I started out with one 17 1/2 yrs ago. But she seemed to be so lonely when I was at work that I got a second one to keep her company and I'm so glad I did. They were the best of friends. I lost the 16 yr old in March and I can tell a difference in how the other one is acting now but of course she is 17 1/2 yrs old. If you go to my album there is a pic of them sleeping together in their bed. My vote is to get two.