I just would like to tell you that rats are very intelligent animals and that they react very well with other pets in your house. This is my dog Luke and my rat, Tar, and this is Lucy. Tar, Luke, and Lucy have grown up together since they were little. Tar is about eighteen months old and Lucy is about ten months old, and Luke here, he is my old boy, he is about ten years old. He has no problem interacting with the rat, they can crawl all over him and kiss him and take food right out of his mouth and he does not have a problem.
Now I highly recommend not leaving your rats unsupervised with any of your pets in the house because you never know when accidents happen, in which the rat can get trapped somewhere or the rats can chew on electrical wire. But normally rats, if they grow up with other pets in the house, like Luke, they have no fear of him. He has never hurt them or upset them and they can groom him, cuddle up next to him, and play with him, and there is usually never any problem. I had Luke around them since they were teeny tiny little babies, they use to sleep on him, and he never has had a problem with them.
Rats also enjoy being in colonies together, so it is good to have more than one rat together, so two rats or more are much happier and well adjusted than one rat, unless you have other pets that they can play with. I would like to show how my rats interact with my cat. I would also like to show you how my little kitty reacts with the rats. She has also grown up with them and usually does not have any problem with them. So I got her when she was a teeny tiny kitty out of the dumpster, and the rats socialize with her and never have a problem, they don’t bite and she has never hurt them. But then she tolerates having them groom her and licking her. They chase each other around the house. Whoops, she has had enough of the rats. I highly do not recommend leaving them unsupervised but as friends while you are supervising rats and playing with them, they should have no problem together, playing with your other pets in the house.