Our menagerie is currently one dog, two cats and five fish. We also regularly look after another dog for friends and, amazingly, everyone gets on just fine, even though they have all come to us at different times.

We have had two cats for some time and generally it was one older one and one younger one on a rotating basis. Then we had one cat that lived to 21 and an unfortunate run with the younger ones where one was stolen and the next one had cancer - so we suddenly found ourselves with no cats! We took the opportunity to go for two the same age so they could play more together and one week prior to Christmas about 7 or 8 years ago came a little brother and sister act that are called Spike and Min!

At that stage we had an older dog called Ben who was a retriever cross and the biggest, soppiest, loyalest blonde you could hope for. He was a fierce guardian of the home but incredibly gentle and curious about these furry missiles that kept hurtling around under his nose and legs... And the cats just seemed quite fearless about him!

The relationship that quickly developed was that Min (the girl) would curl up and sleep with him, usually hidden somewhere in his bushy tail and Spike would make Ben the first point of contact whenever he walked into the house - and the tales he used to tell him! Spike has always been a chatty cat so he loved having Ben to talk to. He also used to rely on Ben keeping other cats out of the garden as Spike is not really as brave as he makes out.

When Ben died poor Spike had a tough time managing his territory on his own and he really missed Ben a lot. Min exchanged the warm dog body for her sleeping arrangements and discovered how easy it was to burrow under a pillow on the bed!

Eighteen months later I was ready for another dog and we acquired Jasper (who gets a lot of mentions in my Hub Pages). Jasper is a very energetic Kelpie/Staffie cross and burst into the quiet cat world with his never ending enthusiasm for life and amazing dog smile!

At first the cats did not react well but we made sure they got lots of attention and had plenty of places they could hide from this new lunatic! Gradually they got braver and it was Min, of course, who first took a stand. She seemed to understand that Jasper was a working dog and his instinct is to round everyone up - so she just let herself be rounded up into a corner then quietly scooted though his legs to freedom again! The fact that Jasper had no idea what to do once he had rounded something up probably helped a bit....

Spike took longer to accept him but, as I have said, he is not so brave. But now, with Jasper at 5 and the cats at 8 they all live together very happily. Min still stirs the dog up and Spike now tells all his tall stories to Jasper (and then Jasper tells me)!

Where do the fish come into this, well, we have them in a pond in the garden and they are all called Eric so we don't get confused! And so far, the cats have not worked out that what swims in the pond from which they often drink is in any way related to what appears in their dishes at night.......

So my very long answer to your question is "just do it" but make sure everyone has a safe place and reward good behaviour consistently. Cats will hide until they have checked out the situation and then they will, as always, assert their superiority. There may be the odd scratched nose but that is part of the learning process.

And make sure you have your camera to hand when those first meetings take place they will be funny and memorable.