Dogz 4 how to get a dog pregnant

Well, first you need to wait until they're adults.
You can check by going their separate profiles and look for Adult.

Now, what you do is use love potions and keep all other toys and distractions out of the picture. They need to focus on themselves. Go ahead, play some soft and slow music from the music thingy. Throw out some love hearts too, but don't leave the box out. They'll start playing with and want you to play too. Now, if first time the charm isn't it, keep trying. They WILL fall in love eventually. Once that happens the female dog is sure to be pregnant. Can't give you details on how long or when the puppy will show up (haven't played in a while). After that check the female dog's profile and it should say 'pregnant: yes'.

Good luck :)