Like many of the other infertiles I know, our first babies were our furbabies. We have 2 little dogs with very different personalities.
One is Dakota - a very laid back dog who loves to be loved on but can also just hang out on the couch or in a patch of sunlight and be very content. You could do anything to Dakota and he would never even consider snapping at you. I actually (accidentally, don't call PETA on me) cut his ear one day while trying to cut a knot out of the hair on his ear. He yelped but never even came close to snapping at me.
The other one is Murfy. Granted, Murfy is younger. However, he has always been more of an attention hog. He loves to be the center of attention and gets jealous if someone else gets attention. Case in point? If I sat next to Derek and kissed him on the cheek, Murfy would be on the back of the couch trying to get between us so that he could get kissed instead. In addition, if he wants to be petted, he will put his body under your feet so that you will rub him. Murfy isn't as tolerant of behavior that he didn't request though. If you try to get something out of his mouth that he wants, he won't hesitate to take your hand off. And, if he is asleep on your side of the bed and you go to move him so that you (the boss) can get into the bed, he will growl at you.
Both of our dogs have been very gentle around other people's children, but we have never brought our own baby home before. I had no worries about how Dakota would react. But Murfy? Well, I was afraid we would have to take him to the pound.
In preparation for bringing a baby home, we pulled out one of my old Cabbage Patch Kids, freshened up the baby scent, wrapped it in a receiving blanket and carried it around. When we had the "baby", we would talk to it and rock it and kiss on it. If Murfy attempted to get on the "baby", we would divert his attention with other toys or with treats. We played the sound of a crying baby on the computer while we attempted to calm the "baby". And once Carder was born, we took a receiving blanket to wrap him in, got it good and scented up like him, and then let them smell it.
To our delight, both dogs have adapted well to having Carder here at home. There have been no issues. So far, we have had some sniffing and some curious looks into the crib/pack and play by Murfy, but no aggression. Even more surprisingly, he spends hours on the floor in the nursery - almost as if he is guarding the baby.
I am not sure if our actions made this a smooth transition or if it would have been fine either way. But, just in case you are bringing home a new baby to an existing jealous furbaby, I thought I would let you know what worked for us.