Cats and Dogs as Pets

Hi I am Melissa and I am new to this site. I hava very agressive cat that is not good around other cats and I really want a dog in fact a Beagle. Does anyone have any suggestions. The cat is an indoor cat and is nearly 10 years old. I am interested to hear all kinds of feedback, thank you.

Do you know anyone that has a dog that you could introduce to your cat to see if he/she will take to it? It would be best if you could do a trial run before adopting (or buying) a pup and then having to rehome it.