Confession, I had to laugh at that too.

I have 2 cats and 2 sugar gliders (small furry critters with big eyes that run and jump and glide in tree branches and whose #1 enemy in the wild would be a snake!). While I would never take the snakes out while my suggies were out playing, I have no worries whatsoever of my boa harming them or my cats.
Many captive snakes tend to kind of imprint on a particular prey item and it can take a bit of work to switch them to something different when they don't recognize it as food. Use common sense and your kitties should be fine!
Not all boas are super big. Is yours for sure a female? If so, she will get a bit larger, but if it's a male, you're probably looking at more like 6-7-ish feet or so. Also, if you keep your boa on rats for it's lifetime, it probably won't get quite as big as it might if you put her on rabbits. Rabbits tend to spark a major growth spurt and they will really start to pack on the size if they eat rabbits.
And lastly, boas are NOT ball pythons. Many boas seem to truely enjoy handling. I handled mine from day one and she ate for me no trouble on the 3rd day we had her. Just be gentle and sensitive to her stress level and maybe keep it to only a few minutes at a time til her first meal with you, then handle away!
