Your dog has a very high prey drive. You are fortunate that she is okay with your other dog, because a dog with a high prey drive that is not good with other dogs can be a real nightmare.
There are a few things you can do to make her more manageable. The first is to stop playing any game that makes her interested in prey. A flirt pole (a ball on the end of a fishing pole type stick), tug of war, and sometimes even catch can make this problem worse.
The other thing that high prey drive dogs need is an activity. Teachig her obedience is very important. She should respond immediately to sit, down, stay and other basic commands. Use the time that you play with her now to work on her obedience.
Sometimes almost nothing works. Dogs with high prey drive (like greyhounds and Afghan hounds) are sometimes impossible to have around other animals. Cats are usually in danger if they run, which most of them will.