situations the times Bitey has bitten you?

And, BTW, I don't think it's a good idea to name a rat Bitey, even though he bites. Don't you want him to stop biting?

---------- FOLLOW-UP ----------

QUESTION: Hi, he actually follows my hands around the cage to actually try and attempt to bite me. I put thick gloves on and he sits and chomps on them trying his best to get through to them. His body language isn't scared or nervous,

The first time he bit me was when I was dropping a handful of oats in his bowl while he was at the other side of the cage, and he hopped over and chomped on my thumb and hung on.

Also, while I was at the pet shop, the girl who worked there said that his brother was vicious and bit people, so she took him, thinking that bitey would have a better chance of getting a new home. She said that bitey didn't bite, and that he was friendly but timid. I dont know whether she was lying or not, but she didnt choose to to actually pick him up to put him in the box, but to corner him with the box until he went in, which me a little unsure.

I heard that if rats aren't breed right, they can be born aggressive, which would explain why both him and his brother are both aggressive.

Or maybe even a brain tumour?

Thanks for getting back to me as quick as you did. :)

That is definitely too much testosterone. Rats aren't born aggressive, but it can be a genetic tendancy, and they can develop abnormal aggression when their hormones kick in at maturity. The only way to stop it is to have them neutered. I doubt it is a brain tumor. They are very rare. It sounds like genetic aggression.

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Debbie Ducommun


I can answer any questions about pet rats, but you will probably be able find answers to simple questions more quickly on my website at If you have a life-threatening emergency you can try calling me at 530-899-0605. I am not usually on the computer on the weekend.


I have been "The Rat Lady" since 1985 and am recognized as one of the world's experts on pet rats. I have 3 published books and already answer lots of questions about rats daily.

President of Rat Assistance & Teaching Society

I am a monthly columnist for Pet Business magazine, and my writing has appeared in other magazines. I have 3 published books.

BA in Animal Behavior

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