I totally agree with the others. If you're going to have cats & dogs together, it's best to have the cats first, as they will have established their domain & will certainly let the dog know who's boss! I've had cats & dogs together for over 20 years and they've all got on fine. I would send a word of caution, though, about getting a border collie with cats - it's in a collie's nature to round up everything that moves and that includes cats!! I have 5 cats and 2 dogs, a GSD bitch and a male border collie (he was supposed to be a sheepdog, but he's useless!). The collie, even though he's now nearly 5 yrs old, still tries to round up the cats. One of them just beats him up when he tries it, two totally ignore him (he gets soooo upset!!), one jumps up as high as she can get and the other poor old lass absolutely hates him and is completely paranoid! Her best friend is the GSD, who is gentle and loves her!