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Pet Rats/Rat dominance


So I had two rats, a siamese, Sal, and an albino, Mooney.  I adopted them from my local shelter, and when I got them, they got along famously.  After a month or so however, they started fight, Sal being hugely aggressive.  We neutered Sal, and that was fixed, if you'll pardon the pun.
     So, now they live in a huge cage, and we saw this lonely adult male rat at the Humane Society, and we got him.  The cage is two large levels, so we cut them off, resident rats on top, new rat on bottom.  Every day or so, we put a little water in the bathtub, rub vanilla extract on their fur, and put them in for fifteen-twenty minute sessions.  They were getting along so well, I put them in the new rat's part of the cage, monitoring carefully.  The problem is, I cant distinguish serious fighting from healthy dominance, so I have no idea when to step in!  Sal has, after finishing grooming himself, puffed up, arched his back, and sidled up to the new rat, sometimes mounting, or pinning.  Often, this turns into boxing or a nose-off, with teeth displays.  Than, the new rat will run off, and Sal will follow, the whole time, the new rat is letting out short, loud squeaks.  
         The new rat now has several bites on his sides and back, and Sal has a slash on his cheek.  I honestly don't know what to make of it.  Some books/sites say that nipping is normal, other say no blood.  Some say not puffing/arching, while others say it's fine.  I need serious help.  I just want a straight answer from someone who knows what their talking about.  

I appreciate your help,

Hi Ella,
These rats are lucky to have been adopted by you!  The way to tell serious aggression from dominance is the puffed fur. If one of the rats puffs his fur, he is out for blood, and you need to immediately remove the other rat. You don't really want to pick up a rat whose fur is puffed up because he could bite you.

You can try correcting the rat who puffs his fur up by talking to him very sternly, telling him, "NO!" "Knock it off, you be a good boy." "You need to be gentle." If he doesn't immediately put his fur down, then you need to remove the other rat and try again later. They should not be together unsupervised until there is absolutely no more fur puffing.

You'll find instructions for introducing rats on my website at

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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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